Malaria epidemiology and interventions in Ethiopia from 2001 to 2016

Assessing insecticide susceptibility status of Anopheles mosquitoes in Gondar zuria district, Northwest Ethiopia

Insecticide-based vector control, which comprises the use of insecticide-treated bed nets (ITNs) and indoor residual spraying (IRS), is the key method of malaria control in Ethiopia. However, its effectiveness is threatened as malaria vectors become resistant to insecticides. Thus, the aim of this study was to monitor the insecticide susceptibility status of malaria vectors. WHO susceptibility tests were used to detect knock-down and mortality rate in the wild malaria vectors collected in Gondar zuria woreda, Northwest Ethiopia. The WHO diagnostic doses of 0.75% permethrin, 0.05% deltamethrin, 0.05% alpha-cypermethrin, 0.1% propoxur and 0.25% pirimiphos-methyl were used. The major malaria vectors in Ethiopia, Anopheles gambiae s.l Anopheles funestus group, and Anopheles Pharoensis, were susceptible, to pirimiphos-methyl and propoxur. However, resistant to permethrin (mortality rate of 88.8%), alphacypermethrin (mortality rate of 67.5%), and deltamethrin (mortality rate of 73.8%). Although permethrin restoration was only 96% in permethrin resistant Anopheles mosquitoes, the efficacy of alphacypermethrin and deltamethrin was totally restored by pre-exposure to PBO. The susceptibility of malaria vectors to pirimiphos-methyl, propoxur, and PBO + pyrethroid insecticides is encouraging for successful malaria control. Further investigations are needed to better understand the molecular basis of pyrethroids insecticide resistant-malaria vectors.

Anopheles mosquito fauna, blood meal sources and transmission intensity from high and moderate malaria endemic areas of Ethiopia

This study investigates malaria vector dynamics in Lare and Asendabo, southwestern Ethiopia, areas with limited entomological information. From July to December 2021, mosquitoes were collected from 56 randomly selected houses using Pyrethrum Spray Catches, CDC light traps, and Human Landing Catches. Blood meal sources (human, bovine, goat) and circumsporozoite proteins (CSP) were detected via Enzyme-linked immunosorbent assays (ELISA), and mosquitoes were analyzed for physiological state, and Plasmodium infection. The entomological inoculation rates (EIR) for Anopheles gambiae s.l. and An. funestus were calculated, and species identification was performed by PCR on CSP-positive and randomly selected samples. A total of 2,565 mosquitoes from four Anopheles species were collected, with An. gambiae s.l. dominating. Indoor collected anophelines (53%) surpassed outdoor (47%). PCR confirmed An. gambiae s.l. as An. arabiensis and An. funestus as An. funestus and An. leesoni. Twenty two An. funestus tested positive for Plasmodium while Plasmodium-positive pools also included, An. gambiae s.l. (15), An. coustani (2), and An. pharoensis (1). The P. falciparum EIR for An. gambiae s.l. in Asendabo was 1.39 bites/person/month, while An. funestus had the highest bite rate (10.52 bites/person/month). Mixed blood meals and zoophilic behaviour were common, underscoring the need for species-specific, spatio-temporal vector control strategies.

Assessment of malaria treatment interventions: a critical analysis of government initiatives and causes of treatment failure at Port Loko Government Hospital, Sierra Leone

BACKGROUND

Malaria remains a significant public health challenge, particularly in sub-Saharan Africa, where it accounts for high morbidity and mortality rates. Sierra Leone, including Port Loko District, continues to experience a high burden of malaria despite government interventions. This study evaluates the existing government interventions for malaria treatment at Port Loko Government Hospital, examining the socio-economic determinants contributing to malaria treatment failure.

METHODS

The study employed a cross-sectional study design with a quantitative approach, involving 150 health workers and 150 women of childbearing age. A purposive stratified random sampling technique was used to ensure diverse representation. Primary data were collected using structured questionnaires, while secondary data were extracted from the District Health Information System (DHIS) and hospital records. Data were analysed using SPSS version 28.0, applying descriptive statistics (frequencies, percentages, means and SD) and inferential analyses (Chi-square tests and binary logistic regression) to assess associations between socio-economic factors and treatment-seeking behaviours.

RESULTS

Findings revealed that 90% of health workers were aware of malaria interventions, but only 68% reported high adherence to treatment guidelines. Among women of childbearing age, 40% sought malaria treatment at drug stores or pharmacies due to financial constraints, and a significant association was observed between socio-economic status and healthcare-seeking behaviour (2 = 9.32, df = 4, p = 0.05). Despite the fact that 73.3% reported the use of long-lasting insecticidal nets (LLINs), malaria prevalence remained high, suggesting additional risk factors beyond bed net usage.

CONCLUSION

This study highlighted persistent challenges in malaria control, including inadequate healthcare access, non-adherence to treatment regimens, and socio-economic constraints. Policy recommendations include strengthening malaria treatment adherence programmes, improving healthcare accessibility, and enhancing community-based malaria prevention strategies.

Low ITN utilization among households in SWEPR Ethiopia: challenge for malaria elimination, a mixed design approach

INTRODUCTION

To prevent malaria starting from 2005 more than 2 billion insecticide-treated nets (ITNs) have been distributed globally. Even though Ethiopia has been doing nationwide ITN distribution starting from 2016 with 64% ITN coverage, there is a significant gap in its utilization in different settings. Therefore, this study aimed to assess the utilization of ITN and associated factors among households in SWEPRS, 2023.

METHODS

Community-based mixed study designs were applied in the present study. Firstly, the malaria area was selected purposively and the study participants were reached by using multi-stage stratified sampling techniques. Data was collected by using structured and pre-tested tools through an electronic data collection software, Kobo tool kit was analyzed by using STATA version 14. The multicollenearity between independent variables and model fitness were checked by using the variable inflation factor (VIF) and Hosmer Lemeshow model fitness test, respectively. A binary Logistic Regression model was fitted to identify the associated factors. In the multivariable analysis, an adjusted odds ratio (AOR) with a corresponding 95% confidence interval (CI) was used to measure the strength of the association and the statistically significant association was declared at a P-value less than 5%. Focus group discussion (FGD) and in-depth interviews (IDI) were employed for the qualitative study and analyzed using Quirkos. The findings of qualitative data were presented in thematic analysis.

RESULTS

In this study, a total of 1,552 households participated. In all households, the ownership of at least one mosquito net per household was found to be 89% (95%: CI: 87.62-90.72%) whereas the proper use of ITNs was found to be 20.38% (95%: CI: 18.25-22.50%) in the region. From the multivariable logistic regression analysis, the urban residents, NGO employees, having a corrugated iron sheet house type, having good knowledge toward malaria, having good knowledge toward ITNs, having a favorable attitude towards malaria and having a favorable attitude towards ITNs had higher odds of the proper utilization of ITNs as compared to their counterparts. In addition to these, misconceptions about ITNs, unfair distribution of ITNs, lack of health education from health extention workers (HEWs), community resistance, improper use (use for other purposes) of ITNs and shortage of HEWs were explored barriers to ITNs use from the qualitative data.

CONCLUSIONS

This study showed relatively a high coverage of ITNS, but low proper ITN utilization among the households. Therefore, behavioral change communications (BCC) interventions and education and communication (IEC), interventions should be done in the region.

Spatial distribution of Plasmodium vivax Duffy Binding Protein copy number variation and Duffy genotype, and their association with parasitemia in Ethiopia

BACKGROUND

Duffy Binding Protein (PvDBP) binding to the Duffy antigen receptor for chemokine (DARC) is essential for Plasmodium vivax invasion of human reticulocytes. PvDBP copy number variation (CNV) might increase parasite invasion and thus parasitemia. We examined the spatial distribution of PvDBP CNVs and DARC genotypes and their association with parasitemia in P. vivax endemic settings in Ethiopia.

METHODOLOGY/PRINCIPAL FINDINGS

P. vivax isolates (n = 435) collected from five P. vivax endemic settings in Ethiopia were genotyped by amplifying the GATA1 transcription factor-binding site of the Duffy blood group and the CNV of PvDBP was quantified. Parasitemia was determined using 18S-based qPCR. The majority of participants were Duffy positive (96.8%, 421/435). Of the few Duffy negative individuals, most (n = 8) were detected from one site (Gondar). Multiple copies of PvDBP were detected in 83% (363/435) isolates with significant differences between sites (range 60%-94%). Both heterozygous (p = 0.005) and homozygous (p = 0.006) patients were more likely to have been infected by parasites with multiple PvDBP copies than Duffy negatives. Parasitemia was higher among the Duffy positives (median 17,218 parasites/µL; interquartile range [IQR] 2,895-104,489) than Duffy negatives (170; 78-24,132, p = 0.004) as well as in infections with 2 to 3 PvDBP copies (20,468; 3,649-110,632, p = 0.001) and more than 3 PvDBP copies (17,139; 2,831-95,946, p = 0.004) than single copy (5,673; 249-76,605).

CONCLUSIONS/SIGNIFICANCE

A high proportion of P. vivax infection was observed in Duffy positives in this study, yet few Duffy negatives were found infected with P. vivax. The significant prevalence of multi-copy PvDBP observed among Ethiopian P. vivax isolates explains the high prevalence and parasitemia observed in clinical cases. This suggests that vivax malaria is a public health concern in the country where the Duffy positive population predominates. Investigating the relative contribution to the maintenance of the infectious reservoir of infections with different genotyping backgrounds (both host and parasite) might be required.

An observational study evaluating the epidemiological and entomological impacts of piperonyl butoxide insecticide-treated nets (ITNs) compared to a combination of indoor residual spraying (IRS) plus standard pyrethroid-only ITNs in Amhara Region, Ethiopia, 2019-2023

INTRODUCTION

National malaria programmes must weigh the relative benefits of different vector control and elimination tools to prioritise resource allocation with the greatest impact. This study assesses the epidemiological and entomological impacts of piperonyl butoxide insecticide-treated nets (PBO ITN-only arm) compared with the combination of two annual non-pyrethroid indoor residual spraying (IRS) campaigns and standard pyrethroid ITNs (IRS+Standard Pyrethroid ITN arm) in the Amhara region of Ethiopia.

METHODS

An open-label, stratified block-cluster randomised trial was designed to compare the impacts of the two intervention arms. ITN distribution took place from June to July 2021. IRS campaigns took place from June to July 2021 and again in June 2022. Confirmed malaria cases reported during the high transmission season (September to December) were compared in the 2 years before (2019 and 2020) vs the 2 years after (2021 and 2022) the 2021 campaigns. The difference in An. gambiae s.l. vector density per trap and indoor resting density (IRD) was assessed between the two arms during the high transmission seasons 2 years after the 2021 campaigns.

RESULTS

Estimated malaria cases decreased significantly by 53.6% in the postintervention period compared with preintervention in the IRS+Standard Pyrethroid ITN arm (95% CI -72.9%, -29.8%) and by 55.9% in the PBO ITN arm (95% CI -73.0%, -32.5%), with no significant difference between these two arms (95% CI -30.9%, 24.0%). From the first to the second season postintervention, cases decreased non-significantly in the IRS+Standard Pyrethroid ITN arm (incidence rate ratio (IRR) 0.94; 95% CI 0.66, 1.47) but increased significantly in the PBO ITN arm (IRR 1.98; 95% CI 1.49, 2.67). Postintervention vector density and IRD were not found to be significantly different between intervention arms in either 2021 (vector density: IRR 0.78; 95% CI 0.47, 1.31; IRD: IRR 0.80; 95% CI 0.37, 1.75) or 2022 (vector density: IRR 1.27; 95% CI 0.75, 2.12; IRD: IRR 1.02; 95% CI 0.45, 2.28).

CONCLUSION

These findings suggest a positive impact of non-pyrethroid IRS deployed annually alongside standard pyrethroid ITNs in a setting of confirmed pyrethroid resistance. While an overall positive impact of PBO ITNs was detected, a waning impact of the nets 2 years postdistribution was observed.

Spatial, temporal, and spatiotemporal cluster detection of malaria incidence in Southwest Ethiopia

Background

Malaria is a major global health hazard, particularly in developing countries such as Ethiopia, where it contributes to high morbidity and mortality rates. According to reports from the South Omo Zone Health Bureau, despite various interventions such as insecticide-treated bed nets and indoor residual spraying, the incidence of malaria has increased in recent years. Therefore, this study aimed to assess the spatial, temporal, and spatiotemporal variation in malaria incidence in the South Omo Zone, Southwest Ethiopia.

Methods

A retrospective study was conducted using 4 years of malaria data from the South Omo Zone District Health Information Software (DHIS). The incidence rate of malaria per 1,000 people was calculated using Microsoft Excel software. Kulldorff SaTScan software with a discrete Poisson model was used to identify statistically significant spatial, temporal, and spatiotemporal malaria clusters. Graduated color maps depicting the incidence of malaria were generated using ArcGIS 10.7 software.

Results

Spatial clusters were identified in the districts of Dasenech (RR = 2.06, p < 0.0001), Hamer (RR = 1.90, p < 0.0001), Salamago (RR = 2.00, p < 0.0001), Bena Tsemay (RR = 1.71, p < 0.0001), Malie (RR = 1.50, p < 0.0001), Nyngatom (RR = 1.91, p < 0.0001) and North Ari (RR = 1.05, p < 0.0001) during the period from 08th July 2019 to 07th July 2023. A temporal cluster was identified as the risk period across all districts between 08th July 2022 and 07th July 2023 (RR = 1.59, p = 0.001). Spatiotemporal clusters were detected in Dasenech (RR = 2.26, p < 0.001) Salamago, (RR = 2.97, p < 0.001) Hamer (RR = 1.95, p < 0.001), Malie (RR = 2.03, p < 0.001), Bena Tsemay (RR = 1.80, p < 0.001), Nyngatom (RR = 2.65, p < 0.001), North Ari (RR = 1.50, p < 0.001), and Jinka town (RR = 1.19, p < 0.001).

Conclusion

Significant spatial, temporal, and spatiotemporal clusters in malaria incidence were identified in the South Omo Zone. To better understand the factors contributing to these high-risk areas, further research is needed to explore individual, household, geographical, and climatic factors. Targeted interventions based on these findings could help reduce malaria incidence and associated risks in the region.

Malaria burden and associated risk factors among malaria suspected patients attending health facilities in Kaffa zone, Southwest Ethiopia

BACKGROUND

Ethiopia has been progressing very well in controlling malaria in the past few years. However, shortly after the COVID-19 pandemic, an unpredictable malaria resurgence was observed in almost all malaria-endemic areas of the country, although the exact cause of which has not yet been identified. Therefore, this study aimed to investigate malaria burden and associated risk factors in one of the endemic zones of Ethiopia.

METHODS

A health facility-based retrospective and cross-sectional study design was conducted in the Kaffa zone, southwest of Ethiopia. Hence, a seven-year retrospective data on malaria positivity rate, interventional activities undertaken in the area, and climatic variables were collected from the patient's medical records, district health bureau, and meteorological institute, respectively. For the cross-sectional study, all malaria-suspected patients seeking medication at the health facilities in the Kaffa Zone administrative centre, Bonga town, during the study period (January-June 2024), were recruited in the study. Data on the patient's socio-demographic, socio-economic, behavioural, health facilities and environmental factors were collected using a structured face-to-face interview questionnaire. Data was analysed using Statistical Package for Social Science software (SPSS) (version 26) and the statistical tools used were descriptive statistics and logistic regression models. A significant level was considered at p < 0.05.

RESULTS

The study findings revealed a significant increment in malaria positivity trend (39.43%, n = 188,201/477,276, p < 0.0001) between July 2018 and June 2024. Also, the malaria positivity rate documented in the cross-sectional study was 50.72% (n = 315/621). Plasmodium falciparum was the dominant malaria parasite. The study identified weakened control measures (p = 0.006), limited awareness of the population (p < 001), and socio-demographic factors such as education (p = 0.037), age (p = 0.008), housing condition (p < 0.0001), low-income level (p < 001), and travel history to malaria-endemic areas (p = 0.001)] as risk factors associated with high malaria positivity rate. In addition, indoor residual spraying (IRS) and mean maximum temperature activity increased by 1 unit, and the malaria positivity rate decreased by 28 times (p < 0.0001) and 1.3 (p = 0.003), respectively. The months of July and September were strongly and positively associated with higher malaria positivity in the area (p < 0.05).

CONCLUSION

Even though Ethiopia was able to achieve a remarkable malaria burden reduction in the past few years, the recent interrupted malaria control activities, seasonal variability, and patient and health facility-associated factors have contributed to the current high malaria positivity rate documented in Kaffa zone, Southwest Ethiopia. This urges the need for immediate community sensitization activities to enhance the awareness of malaria, besides designing integrated vector control interventional strategies to tackle the current alarming situation in the zone.

Population travel increases the risk of Plasmodium falciparum infection in the highland population of Gardula Zone, South Ethiopia: A longitudinal study

Population movement influences malaria epidemiology and can be a threat to malaria control and elimination. In Ethiopia, highland dwellers often travel to lowland areas where malaria is endemic. The current study aimed to assess the incidence of malaria and risk factors among dwellers in two highland villages of the former Dirashe District (now Gardula Zone), South Ethiopia. A longitudinal study was conducted from 10/05/2018 to 30/11/2018. A total of 1672 individuals from 329 households were recruited via a systematic random sampling technique. Blood samples were collected from all consented family members. The study participants were interviewed via a pretested questionnaire. Bivariate and multivariate analyses were conducted to determine risk factors associated with malaria infection. A total of 4,884 blood samples were screened for malaria parasites in three rounds of surveys. Among those, 82 slides were positive for malaria parasites, 70 (85%) of which were collected during active case detection, and the remaining 12 (15%) were captured by passive case detection. Plasmodium falciparum accounted for 69.5% (57), and the remaining 30.5% (25) were Plasmodium vivax. The incidence of malaria in the highlands of Dirashe District was 0.2 infections per person-year at risk. Inhabitants who traveled to lowlands in the past 30 days (AOR = 2.60, 95% CI: 1.27-5.33) had a significantly greater risk of contracting Plasmodium falciparum infection. Those people traveling in May and November, those participants who had no formal education and agricultural workers, had a greater risk of developing malaria infection. Low bed net ownership (63.2%) and use (52.9%) have been documented among highland populations. This study revealed that people who travel from highlands to malaria-endemic lowland areas for agriculture are at increased risk of developing malaria. Hence, malaria interventions targeting travelers should be implemented to reduce the imported malaria burden in highlands.

Impact of nighttime human behavior on exposure to malaria vectors and effectiveness of using long-lasting insecticidal nets in the Ethiopian lowlands and highlands

BACKGROUND

Ethiopia continues to grapple with a persistent malaria burden, characterized by ongoing transmission and recurrent outbreaks. Human behavior influences both malaria exposure and the effectiveness of vector interventions, complicating malaria control efforts. Implementing tailored strategies that account for the complex interplay between human activities and vector behavior remains a challenge in both high- and low-transmission areas in Ethiopia, particularly for vulnerable highland populations and temporary labor migrants, due to lack of data. The aim of this study was to examine the spatiotemporal patterns of human-mosquito interactions and evaluate the effectiveness and suitability of long-lasting insecticidal nets (LLINs) in settings involving lowland resident populations, seasonal migrant workers and highland communities.

METHODS

Concurrent human and vector behavior data were collected from high-transmission lowlands (residents and temporary migrant workers) and vulnerable highlands populations. Hourly human behavior observations (HBOs), which examined LLIN use, indoor versus outdoor human presence and sleeping patterns, were paired in a crossover design with mosquito sampling using US Centers for Disease Control light traps (CDC LT) as a proxy for mosquito biting behavior. The study was conducted during the peak (October-December 2022) and minor (March-May 2023) malaria transmission seasons ('peak' and 'minor') for a total of 368 nights. In the highlands, four villages consisting of eight households per village were selected for surveillance; in the lowlands, four villages consisting of two resident villages and two farm sites with migrant workers, with eight households/structures per village or farm, were used for data collection. CDC LT and HBO data were integrated to evaluate HBO-adjusted human biting rates (HBO-adjusted HBR) of Anopheles mosquitoes.

RESULTS

In the highland villages, residents predominantly engaged in indoor activities, with their peak activity overlapping with the peak biting hours (1800-2200 hours). A substantial proportion of inhabitants slept indoors without LLINs in the peak and minor seasons (42.8% and 39.2%, respectively). Highland residents were significantly more exposed to malaria vectors indoors (88.4% peak, 88.6% minor) than outdoors during both transmission seasons. In lowland villages, both resident and seasonal migrant worker populations exhibited predominantly outdoor activity, particularly during peak biting hours (1800-2300 hours). Both residents and temporary migrants were significantly more exposed to Anopheles mosquitoes outdoors (resident: 65.0% peak, 67.1% minor; migrant: 70.5% peak, 80.0% minor) than indoors during both transmission seasons. LLIN usage was minimal and offered limited protection, with < 16.63% of person-time spent under nets by resident populations and 10.7% by migrant workers.

CONCLUSIONS

Malaria control in Ethiopia requires context-specific strategies tailored to diverse ecological settings that consider the impact of human behavior on exposure to Anopheles mosquitoes. Limited LLIN effectiveness, human activities coinciding with peak biting times and minimal LLIN usage create significant protection gaps. Comprehensive control necessitates supplemental tools addressing exposure in all locations and times. In the Ethiopian highlands, where indoor activities predominate, increased LLIN usage combined with targeted indoor residual spraying could reduce transmission. In lowland areas, both residents and seasonal migrant workers face relatively higher outdoor exposure risks, requiring additional measures, such as topical and spatial repellents. We recommend implementing data-driven, hyperlocal approaches based on specific human-vector interactions to enhance malaria control effectiveness across the Ethiopian highlands and lowlands.

Plasmodium falciparum and Schistosoma mansoni coinfections among the general population in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Due to the overlapping endemic regions and the high burden of both infections, coinfection with Plasmodium falciparum and Schistosoma mansoni poses distinct public health concerns that require coordinated, multifaceted interventions. There are epidemiological studies on the coinfection of these two parasites in Ethiopia, and the results differ and are inconsistent from one region to another. Thus, the goal of this systematic review and meta-analysis was to ascertain Ethiopia's pooled prevalence of P. falciparum and S. mansoni coinfection.

METHODS

The preferred reporting item review and meta-analysis guidelines were followed in this study. PubMed, Google Scholar, Research4Life, Scopus, African-Wider, and EMBASE were the primary search databases. The final analysis included six studies in total. Stata software version 11 was used for analysis after Microsoft Excel was used to extract the data. The critical appraisal tool developed by the Joanna Briggs Institute was used to evaluate the methodological quality of the studies. Publication bias was checked via a funnel plot, Begg's test, and Egger's test. The pooled prevalence of P. falciparum and S. mansoni coinfection was estimated via a random effect model via the Der Simonian-Laird method. The heterogeneity of the studies was evaluated via I2 statistical tests.

RESULTS

The pooled prevalence of P. falciparum and S. mansoni coinfections in Ethiopia was 10.496% (95% CI 6.134, 14.859). Subgroup analysis of geopolitical regions revealed that the highest and lowest pooled prevalence rates of coinfection were 11.808% (95% CI 0.304, 23.312) and 8.600% (95% CI 5.755, 11.445), respectively, in the Amhara and Benishangul Gumuz regions.

CONCLUSIONS

This study highlights the substantial prevalence of P. falciparum and S. mansoni coinfection in Ethiopia's general population, with considerable geographical variation. Targeted and intensive public health interventions are necessary because it has the highest incidence in the Amhara region, and ongoing efforts are needed to address the relatively lower but still considerable prevalence in the Benishangul Gumuz region. These results direct future research, integrated control strategy design, and resource allocation to successfully manage Ethiopia's combined burden of malaria and schistosomiasis.

Waning success: a 2013-2022 spatial and temporal trend analysis of malaria in Ethiopia

BACKGROUND

Despite consecutive decades of success in reducing malaria transmission, Ethiopia went off track towards its goal of malaria elimination by 2030, as outlined in the NMCP malaria strategy. Recent malaria outbreaks in Ethiopia are attributed to the emergence and spread of diagnostic and drug-resistant Plasmodium falciparum, increased insecticide resistance in major vectors and the spread of invasive Anopheles stephensi. The effects of the COVID-19 pandemic, environmental anomalies and internal conflicts have also potentially played a role in increasing malaria transmission. This study aimed to evaluate the contribution of environmental factors and An. stephensi to the spatiotemporal trends of recent malaria cases in Ethiopia.

METHODS

Clinical malaria case data reported weekly between January 2013 and January 2023 were obtained from the Ethiopian Public Health Institute (EPHI), Addis Ababa. A negative binomial regression model was used to explain the variability and potential overdispersion in the weekly number of malaria cases reported across Ethiopian administrative zones. This model incorporated fixed effects for selected environmental factors and random effects to capture temporal trends, zone specific seasonal patterns, spatial trends at the zone level, and the presence of An. stephensi and its impact.

RESULTS

Our negative binomial regression model highlighted 56% variability in the data and slightly more than half (55%) was due to environmental factors, while the remainder was captured by random effects. A significant nationwide decline in malaria risk was observed between 2013 and 2018, followed by a sharp increase in early 2022. Malaria risk was higher in western and northwestern zones of Ethiopia compared to other zones. Zone-specific seasonal patterns, not explained by environmental factors, were grouped into four clusters of seasonal behaviours. The presence of An. stephensi was not shown to have any significant impact on malaria risk.

CONCLUSIONS

Understanding the spatial and temporal drivers of malaria transmission and therefore identifying more appropriate malaria control strategies are key to the success of any malaria elimination and eradication programmes in Ethiopia. Our study found that approximately 50% of malaria risk variability could be explained by environmental, temporal, and spatial factors included in the analysis, while the remaining variation was unexplained and may stem from other factors not considered in this study. This highlights the need for a better understanding of underlying factors driving local malaria transmission and outbreaks, to better tailor regional programmatic responses.

Treatment outcomes and associated factors in severe malaria patients at University of Gondar Hospital, Northwest Ethiopia: A retrospective study (2020-2023)

BACKGROUND

Malaria continues to be the most prevalent life-threatening parasitic illness in Ethiopia. Its clinical spectrum ranges from mild to severe, with a propensity for death. In Ethiopia, it accounts for 10% of hospital admission. Identifying predictors of malaria-related mortality is crucial for aiding high-risk patient identification and enabling timely intervention.

OBJECTIVE

Our study aimed to assess treatment outcomes and factors associated with mortality among severe malaria patients at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia.

METHODS

A retrospective cross-sectional study examined 383 randomly chosen patients with severe malaria, spanning a four-year period leading up to the data collection date, encompassing July 2023 back to June 2020. Data were collected from the hospital records. A structured questionnaire was used to collect the data. EpiData version 3.1 and SPSS version 20 were used to clean and analyze the data, respectively. Logistic regression analysis was conducted to determine associations and reported by the odds ratio at p < 0.05 with 95% confidence intervals.

RESULTS

Among the 383 eligible patients, the majorities were males (56.66%) and resided in rural areas (66.32%). Over 84% of them were referred from health facilities. Plasmodium falciparum was the major parasite identified in 78% of cases. The magnitude of death among severe malaria patients was 10.97%. Impaired consciousness, convulsions, jaundice, parasitemia level >2, and creatinine level ≥3 were significantly associated with death, with adjusted odds ratios (AOR) of 3.4 (95% CI: 1.3-8.3), 2.7 (95% CI: 1.004-7.492), 3.2 (95% CI: 1.173-9.182), 3.7 (95% CI: 1.516-9.113), and 11.7 (95% CI: 4.756-29.239), respectively.

CONCLUSION

Our study revealed a significant number of malaria-related deaths, with predictors such as age, impaired consciousness, convulsions, jaundice, parasitemia level, and creatinine level identified. Hence, it is imperative to implement intense and timely interventions for patients exhibiting these clinical manifestations to prevent malaria-related fatalities.

Effect of seasonal variability on the increased malaria positivity rate in drought-prone malaria endemic areas of Ethiopia

Malaria is a climate-sensitive and season-dependent disease that mainly affects the populations of tropical and subtropical regions of the world. Climatic variables such as rainfall, temperature, and humidity are identified as the driving factors affecting the epidemiology of malaria. In Ethiopia, recently unexpectedly high malaria burden accompanied by substantial morbidity and mortality is observed. The incidence rate of vector-borne diseases such as malaria is largely influenced by fluctuation of seasonal variables due to the proceeding global warming. Therefore, the study aimed to assess the impact of seasonal and climate variability on the burden of malaria in one of drought-prone areas of north central Ethiopia. The study was conducted in the Oromia zone of the Amhara regional state in Ethiopia. Data from patients tested and diagnosed with malaria between 2014 and 2019 were extracted from the medical records of the patients registered in all health facilities found in the zone. Additionally, meteorological data such as rainfall and temperature (maximum and minimum) were collected from the regional meteorological agency. Data were analyzed using R software. The malaria positivity rate recorded in this study was 12.7% (64,522/508,057). Months from June to December were significantly (p < 0.05) associated with high malaria positivity. Rainfall had a significant negative effect on malaria positivity (p = 0.042). Also, three to four months of lagged rainfall is associated with high malaria positivity (p < 0.05). However, monthly minimum temperature positivity influenced the rate of malaria positivity (exp = 0.037, p = 0.0098). While monthly mean maximum temperature showed a negative association with malaria positivity, although it was insignificant. In addition, malaria positivity significantly decreased from 2014 to 2019 by 20.5% (exp = 0.205, p < 0.0001). The seasonal and climatic variables evaluated in this study substantially affected the malaria positivity rate. Monthly mean temperature was the leading and predictor variable for malaria infection. Despite vigorous efforts by health authorities in the country at this level, following the neglected implementation of interventional activities in the nation for a couple of years, malaria-associated burdens have increased. As seasonal and climate variables could play a key role in the rising burden, concerned national or local health authorities, and policymakers should prioritize urgent interventional activities to control malaria in one of the drought-prone areas of Ethiopia.

A survey of malaria vectors feeding preference, biting site and resting behaviour in the malaria elimination settings of Dembiya District, north-western Ethiopia

BACKGROUND

Despite the progress in scaling vector control interventions in Ethiopia, malaria is still a major health problem in the country. Monitoring of the local vector populations and the effectiveness of vector control strategies is necessary to guide programme decisions to optimize malaria prevention efforts. This study investigated the feeding preference, the biting behaviour and resting behaviours of Anopheles mosquitoes in selected localities of Dembiya District.

METHODS

Adult Anopheles mosquitoes were sampled indoors and outdoors from June 2018 to May 2019 using CDC light traps, pyrethrum spray catches, artificial pit shelters, and mouth aspirators at both Guramba Bata and Arebiya study sites. Anopheles mosquitoes were identified to the species level. Their blood meal source and Plasmodium sporozoite infections were determined using an enzyme-linked immunosorbent assay.

RESULTS

Anopheles mosquitoes belonging to 11 species were identified from 2,055 collected mosquito specimens. Anopheles pharoensis was the predominant species at both the Guramba Bata (46.5%) and Arebiya (46.2%) study sites. The CDC light traps caught the highest number of Anopheles mosquitoes in both study sites. In Guramba Bata the density of outdoor host-seeking and resting Anopheles mosquitoes were higher than indoors (P ≤ 0.05). The human blood indexes (HBI) of indoor and outdoor host-seeking Anopheles arabiensis were 17.4% and 15.3%, respectively. The entomological inoculation rate (EIR) of outdoor host-seeking An. arabiensis was 4.7 infective bites/person/year. Additionally, the outdoor EIR of host-seeking Anopheles coustani was 25.7ib/p/year.

CONCLUSIONS

Anopheles mosquitoes in Dembiya district were more likely to seek a host and rest outdoors than indoors. A reevaluation of vector control strategies is needed to ensure Ethiopia remains on the path to malaria elimination. The detection of Plasmodium circumsporozoite protein in potential secondary vectors, such as An. coustani requires further investigation to substantiate their role in malaria transmission.

High Prevalence of Pfhrp2/3 Gene Deletions and Major Threat to Malaria Control Programs in Ethiopia

Background: Rapid diagnostic tests (RDTs) targeting pfhistidine-rich protein 2 (Pfhrp2) are widely used for diagnosis of Plasmodium falciparum infections in resource-limited malaria endemic countries. However, test results are affected by deletions of the Pfhrp2, Pfhrp3, and flanking genes and associated negative results from rapid diagnostic devices were previously reported. Therefore, the aim of this study was to reveal the existing genetic profile of Pfhrp2 and Pfhrp3 genes of P. falciparum-infected patients in northwestern Ethiopia. Methods: A total number of 302 blood samples were collected from children at Chilga (Aykel, Negade Bahir), and Sanja health centers in northwestern Ethiopia. Thirty-three (10.9%) samples tested positive for P. falciparum malaria. The Pfhrp2, Pfhrp3, and flanking genes (MAL7P1_228 and MAL7P1_230 for Pfhrp2, and MAL13P1_475 and MAL13P1_485 for Pfhrp3) were amplified using standard nested-PCR. Results: Pfhrp2 and both of its flanking genes were found to be present in 12 (36.4%) out of the 33 samples. Twenty-one (63.6%) samples tested negative for the Pfhrp2 gene and 19 samples (57.6%) tested positive for at least one of the flanking genes. Five (15.2%) samples gave positive results for the Pfhrp3 gene and both of its flanking genes, whereas 16 (48.5%) tested negative for all three. Conclusions: Our study provides widespread deletions in the Pfhrp2 and Pfhrp3 genes in Ethiopia, thereby confirming anecdotal reports of diagnostic failure with Pfhrp2-based RDTs in the region. The implications of our finding for the current diagnostic paradigm, which relies on the detection of P. falciparum by Pfhrp2-based RDTs in remote areas, may need rethinking.

Long Lasting Insecticide-Treated Nets Utilization and Associated Factors Among Pregnant Women in Shebel Berenta District, Northwest Ethiopia

Background

Insecticide-treated bed nets are cost-effective vector control methods for malaria prevention. Malaria during pregnancy poses a significant health problem in Ethiopia. This study aimed to assess insecticide-treated nets utilization and associated factors among pregnant women in Shebel Berenta District, Northwest Ethiopia.

Objective

To assess insecticide-treated bed nets utilization and associated factors among pregnant women in Shebel Berenta District, Northwest Ethiopia, in 2023.

Methods

A community-based cross-sectional study was conducted from March 15 to April 30, 2023, on 505 randomly selected pregnant women. Data were collected using a pre-tested structured questionnaire and observational checklist, analyzed with EpiData 3.1 and SPSS 25. Significant factors associated with long-lasting insecticide-treated nets were identified (P < .05, 95% CI) and were reported as statistically significant factors associated with the utilization of insecticide-treated bed nets.

Results

The utilization of long-lasting insecticide-treated nets was 45.10% [95% CI: 40.5%-49.2%]. Mothers who had antenatal care follow-up (AOR = 3.359; 95%CI: 1.829, 6.166), mothers with illiterate educational status (AOR = 0.196; 95%CI: 0.064-0.603), and mothers who had received information (message) (AOR = 8.102; 95%CI: 3.942-16.653) were significantly associated with long lasting insecticide-treated net utilization.

Conclusion

Utilization of long lasting insecticide-treated nets by pregnant women was 45.1%, which was lower than the WHO standard. Attending antenatal care, receiving information (messages) about malaria and long lasting insecticide-treated net, and mother's being literate had a substantial impact on long lasting insecticide-treated net utilization. Therefore, efforts should be made to strengthen ANC service, health information and women's educational status to increase utilization of long lasting insecticide-treated nets.

Barriers of persistent long-lasting insecticidal nets utilization in Northwest Ethiopia: a qualitative study

BACKGROUND

Malaria continues a significant public health challenge in Ethiopia, with Long-Lasting Insecticidal Nets (LLINs) proving effective in reducing transmission. Despite their effectiveness, consistent LLIN utilization is influenced by various factors. While previous research has quantitatively analyzed LLIN ownership and usage, there is a lack of in-depth examination of the behavioral, sociocultural, socioeconomic, and distribution-related factors affecting their sustained use. This study aimed to explore barriers to persistent LLIN use among communities in northwest Ethiopia.

METHODS

The study area found in Northwest Ethiopia, specifically in East Belessa District, is located at 12° 14' 60.00" N latitude and 37° 44' 59.99" E longitude, with an altitude between 1,200 and 1,800 m above sea level. Thirty-nine community members from five focus group discussions, along with five key informants, were interviewed between February 1st and 30th, 2020, about their use of Long-Lasting Insecticidal Nets (LLINs). An interpretive description approach was employed to explore local contexts and factors affecting LLIN utilization. Focus group participants were selected based on residency status, pregnancy, caretaking of under-five children, and experience with LLINs. Key informants included health extension workers and the woreda malaria officer. Data were organized and analyzed using Open Code Version 4.03 software, with coding and theme identification conducted accordingly.

RESULTS

All 44 community members from the five focus group discussions and the five key informants participated fully in the study. The study categorized its findings into three main themes: knowledge of malaria and Long-Lasting Insecticidal Nets (LLIN) use, perception of malaria threat, and barriers to sustained LLIN utilization. It identified factors spanning individual, socio-cultural, institutional, and socio-economic realms that impede consistent LLIN usage. Key hindrances include cultural misinterpretations, discomfort from heat and bed bugs, diverse net shapes, insufficient sleeping spaces, lack of awareness, inadequate distribution, neglect of vulnerable groups, misuse of non-sleeping purposes, hesitancy to hang nets, and restricted accessibility.

CONCLUSIONS

This study reveals that practical concerns, including inadequate access to LLINs, distribution issues, discomfort from net shape and warmth, and unintended uses for non-malaria purposes, impact LLIN utilization. Socio-cultural norms, housing conditions, and varied understanding of malaria also contribute to inconsistent LLIN use. Strategies like providing compatible nets and comprehensive education could improve the Long-Lasting Insecticidal Nets program's effectiveness in the area.

Urban malaria and its determinants in Eastern Ethiopia: the role of Anopheles stephensi and urbanization

BACKGROUND

Malaria prevention and control strategies have been hampered by urbanization and the spread of Anopheles stephensi. The spread of this vector into Africa further complicates the already complex malaria situation, that could put about 126 million Africans at risk of infection. Hence, this study aimed to assess the determinants of urban malaria, focusing on the role of urbanization and the distribution of An. stephensi in Eastern Ethiopia.

METHODS

A matched case control study was conducted among febrile urban residents of Dire Dawa (malaria positive as cases and negative as a control). A capillary blood sample was collected for parasite identification using microscopic examination and an interviewer administered questionnaire was used to collect additional data. Centers for Disease Control and Prevention miniature light traps (CDC-LT) and Prokopack aspirator were used to collect adult mosquito vectors from the selected cases and control houses to identify the mosquito vector species. Then, the data were exported to STATA for analysis. Conditional logistic regression was done to identify determinants, and principal component Analysis (PCA) was done for some independent variables.

RESULTS

This study enrolled 132 cases and 264 controls from urban setting only. Of the 132 cases, 90 cases were positive for Plasmodium falciparum, 34 were positive for Plasmodium vivax and 8 had mixed infections. All cases and controls were similar with regard to their respective age and sex. Travel history (AOR: 13.1, 95% CI 2.8-61.4), presence of eves and holes on walls (AOR: 2.84, 95% CI 1.5-5.5), history of malaria diagnosis (AOR: 2.4, 95% CI 1.1-5.3), owning any livestock (AOR: 7.5, 95% CI 2.4-22.8), presence of stagnant water in the area (AOR: 3.2, 95% CI 1.7-6.1), sleeping under bed net the previous night (AOR: 0.21, 95% CI 0.1-0.6) and knowledge on malaria and its prevention (AOR: 2.2, 95% CI 1.2-4.1) were determinants of urban malaria infection. About 34 adult Anopheles mosquitoes were collected and identified from those selected cases and control houses and 27 of them were identified as An. stephensi.

CONCLUSION

Among the cases, the dominant species were P. falciparum. This study identified travel history, house condition, past infection, livestock ownership, stagnant water, bed net use, and malaria knowledge as determinants of infection. This study also found the dominance of the presence of An. stephensi among the collected mosquito vectors. This suggests that the spread of An. stephensi may be impacting malaria infection in the study area. Hence, strengthening urban-targeted malaria interventions should be enhanced to prevent and control further urban malaria infection and spread.

Plasticity of blood feeding behavior of Anopheles mosquitoes in Ethiopia: a systematic review

BACKGROUND

The efficacy of vector control tools depends on the behavior of the vector species. Many studies have sought to determine the feeding behavior of Anopheles mosquitoes in different settings of Ethiopia. We have performed a systematic review aimed to generate pooled evidence on the overall and species-specific blood meal sources of Anopheles mosquitoes in Ethiopia.

METHODS

A search for relevant articles was performed in two electronic databases (PubMed and Science Direct) and three search engines (Google Scholar, Research Gate and Google) between 11 March and 2 April 2024. Following the initial identification of articles, we used EndNote X8 software and removed duplicate articles and screened the remaining articles by careful reading of their titles and abstracts. The full text of articles that passed this screening phase was retrieved, read and evaluated against predetermined selection criteria. The final decision for inclusion in the systematic review was made after a methodological quality check using the JBI critical appraisal checklist. All relevant data were extracted from tables, figures and texts of the included articles using a premade template in Excel, and the data were analyzed using Stata version 14 software.

RESULTS

Of the 2431 studies identified, 27 met the inclusion criteria; all were published between 1997 and 2024. At 215 data points (frequency of tests of each Anopheles species by location and method of mosquito collections), 18,771 Anopheles mosquitoes belonging to 23 species or species complexes were tested for blood meal sources. The commonest sources of blood meals for Anopheles mosquitoes were bovine (36.0%, n = 6758) and human (29.4%, n = 5520). Among the tested anophelines, Anopheles (An.) arabiensis accounted for 67.9% (n = 12,741), followed by An. pharoensis, An. demeilloni and An. stephensi at 10.0%, 5.6% and 4.4%, respectively. Overall, there was no difference in the mean proportion of An. arabiensis detected with domestic animal blood (33.4%, 95% confidence interval [CI] 32.4-34.4%) and those detected with human blood (31.8%, 95% CI 30.9-32.8%). However, a greater proportion of the outdoor collected An. arabiensis were found to feed on bovines (47.9%, 95% CI 35.3-60.6) compared to humans (12.9%, 95% CI 0.8-24.9, P < 0.01). The foraging ratio (FR), which accounts for host availability, was greater for bovines (FR = 0.7) than for humans (FR = 0.2) for An. arabiensis, indicating preferential feeding on bovine hosts. This host preference was supported by the host preference index (human:bovine = 0.4). Anopheles pharoensis was detected with a slightly higher human blood index (53.5%, n = 1005) compared to bovine blood index (45.2%, n = 849). In contrast, An. demeilloni, An. coustani and An. marshalli were detected with a higher bovine blood index. Recently invaded urban malaria vector, An. stephensi was found with a higher ovine blood index.

CONCLUSIONS

Bovine and human hosts are common sources of a blood meal for Anopheles mosquitoes. In terms of host availability, An. arabiensis showed preferential feeding on bovines/cattle. Targeting domestic animals, bovines and ovines with endectocides could supplement current vector control interventions.

STUDY REGISTRATION

The protocol of this study was registered on the International Prospective Register of Systematic Reviews, registration no. CRD42024515725.

Seasonal Dynamics of Symptomatic and Asymptomatic Plasmodium falciparum and Plasmodium vivax Infections in Coendemic Low-Transmission Settings, South Ethiopia

Ethiopia has a plan to eliminate malaria in selected low-transmission districts by 2025. However, complex factors such as seasonality, focal heterogeneity, and coendemicity of Plasmodium vivax and Plasmodium falciparum, and asymptomatic cases, along with other factors, pose challenges. This longitudinal study assessed these dynamics and associated factors in three elimination-targeted settings in southern Ethiopia. The study included rural districts (Wonago and Yirgacheffe) and an urban setting (Dilla town) with 504 participants from 168 households per season. The study covered the peak and minor malaria transmission seasons and the dry season. Finger-prick blood was collected for microscopy, rapid diagnostic tests, and 18S-rRNA-based quantitative polymerase chain reaction (qPCR). During the dry season, P. vivax accounted for most infections (64.5%, 71/110) and symptomatic malaria (50.9%, 29/57), whereas P. falciparum dominated during the peak transmission season (45.7%, 42/92 infections and 58.1%, 25/43 of symptomatic cases). Treatment-seeking behavior was low, with 65.3% (143/219) of symptomatic individuals not seeking treatment. Dilla town had significantly higher infection prevalence (29.6%, 149/504, P <0.001) in all seasons compared with the rural sites. The incidence rate was 12/1,000 person-seasons by qPCR and 5/1,000 person-seasons by microscopy. Urban residents, those with low hemoglobin levels, nonuse of mosquito nets, and proximity to stagnant water had a significantly higher risk of infection (P <0.001). Tailored approaches are needed in elimination-targeted areas, focusing on urban settings, Plasmodium species, and strengthening community-level interventions for behavioral change and active case detection.

Resurgence of Clinical Malaria in Ethiopia and Its Link to Anopheles stephensi Invasion

The invasion of Anopheles stephensi into Africa poses a potential threat to malaria control and elimination on the continent. However, it is not clear if the recent malaria resurgence in Ethiopia has linked to the expansion of An. stephensi. We obtained the clinical malaria case reports and malaria intervention data from the Ethiopian Ministry of Health (MoH) for the period 2001-2022. We analyzed clinical malaria hotspots and investigated the potential role of An. stephensi in the 2022 malaria outbreaks. Clinical malaria cases in Ethiopia decreased by 80%, from 5.2 million cases in 2004 to 1.0 million cases in 2018; however, cases increased steadily to 2.6 million confirmed cases in 2022. Plasmodium vivax cases and proportion have increased significantly in the past 5 years. Clinical malaria hotspots are concentrated along the western Ethiopian border areas and have grown significantly from 2017 to 2022. Major malaria outbreaks in 2022/2023 were detected in multiple sites across Ethiopia, and An. stephensi was the predominant vector in some of these sites, however, it was absence from many of the outbreak sites. The causes of recent upsurge in malaria in Ethiopia may be multi-factorial and it is a subject of further investigation.

Resurgence of Clinical Malaria in Ethiopia in the Era of Anopheles stephensi Invasion

Background

The invasion of Anopheles stephensi into Africa poses a potential threat to malaria control and elimination on the continent. However, it is not clear if the recent malaria resurgence in Ethiopia has linked to the expansion of An. stephensi. We aimed to summarize the major achievements and lesson learnt in malaria control in Ethiopia from 2001 to 2022, to assess the new challenges and prospects for the control of An. stephensi.

Methods and findings

We obtained the clinical malaria case reports, antimalarial drug treatment records, insecticide-treated and long-lasting insecticidal net (ITN/LLIN) distribution and utilization records, and indoor residual spraying (IRS) coverage data from the Ethiopian Ministry of Health (MoH) for the period 2001-2022. We analyzed clinical malaria hotspots using spatially optimized hotspot analysis. We investigated malaria outbreaks in 2022 and examined the potential role of An. stephensi in the outbreaks.Clinical malaria cases in Ethiopia decreased by 80%, from 5.2 million cases (11% confirmed) in 2004 to 1.0 million cases (92% confirmed) in 2018; however, cases increased steadily to 2.6 million confirmed cases (98% confirmed) in 2022. Plasmodium vivax cases and proportion have increased significantly in the past 5 years. Clinical malaria hotspots are concentrated along the western Ethiopian border areas and have grown significantly from 2017 to 2022. Major malaria outbreaks in 2022/23 were detected in multiple sites across Ethiopia, and An. stephensi was the predominant vector in some of these sites, however, it was absence from many of the outbreak sites.

Conclusions

The malaria burden has been significantly reduced in Ethiopia in the past two decades, but in recent years it has increased substantially, and the cause of such increase is a subject of further investigation. Major gaps exist in An. stephensi research, including vector ecology, surveillance, and control tools, especially for adult mosquito control.

Malaria Prevalence and Risk Factors in Outpatients at Teda Health Center, Northwest Ethiopia: A Cross-Sectional Study

Background

Despite extensive efforts and achievements made in prevention and control, malaria is still a public health problem in Ethiopia. Currently, the case number has been climbing, even changing the epidemiology to the previously low-burden reporting locations. Therefore, our study is aimed at assessing malaria prevalence and associated risk factors in outpatients, Northwest Ethiopia.

Methods

A facility-based cross-sectional study was conducted among 318 malaria-suspected outpatients from October 22 to December 15, 2022, at Teda Health Center, Northwest Ethiopia. Sociodemographic characteristics and malaria risk factors were assessed by a face-to-face interview using a pretested questionnaire. Plasmodium parasites were detected by using microscopy on a blood film stained with 10% and 3% Giemsa stain. The data were analyzed using Statistical Package for Social Sciences software version 25, and statistical significance was reported at a p value < 0.05.

Results

Of the 318 study participants, 124 (39.0%; 95%CI = 33.6% - 44.6%) tested positive for Plasmodium infection. Plasmodium vivax, P. falciparum, and mixed infections were identified in 71 (57.3%), 47 (37.9%), and 6 (4.8%), respectively, among positive study participants. Individuals above the age of 15 (AOR = 2.704, 95% CI 1.370-5.336) were more likely to be infected with Plasmodium than under-five-year-old individuals. Rural residents (AOR = 2.56, 95% CI 1.281-5.098), those who sleep or work outside at night (AOR = 1.99, 95% CI 1.020-3.875), and individuals who did not use long-lasting insecticide-treated net (AOR = 3.26, 95% CI 1.633-6.499) and had a family member with a history of malaria (AOR = 2.902, 95%CI = 1.671 - 5.041) had higher odds of acquiring Plasmodium infection than their counterparts.

Conclusion

In our study area, malaria was a major health problem, with P. vivax being the dominant species. Multiple environmental and behavioural factors were associated with the infection acquisition. Therefore, urgent holistic intervention is required.

Exploring coagulation parameters as predictive biomarkers of Plasmodium infection: A comprehensive analysis of coagulation parameters

BACKGROUND

Malaria affects the intravascular environment, leading to abnormal coagulation activation, prolonged prothrombin time, and activated partial thromboplastin time. Despite the high prevalence of malaria in the study area, there has been little published research on the effects of Plasmodium infection on coagulation parameters.

OBJECTIVE

The aim was to assess the effect of malaria on basic coagulation parameters among patients attending Dembia Primary Hospital and Makisegnit Health Center.

METHODS

A cross-sectional study was carried out from January to March 2020. The study involved 120 participants. Blood specimens were collected, which were analyzed using a Huma Clot Due Plus analyzer. The collected data were entered into EpiData and exported to SPSS version 21 for analysis. Non-parametric statistical methods were employed to analyze the data. The results were considered statistically significant if the p-value was less than 0.05.

RESULTS

Individuals infected with Plasmodium exhibit coagulation disorders with elevated levels of PT (Prothrombin Time), APTT (Activated Partial Thromboplastin Time), and INR (International Normalization Ratio) in comparison to healthy controls. The median PT, APTT, and INR values for infected cases were measured at 20.5 [8.6], 39.5 [17.9], and 1.8 [0.9], respectively, while healthy controls had measurements of 15.1 [2.5], 28.8 [8.3], and 1.3 [0.2] (p ≤ 0.001). The severity of coagulation disorders increased with an increase in parasitemia levels. The type of Plasmodium species present had a significant impact on PT and INR values (p ≤ 0.001), whereas APTT did not show any significant impact across the Plasmodium species (p > 0.05).

CONCLUSION

The results of this study found that malaria has a substantial impact on various blood clotting parameters, including PT, APTT, and INR. Parasitemia severity is significantly associated with extended PT and INR, implying that the higher the parasitemia, the longer it takes for blood to clot. Furthermore, the study discovered that the PT and INR levels differed based on the type of Plasmodium species responsible for the infection.

Spatiotemporal distribution and bionomics of Anopheles stephensi in different eco-epidemiological settings in Ethiopia

BACKGROUND

Malaria is a major public health concern in Ethiopia, and its incidence could worsen with the spread of the invasive mosquito species Anopheles stephensi in the country. This study aimed to provide updates on the distribution of An. stephensi and likely household exposure in Ethiopia.

METHODS

Entomological surveillance was performed in 26 urban settings in Ethiopia from 2021 to 2023. A kilometer-by-kilometer quadrant was established per town, and approximately 20 structures per quadrant were surveyed every 3 months. Additional extensive sampling was conducted in 50 randomly selected structures in four urban centers in 2022 and 2023 to assess households' exposure to An. stephensi. Prokopack aspirators and CDC light traps were used to collect adult mosquitoes, and standard dippers were used to collect immature stages. The collected mosquitoes were identified to species level by morphological keys and molecular methods. PCR assays were used to assess Plasmodium infection and mosquito blood meal source.

RESULTS

Catches of adult An. stephensi were generally low (mean: 0.15 per trap), with eight positive sites among the 26 surveyed. This mosquito species was reported for the first time in Assosa, western Ethiopia. Anopheles stephensi was the predominant species in four of the eight positive sites, accounting for 75-100% relative abundance of the adult Anopheles catches. Household-level exposure, defined as the percentage of households with a peridomestic presence of An. stephensi, ranged from 18% in Metehara to 30% in Danan. Anopheles arabiensis was the predominant species in 20 of the 26 sites, accounting for 42.9-100% of the Anopheles catches. Bovine blood index, ovine blood index and human blood index values were 69.2%, 32.3% and 24.6%, respectively, for An. stephensi, and 65.4%, 46.7% and 35.8%, respectively, for An. arabiensis. None of the 197 An. stephensi mosquitoes assayed tested positive for Plasmodium sporozoite, while of the 1434 An. arabiensis mosquitoes assayed, 62 were positive for Plasmodium (10 for P. falciparum and 52 for P. vivax).

CONCLUSIONS

This study shows that the geographical range of An. stephensi has expanded to western Ethiopia. Strongly zoophagic behavior coupled with low adult catches might explain the absence of Plasmodium infection. The level of household exposure to An. stephensi in this study varied across positive sites. Further research is needed to better understand the bionomics and contribution of An. stephensi to malaria transmission.

Ethnobotanical Study of Mosquito Repellent Plants Used in Seweyna District, Bale Zone, Southeast, Ethiopia

Malaria control efforts through vector control strategies are hindered by the development of insecticide resistance by major malaria vectors in many malaria-endemic areas, which necessitate the need for alternative control measures. The aim of this study was to document plants traditionally used as mosquito repellents in Seweyna district, southeastern Ethiopia. The ethnobotanical data were collected using semistructured interviews, field observation, and guided field walks in four kebeles of the district with 98 informants. A total of 19 plant species were used by the local community as mosquito repellent, with 42.1% being trees. These plant species belong to 12 families. Of these families, the family Burseraceae was the most represented, with four species, followed by Fabaceae (3 species). The most frequently mentioned plant species were Mimusops kummel (90.81%), followed by Acokanthera schimperi (84.69%), Boswellia microphylla (79.6%), and Calpurnia aurea (79.6%). The stem was the most common plant part used (47.3%) to repel mosquitoes. Most of the local communities (52.6%) use the burning of either fresh or dry plant parts to generate smoke, which is the most common practice. The current ethnobotanical study indicates that the local community in the Seweyna district uses the plants to repel mosquitoes. In the future, the repellent efficacy of these plants against the major malaria vector should be tested under laboratory and field conditions. Besides, the identification of the bioactive compounds responsible for the repellent activity should also be determined.

Epidemiology of Plasmodium vivax in Duffy negatives and Duffy positives from community and health centre collections in Ethiopia

BACKGROUND

Malaria remains a significant cause of morbidity and mortality in Ethiopia with an estimated 3.8 million cases in 2021 and 61% of the population living in areas at risk of malaria transmission. Throughout the country Plasmodium vivax and Plasmodium falciparum are co-endemic, and Duffy expression is highly heterogeneous. The public health significance of Duffy negativity in relation to P. vivax malaria in Ethiopia, however, remains unclear. This study seeks to explore the prevalence and rates of P. vivax malaria infection across Duffy phenotypes in clinical and community settings.

METHODS

A total of 9580 and 4667 subjects from community and health facilities from a malaria endemic site and an epidemic-prone site in western Ethiopia were enrolled and examined for P. vivax infection and Duffy expression from February 2018 to April 2021. Association between Duffy expression, P. vivax and P. falciparum infections were examined for samples collected from asymptomatic community volunteers and symptomatic subjects from health centres.

RESULTS

Infection rate of P. vivax among Duffy positives was 2-22 fold higher than Duffy negatives in asymptomatic volunteers from the community. Parasite positivity rate was 10-50 fold higher in Duffy positives than Duffy negatives among samples collected from febrile patients attending health centres and mixed P. vivax and P. falciparum infections were significantly more common than P. vivax mono infections among Duffy negative individuals. Plasmodium vivax parasitaemia measured by 18sRNA parasite gene copy number was similar between Duffy positives and Duffy negatives.

CONCLUSIONS

Duffy negativity does not offer complete protection against infection by P. vivax, and cases of P. vivax in Duffy negatives are widespread in Ethiopia, being found in asymptomatic volunteers from communities and in febrile patients from health centres. These findings offer evidence for consideration when developing control and intervention strategies in areas of endemic P. vivax and Duffy heterogeneity.

Plasmodium falciparum transmission in the highlands of Ethiopia is driven by closely related and clonal parasites

Malaria cases are frequently recorded in the Ethiopian highlands even at altitudes above 2000 m. The epidemiology of malaria in the Ethiopian highlands, and, in particular, the role of importation by human migration from the highly endemic lowlands is not well understood. We sequenced 187 Plasmodium falciparum samples from two sites in the Ethiopian highlands, Gondar (n = 159) and Ziway (n = 28), using a multiplexed droplet digital PCR (ddPCR)-based amplicon sequencing method targeting 35 microhaplotypes and drug resistance loci. Here, we characterize the parasite population structure and genetic relatedness. We identify moderate parasite diversity (mean HE : 0.54) and low infection complexity (74.9% monoclonal). A significant percentage of infections share microhaplotypes, even across transmission seasons and sites, indicating persistent local transmission. We identify multiple clusters of clonal or near-clonal infections, highlighting high genetic relatedness. Only 6.3% of individuals diagnosed with P. falciparum reported recent travel. Yet, in clonal or near-clonal clusters, infections of travellers were frequently observed first in time, suggesting that parasites may have been imported and then transmitted locally. 31.1% of infections are pfhrp2-deleted and 84.4% pfhrp3-deleted, and 28.7% have pfhrp2/3 double deletions. Parasites with pfhrp2/3 deletions and wild-type parasites are genetically distinct. Mutations associated with resistance to sulphadoxine-pyrimethamine or suggested to reduce sensitivity to lumefantrine are observed at near-fixation. In conclusion, genomic data corroborate local transmission and the importance of intensified control in the Ethiopian highlands.

Anopheles arabiensis continues to be the primary vector of Plasmodium falciparum after decades of malaria control in southwestern Ethiopia

BACKGROUND

Investigating the species distribution and their role in malaria transmission is important as it varies from place to place and is highly needed to design interventions appropriate to the site. The current study aimed to investigate the Anopheles mosquito species distribution and their infection rate in southwestern Ethiopia.

METHODS

The study was conducted in 14 malaria-endemic kebeles (the smallest administrative unit), which were situated in eight different malaria-endemic districts and four zones in southwestern Ethiopia. Ten per cent of households in each village were visited to collect adult mosquitoes using Centers for Disease Control and Prevention (CDC) light traps. The larval and pupal collection was done from breeding sites within the villages, and reared to adults. Female mosquitoes were morphologically identified. The head and thorax of adult Anopheles mosquitoes were tested for circumsporozoite proteins (CSPs) using ELISA. At the same time, legs, wings, and abdomen were used to identify sibling species using PCR targeting the rDNA intergenic spacers region for species typing of the Anopheles funestus group and the internal transcribed spacer 2 region genes for Anopheles gambiae complex.

RESULTS

A total of 1445 Anopheles mosquitoes comprising eight species were collected. Of 813 An. gambiae complex tested by PCR, 785 (97%) were Anopheles arabiensis, and the remaining 28 (3%) were not amplified. There were 133 An. funestus group captured and tested to identify the species, of which 117 (88%) were positive for Anopheles parensis, and 15 (11%) were not amplified. A single specimen (1%) showed a band with a different base pair length from the known An. funestus group species. Sequencing revealed this was Anopheles sergentii. Among 1399 Anopheles tested for CSPs by ELISA, 5 (0.4%) An. arabiensis were positive for Plasmodium falciparum and a single (0.07%) was positive for Plasmodium vivax.

CONCLUSIONS

Anopheles arabiensis continues to play the principal role in malaria transmission despite implementing indoor-based interventions for decades. Sequencing results suggest that An. sergentii was amplified by the An. funestus group primer, producing PCR amplicon size of different length. Therefore, relying solely on amplifying a specific gene of interest in grouping species could be misleading, as different species may share the same gene.

Plasmodium falciparum remains the dominant parasite affecting children despite decades of implementing vector control in two villages of Wolaita Zone, Southwest Ethiopia

Background

Malaria is still a significant public health concern, and its prevention and control measures have different impacts in different areas. This study assesses the prevalence of malaria and the effectiveness of routine malaria control programmes such as indoor residual spray (IRS) in two Ethiopian villages.

Methods

The Kebeles (villages) were purposefully selected based on their malaria prevalence rates. A parasitology survey was conducted in Fango-Gelchecha pre- and post-IRS implementation, whereas in Shochora-Abela it was only conducted post-IRS implementation. The IRS was implemented as part of the routine malaria control programme in August 2017. Every fourth house from the village registration list was systematically selected, resulting in a sample of 300 households per village. A total of 3,075 individuals were enrolled for malaria testing using microscopy.

Results

After three to four months of application of IRS in August 2017, 59 malaria cases were confirmed, resulting in an overall prevalence of 1.9% (95% CI: 1.5-2.5). Of the positive cases, 18 cases (0.59%: 95% CI: 1.3-1.8) were from Shochora-Abela village, and 41 cases (1.33%: 95% CI: 1.1-1.3) were from Fango-Gelchecha. About age categories, the prevalence of malaria was 10.1% (95% CI: 5.9-15.9) among children under five, 4.7% (95% CI: 3.3-6.4) in children aged 5-14, and only 0.32% (95% CI: 0.13-0.67) in the age group 15 and above. Overall, P. falciparum was the dominant malaria parasite, accounting for 69.5% (95% CI: 56.1-80.8), while P. vivax malaria accounted for 30.5% (95% CI: 19.2-43.8). The malaria prevalence in Fango-Gelchecha village was 3.1% (95% CI: 2.3-4.0) before IRS and 2.6% (95% CI: 1.8-3.5) after IRS application. In the village of Shochora-Abela, the prevalence of malaria post-IRS was 1.2% (95% CI: 0.7-1.9), but the prevalence prior to IRS was not evaluated.

Conclusions

Plasmodium falciparum is the predominant parasite in the villages, mainly affecting children under five. Therefore, protecting young children should be the top priority for reducing infection burdens.

Determination of Plasmodium vivax and Plasmodium falciparum Malaria Exposure in Two Ethiopian Communities and Its Relationship to Duffy Expression

Despite historical dogma that Duffy blood group negativity of human erythrocytes confers resistance to Plasmodium vivax blood stage infection, cases of P. vivax malaria and asymptomatic blood stage infection (subclinical malaria) have recently been well documented in Duffy-negative individuals throughout Africa. However, the impact of Duffy negativity on the development of naturally acquired immunity to P. vivax remains poorly understood. We examined antibody reactivity to P. vivax and P. falciparum antigens at two field sites in Ethiopia and assessed Duffy gene expression by polymerase chain reaction amplification and sequencing of the GATA-1 transcription factor-binding site of the Duffy antigen receptor for chemokines (DARC) gene promotor region that is associated with silencing of erythroid cell transcription and absent protein expression. Antibodies to three of the four P. vivax blood stage antigens examined, RBP2b, EBP2, and DBPIISal-1, were significantly lower (P < 0.001) in Duffy-negative individuals relative to Duffy-positive individuals. In stark contrast, no clear pattern was found across Duffy-negative and Duffy-positive genotypes for P. falciparum antibodies. We conclude that lack of erythroid Duffy expression is associated with reduced serologic responses, indicative of less naturally acquired immunity and less cumulative exposure to blood stage P. vivax parasites relative to Duffy positive individuals living in the same communities.

Space-time modelling of monthly malaria incidence for seasonal associated drivers and early epidemic detection in Southern Ethiopia

BACKGROUND

Although Ethiopia has made great strides in recent years to reduce the threat of malaria, the disease remains a significant issue in most districts of the country. It constantly disappears in parts of the areas before reappearing in others with erratic transmission rates. Thus, developing a malaria epidemic early warning system is important to support the prevention and control of the incidence.

METHODS

Space-time malaria risk mapping is essential to monitor and evaluate priority zones, refocus intervention, and enable planning for future health targets. From August 2013 to May 2019, the researcher considered an aggregated count of genus Plasmodium falciparum from 149 districts in Southern Ethiopia. Afterwards, a malaria epidemic early warning system was developed using model-based geostatistics, which helped to chart the disease's spread and future management.

RESULTS

Risk factors like precipitation, temperature, humidity, and nighttime light are significantly associated with malaria with different rates across the districts. Districts in the southwest, including Selamago, Bero, and Hamer, had higher rates of malaria risk, whereas in the south and centre like Arbaminch and Hawassa had moderate rates. The distribution is inconsistent and varies across time and space with the seasons.

CONCLUSION

Despite the importance of spatial correlation in disease risk mapping, it may occasionally be a good idea to generate epidemic early warning independently in each district to get a quick picture of disease risk. A system like this is essential for spotting numerous inconsistencies in lower administrative levels early enough to take corrective action before outbreaks arise.

Plasmodium falciparum resistant to artemisinin and diagnostics have emerged in Ethiopia

Diagnosis and treatment of Plasmodium falciparum infections are required for effective malaria control and are pre-requisites for malaria elimination efforts; hence we need to monitor emergence, evolution and spread of drug- and diagnostics-resistant parasites. We deep sequenced key drug-resistance mutations and 1,832 SNPs in the parasite genomes of 609 malaria cases collected during a diagnostic-resistance surveillance study in Ethiopia. We found that 8.0% (95% CI 7.0-9.0) of malaria cases were caused by P. falciparum carrying the candidate artemisinin partial-resistance kelch13 (K13) 622I mutation, which was less common in diagnostic-resistant parasites mediated by histidine-rich proteins 2 and 3 (pfhrp2/3) deletions than in wild-type parasites (P = 0.03). Identity-by-descent analyses showed that K13 622I parasites were significantly more related to each other than to wild type (P < 0.001), consistent with recent expansion and spread of this mutation. Pfhrp2/3-deleted parasites were also highly related, with evidence of clonal transmissions at the district level. Of concern, 8.2% of K13 622I parasites also carried the pfhrp2/3 deletions. Close monitoring of the spread of combined drug- and diagnostic-resistant parasites is needed.

Malaria positivity rate trend analysis at water resources development project of Wonji Sugar Estate Oromia, Ethiopia

Evidence on the trends of the proportion of malaria infections detected by routine passive case detection at health facilities is important for public health decision making especially in areas moving towards elimination. The objective was to assess nine years of trends on clinical malaria infections detected at health facility and its associated climate factors, in the water resource development set up of Wonji sugar estate, Oromia, Ethiopia. Retrospective data were collected from malaria-suspected patient recording logbook at Wonji sugar factory's primary hospital. Monthly average meteorological data were obtained from the estate meteorological station. Data were collected from April through June 2018 and January 2022. The data were analyzed using Stata version 16.0 software for Chi-square and regression analysis. Over the last nine years, 34,388 cases were legible for analysis with complete data. Of these, 11.75% (4039/34388) were positive for clinical malaria. Plasmodium vivax test positivity was the highest proportion (8.2%, n = 2820) followed by Plasmodium falciparum (3.48%, n = 1197) and mixed infections (P. falciparum and P. vivax, 0.06%, n = 21). The odds of being positive for malaria was highest in males (AOR = 1.46; 95%CI = 1.36-1.52; P < 0.001) compared to females and in older individuals of above 15 years old (AOR = 4.55, 95%CI = 4.01-5.17, P < 0.001) followed by school-aged children (5-15 years old) (AOR = 2.16; 95%CI = 1.88-2.49, P < 0.001). There was no significant variation in the proportion of malaria-positive cases in the dry and wet seasons (P = 0.059). Malaria test positivity rates were associated with average monthly rainfall (AdjIRR = 1.00; 95%CI = 1.00-1.001, P < 0.001) while negatively associated with average monthly minim temperature (adjIRR = 0.94; 95%CI = 0.94-0.95; P < 0.001) and average monthly relative humidity (adjIRR = 0.99, 95%CI = 0.99-1.00, P = 0.023). There was year-round malaria transmission, adults especially males and school children frequently tested malaria positive. Hence, alternative vector management tools like larval source management have to be deployed besides ITNs and IRS in such water development areas to achieve the malaria elimination goal.

Climate change and malaria: some recent trends of malaria incidence rates and average annual temperature in selected sub-Saharan African countries from 2000 to 2018

BACKGROUND

Malaria is still a disease of massive burden in Africa, also influenced by climate change. The fluctuations and trends of the temperature and precipitation are well-known determinant factors influencing the disease's vectors and incidence rates. This study provides a concise account of malaria trends. It describes the association between average temperature and malaria incidence rates (IR) in nine sub-Saharan African countries: Nigeria, Ethiopia, South Africa, Kenya, Uganda, Ghana, Mozambique, Zambia and Zimbabwe. The incidence of malaria can vary both in areas where the disease is already present, and in regions where it is present in low numbers or absent. The increased vulnerability to the disease under increasing average temperatures and humidity is due to the new optimal level for vector breeding in areas where vector populations and transmission are low, and populations are sensitive due to low acquired immunity.

METHODS

A second source trend analysis was carried out of malaria cases and incidence rates (the number of new malaria cases per 1000 population at risk per year) with data from the World Health Organization (WHO) and average annual mean temperature from 2000 to 2018 from the World Bank's Climate Change Knowledge Portal (CCKP). Additionally, descriptive epidemiological methods were used to describe the development and trends in the selected countries. Furthermore, MS Excel was chosen for data analysis and visualization.

RESULTS

Findings obtained from this article align with the recent literature, highlighting a declining trend (20-80%) of malaria IR (incidence rate) from 2000 to 2018. However, malaria IR varies considerably, with high values in Uganda, Mozambique, Nigeria and Zambia, moderate values in Ghana, Zimbabwe, and Kenya, and low values in South Africa and Ethiopia in 2018. Evidence suggests varying IRs after average temperature fluctuations in several countries (e.g., Zimbabwe, Ethiopia). Also, an inverse temperature-IR relationship occurs, the sharp decrease of IR during 2012-2014 and 2000-2003, respectively, occurred with increasing average temperatures in Ghana and Nigeria. The decreasing trends and fluctuations, partly accompanying the temperature, should result from the intervention programmes and rainfall variability. The vulnerability and changing climate could arrest the recent trends of falling IR.

CONCLUSION

Thus, malaria is still a crucial public health issue in sub-Saharan Africa, although a robust decreasing IR occurred in most studied countries.

Burden and seasonal distribution of malaria in Ziquala district, Northeast Ethiopia: a 5-year multi-centre retrospective study

OBJECTIVE

This study was aimed to determine the 5-year trend of malaria positivity rate in Ziquala district, Northeast Ethiopia.

METHODS

Review of blood film reports from health institutions' laboratory record books using predesigned checklists was done as part of an institution-based retrospective study to assess the 5-year (2016/2017-2020/2021) trend of malaria. To display data and analyse patterns in the trend of malaria over the course of years, months and seasons, descriptive statistics were used. The results of the data analysis were displayed in tables and figures using SPSS V.26.0. P values under 0.05 were considered as statistically significant for all comparisons.

RESULTS

A total of 46 365 blood films from malaria suspected individuals were diagnosed using microscopy over the last 5 years. Of the diagnosed individuals, 14 429 (31.1%) were confirmed positive for Plasmodium infection. Plasmodium falciparum (59.7%) and Plasmodium vivax (37.0%) were the dominant species. The positivity rate of mixed infection (P. falciparum and P. vivax) was 3.3%. The maximum (3598; 29.6%) and minimum (2085; 29.1%) number of cases were reported in 2019/2020 and 2020/2021, respectively. Of the total cases, 9206 (63.8%) were in males. Moreover, the highest malaria positivity rate was observed in the age group of 15-45 (4040; 28.0%). Among the six health facilities, Ziquala district hospital had the highest malaria positivity rate (35.8%), followed by Tsitsika health centre (27.3%) and Mishra health centre (14.2%).

CONCLUSION

With P. falciparum being the most common species, malaria remains a severe public health threat in the district. Therefore, the district health office and other concerned bodies should strengthen and implement evidence-based malaria prevention and control measures.

Trend analysis of malaria in urban settings in Ethiopia from 2014 to 2019

BACKGROUND

Urbanization generally improves health outcomes of residents and is one of the potential factors that might contribute to reducing malaria transmission. However, the expansion of Anopheles stephensi, an urban malaria vector, poses a threat for malaria control and elimination efforts in Africa. In this paper, malaria trends in urban settings in Ethiopia from 2014 to 2019 are reported with a focus on towns and cities where An. stephensi surveys were conducted.

METHODS

A retrospective study was conducted to determine malaria trends in urban districts using passive surveillance data collected at health facilities from 2014 to 2019. Data from 25 towns surveyed for An. stephensi were used in malaria trend analysis. Robust linear models were used to identify outliers and impute missing and anomalous data. The seasonal Mann-Kendal test was used to test for monotonic increasing or decreasing trends.

RESULTS

A total of 9,468,970 malaria cases were reported between 2014 and 2019 through the Public Health Emergency Management (PHEM) system. Of these, 1.45 million (15.3%) cases were reported from urban settings. The incidence of malaria declined by 62% between 2014 and 2018. In 2019, the incidence increased to 15 per 1000 population from 11 to 1000 in 2018. Both confirmed (microscopy or RDT) Plasmodium falciparum (67%) and Plasmodium vivax (28%) were reported with a higher proportion of P. vivax infections in urban areas. In 2019, An. stephensi was detected in 17 towns where more than 19,804 malaria cases were reported, with most of the cases (56%) being P. falciparum. Trend analysis revealed that malaria cases increased in five towns in Afar and Somali administrative regions, decreased in nine towns, and had no obvious trend in the remaining three towns.

CONCLUSION

The contribution of malaria in urban settings is not negligible in Ethiopia. With the rapid expansion of An. stephensi in the country, the receptivity is likely to be higher for malaria. Although the evidence presented in this study does not demonstrate a direct linkage between An. stephensi detection and an increase in urban malaria throughout the country, An. stephensi might contribute to an increase in malaria unless control measures are implemented as soon as possible. Targeted surveillance and effective response are needed to assess the contribution of this vector to malaria transmission and curb potential outbreaks.

A Five-Year (2016-2020) Trend Analysis of Malaria Surveillance Data in Oromia Regional State, Ethiopia

Background

Continuous malaria surveillance data analysis plays a significant role in monitoring trends over time and evaluating the effectiveness of malaria prevention and control programs. Hence, this study was part of an effort to achieve this goal. This study's main aim was to analyse five years (2016-2020) of malaria surveillance data in the Oromia Region, Ethiopia.

Methods

A descriptive cross-sectional study design was used to analyse the five-year (2016-2020) trend of malaria cases in the Oromia Regional State, Ethiopia.

Results

A total of 5,843,373malaria suspected cases were reported during the five-year period. Among the total reported cases, 727,738 were a total of both clinical and parasitological confirmed cases. The average total malaria annual parasite incidence (API) was 4 per 1,000 persons. The highest malaria cases were observed during the spring and summer seasons. Conclusions and Recommendation. Trends of total clinical and confirmed malaria cases decreased from year to year except for the recent year with an exceptional variability in 2019. The highest or peak of malaria cases was observed during spring season (September-November). Malaria indicator-based performance plans and achievements should be regularly and strictly reviewed and evaluated at each level.

Infectivity of symptomatic Plasmodium vivax cases to different generations of wild-caught and laboratory-adapted Anopheles arabiensis using a membrane feeding assay, Ethiopia

When measuring human to mosquito transmission of Plasmodium spp., laboratory-adapted (colony) mosquitoes can be utilized. To connect transmission studies to the local epidemiology, it can be important to comprehend the relationship between infectivity in laboratory-adapted (colony) and wild-caught (wild) mosquitoes of the same species. Microscopically confirmed Plasmodium vivax cases were recruited from health facilities in Arba Minch town, and a nested polymerase chain reaction (nPCR) was used for subsequent confirmation. We performed paired membrane-feeding assays using colony An. arabiensis and three generations of wild origin An. arabiensis. Anopheles arabiensis aged 3-6 days were fed after being starved for 8-14 h. Microscopically, the oocyst development was evaluated at day 7 after feeding. Circumsporozoite proteins (CSPs) assay was carried out by enzyme-linked immunosorbent assay (ELISA). In 19 paired feeding experiments, the feeding efficiency was more than doubled in colony (median: 62.5%; interquartile range, IQR: 35-78%) than in wild mosquitoes (median: 28.5%; IQR: 17.5-40%; P < 0.001). Among the 19 P. vivax gametocyte-positive blood samples, 63.2% (n = 12) were infective to wild An. arabiensis and 73.7% (n = 14) were infective to colony An. arabiensis. The median infection rate was twice as high (26%) in the colony than in the wild (13%) An. arabiensis, although the difference was marginally insignificant (P = 0.06). Although the observed difference was not statistically significant (P = 0.19), the median number of oocysts per midgut was more than twice as high (17.8/midgut) in colony than in wild (7.2/midgut) An. arabiensis. The median feeding efficiency was 26.5% (IQR: 18-37%) in F1, 29.3% (IQR: 28-40%) in F2 and 31.2% (IQR: 30-37%) in F3 generations of wild An. arabiensis. Also, no significant difference was observed in oocyst infection rate and load between generations of wild An. arabiensis. CSP rate of P. vivax was 3.1% (3/97; 95% CI: 0.6-8.8%) in wild and 3.6% (3/84; 95% CI: 0.7-10.1%) in colony An. arabiensis. The results of the present study revealed that oocyst infection and load/midgut, and CSP rate were roughly comparable, indicating that colony mosquitoes can be employed for infectivity studies, while larger sample sizes may be necessary in future studies.

Effect of malaria prevention education on bed net utilization, incidence of malaria and treatment seeking among school-aged children in Southern Ethiopia; cluster randomized controlled trial

BACKGROUND

School-aged children (SAC) have an increased risk to contract malaria and play a major role in its transmission dynamics. However, their malaria prevention experience is poor. Thus, the effect of malaria prevention education (MPE) on bed net utilization, treatment seeking from a health facility and cumulative incidence of malaria was evaluated in Southern Ethiopia.

METHODS

A two arm cluster randomized controlled trial was conducted by recruiting 2038 SAC from 32 schools. Structured questionnaire was used to collect data on socio-demographic, economic, bed net ownership, bed net utilization, whether the participated child suffered from malaria and has got treatment from a health facility. Generalized mixed effect logistic regression using school as random variable was used to assess the effect of the intervention on the outcome variables.

RESULTS

The ownership of bed net in households of the control and intervention schools was similar respectively with 84.6 and 88.6% (Crude Odds Ratio (COR): 1.5; 95%CI: 0.5-4.8). The percentage of SAC slept under the bed net the night before the survey was also similar (55.1% versus 54.0%); COR:1.04; 95%CI: 0.5-2.4). Bed net utilization was affected by household size to the bed net ratio ≤ 2 (Adjusted Odds Ratio (AOR) = 1.6; 95%CI:1.3-2.1), bed net utilization at baseline of the study (AOR = 2.3; 95%CI:1.5-3.6), and history of malaria attack in the last twelve months (AOR = 1.3; 95%CI:1.01-1.8). Reported cumulative incidence of malaria and treatment seeking from a health facility by SAC was similar between intervention and control arms: -2.1% (COR = 0.8; 95%CI: 0.5-1.5) and 9.6% (COR = 1.4; 95%CI: 0.4-4.3) respectively. The reported incidence of malaria was affected by altitude (AOR = 0.5; 95%CI: 0.3-0.8), low and medium wealth index (AOR = 0.7; 95%CI: 0.5-0.96 and AOR = 0.7; 95%CI: 0.5-0.98), adequate bed net number for household members (AOR = 0.7; 95%CI:0.5-0.9) and bed net utilization (AOR = 1.3; 95%CI:1.1-1.8).

CONCLUSIONS

MPE had no significant effect on the use of malaria prevention measures considered, treatment seeking from a health facility and reported cumulative incidence of malaria though bed net use was associated with malaria incidence. Before organizing any health education program, sustainable implementation efforts have to be warranted especially in SAC, a neglected but relevant vulnerable and reservoirs.

TRIAL REGISTRATION

Pan African Clinical Trials Registry PACTR202001837195738, registered 21/01/2020.

Anopheles mosquito diversity, entomological indicators of malaria transmission and challenges of morphological identification in southwestern Ethiopia

BACKGROUND

A number of Anopheles species play either a primary or secondary role in malaria transmission. This necessitates understanding the species composition, bionomics, and behaviors of malaria mosquitoes in a particular geographic area, which is relevant to design and implement tailored intervention tools. This study aimed to assess the species composition, sporozoite infection rate, and blood meal origins of malaria mosquitoes in two malaria-endemic villages of Boreda district in Gamo Zone, southwest Ethiopia.

METHODS

Thirty houses, 20 for Center for Disease Control and Prevention (CDC) light traps and 10 for Pyrethrum Spray Catches (PSC) were randomly selected for bimonthly mosquito collection from October 2019 to February 2020. An enzyme-linked immunosorbent assay (ELISA) was carried out to detect the blood meal origins and circumsporozoite proteins (CSPs). The entomological inoculation rate (EIR) was calculated by multiplying the sporozoite and human biting rates from PSCs. Anopheles gambiae complex and An. funestus group samples were further identified to species by the polymerase chain reaction (PCR). Anopheles species with some morphological similarity with An. gambiae complex or An. funestus group were tested using the primers of the two species complexes.

RESULTS

A total of 14 Anopheles species were documented, of which An. demeilloni was found to be the dominant species. An. arabiensis was found to be positive for P. falciparum CSP with the overall CSP rate of 0.53% (1/190: 95% CI 0.01-2.9). The overall estimated P. falciparum EIR of An. arabiensis from PSC was 1.5 infectious bites/person/5 months. Of the 145 freshly fed Anopheles mosquitoes tested for blood meal sources, 57.9% (84/145) had bovine blood meal, 15.2% (22/145) had human blood meal origin alone, and 16.5% (24/145) had a mixed blood meal origin of human and bovine. Anopheles demeilloni were more likely to feed on blood meals of bovine origin (102/126 = 80.9%), while An. arabiensis were more likely to have blood meals of human origin. Eleven samples (2.6%; 11/420) were morphologically categorized as An. demeilloni, but it has been identified as An. leesoni (the only An. funestus group identified in the area) by PCR, though it requires additional verification by sequencing, because different species genes may have amplified for these species specific primers. Similarly, a small number of An. arabiensis were morphologically identified as An. salbaii, An. maculipalpis and An. fuscivenosus.

CONCLUSIONS AND RECOMMENDATIONS

In spite of the wide variety of Anopheles mosquito species, An. arabiensis dominates indoor malaria transmission, necessitating additional interventions targeting this species. In addition, increasing entomological knowledge may make morphological identification less difficult.

Clinical isolates of uncomplicated falciparum malaria from high and low malaria transmission areas show distinct pfcrt and pfmdr1 polymorphisms in western Ethiopia

BACKGROUND

Pfcrt gene has been associated with chloroquine resistance and the pfmdr1 gene can alter malaria parasite susceptibility to lumefantrine, mefloquine, and chloroquine. In the absence of chloroquine (CQ) and extensive use of artemether-lumefantrine (AL) from 2004 to 2020 to treat uncomplicated falciparum malaria, pfcrt haplotype, and pfmdr1 single nucleotide polymorphisms (SNPs) were determined in two sites of West Ethiopia with a gradient of malaria transmission.

METHODS

230 microscopically confirmed P. falciparum isolates were collected from Assosa (high transmission area) and Gida Ayana (low transmission area) sites, of which 225 of them tested positive by PCR. High-Resolution Melting Assay (HRM) was used to determine the prevalence of pfcrt haplotypes and pfmdr1 SNPs. Furthermore, the pfmdr1 gene copy number (CNV) was determined using real-time PCR. A P-value of less or equal to 0.05 was considered significant.

RESULTS

Of the 225 samples, 95.5%, 94.4%, 86.7%, 91.1%, and 94.2% were successfully genotyped with HRM for pfcrt haplotype, pfmdr1-86, pfmdr1-184, pfmdr1-1042 and pfmdr1-1246, respectively. The mutant pfcrt haplotypes were detected among 33.5% (52/155) and 80% (48/60) of isolates collected from the Assosa and Gida Ayana sites, respectively. Plasmodium falciparum with chloroquine-resistant haplotypes was more prevalent in the Gida Ayana area compared with the Assosa area (COR = 8.4, P = 0.00). Pfmdr1-N86Y wild type and 184F mutations were found in 79.8% (166/208) and 73.4% (146/199) samples, respectively. No single mutation was observed at the pfmdr1-1042 locus; however, 89.6% (190/212) of parasites in West Ethiopia carry the wild-type D1246Y variants. Eight pfmdr1 haplotypes at codons N86Y-Y184F-D1246Y were identified with the dominant NFD 61% (122/200). There was no difference in the distribution of pfmdr1 SNPs, haplotypes, and CNV between the two study sites (P > 0.05).

CONCLUSION

Plasmodium falciparum with the pfcrt wild-type haplotype was prevalent in high malaria transmission site than in low transmission area. The NFD haplotype was the predominant haplotype of the N86Y-Y184F-D1246Y. A continuous investigation is needed to closely monitor the changes in the pfmdr1 SNPs, which are associated with the selection of parasite populations by ACT.

Symptomatic and asymptomatic malaria prevalence and its determinant factors in pastoral communities of Waghemira Zone, Northeast Ethiopia: A community-based cross-sectional study

Background and Aims

Malaria elimination programs have also encountered numerous challenges, such as widespread asymptomatic carriers in endemic areas, which should be taken into account in malaria-control programs for effective transmission interruption. The purpose of this research was to determine the prevalence of symptomatic and asymptomatic malaria infections and associated factors, in pastoral communities.

Methods

A community-based cross-sectional study was conducted among selected districts in the Waghemra Zone, Northeast Ethiopia, from September to December 2022. A structured questionnaire was employed to collect sociodemographic data and associated risk factors. Plasmodium species were detected using light microscopy and a rapid diagnostic test. Data entry and analysis were carried out using SPSS version 26 software. The association between dependent and independent variables was explored by using multivariable logistic regression analyses. A statistically significant association was declared at a p-value of <0.05.

Results

The overall prevalence of malaria was 21.2% (134/633), with the predominant Plasmodium falciparum infections accounting for 67.8% (87/134). Among asymptomatic participants, 7.5% (34/451) and 10.2% (46/451) were diagnosed by rapid diagnostic test and light microscopy, respectively. On the other hand, the prevalence of symptomatic malaria was 44.5% (81/182) and 48.4% (88/182) as diagnosed by rapid diagnostic test and light microscopy, respectively. The presence of stagnant water near the houses, the utilization of insecticide-treated mosquito nets, the number of insecticide-treated mosquito nets, and outdoor stays at night were all positively linked with the prevalence of malaria.

Conclusions

The overall prevalence estimate for symptomatic and asymptomatic malaria was high. Malaria is still a public health problem in the study area. Malaria infection was associated with the presence of stagnant water near the houses, the utilization of insecticide-treated mosquito nets, the number of insecticide-treated mosquito nets, and outdoor stays at night. Improved access to all malaria interventions is needed to interrupt the transmission at the community level.

Analyzing Spatial and Temporal Patterns of Designated Malaria Risk Areas in Nepal from 2018 to 2021

Background: Nepal is preparing to eliminate malaria by 2026. To evaluate the progress of vector control and prioritize areas for targeted intervention, understanding the recent changing distribution of high and moderate malaria risk areas is vital. Methods: Patterns of designated high and moderate malaria risk wards in Nepal between 2018 and 2021 were analyzed to identify stable and newly generated high- and moderate-risk (HaMR) wards, using the Spatial Temporal Analysis of Moving Polygons (STAMP) method. Results and Conclusions: High-risk and moderate-risk wards decreased by about 55% and the number of districts containing these wards also decreased from 20 to 14. However, several stable and new HaMR wards, mostly in the northwest and the southwest of the country, are apparent, despite intervention efforts. Public health officials should prioritize those wards for malaria surveillance and vector control, and future studies should explore the underlying reasons for persistent risk wards.

Durability of long-lasting insecticidal nets (LLINs) in Ethiopia

BACKGROUND

The functional survival time of long-lasting insecticidal nets (LLINs), which varies across different field contexts, is critical for the successful prevention of malaria transmission. However, there is limited data on LLIN durability in field settings in Ethiopia.

METHODS

A three-year longitudinal study was conducted to monitor attrition, physical integrity, and bio-efficacy and residual chemical concentration of LLINs in four regions in Ethiopia. World Health Organization (WHO) guidelines were used to determine sample size, measure physical integrity, and calculate attrition rates, and functional survival time. Yearly bio-efficacy testing was done on randomly selected LLINs. An excel tool developed by vector works project was used to calculate the median functional survival time of the LLINs. Predictors of functional survival were identified by fitting binary and multivariate cox proportional hazards model.

RESULTS

A total of 3,396 LLINs were included in the analysis. A total of 3,396 LLINs were included in the analysis. By the end of 36 months, the proportion of LLINs functionally surviving was 12.9% [95% confidence interval (CI) 10.5, 15.6], the rates of attrition due to physical damage and repurposing were 48.8% [95% confidence interval (CI) 45.0, 52.6] and 13.8% [95% confidence interval (CI) 11.6, 14.6], respectively. The estimated median functional survival time was 19 months (95%CI 17, 21). Factors associated with shorter functional survival time include being in a low malaria transmission setting [Adjusted Hazards Ratio (AHR) (95%CI) 1.77 (1.22, 2.55)], rural locations [AHR (95%CI) 1.83 (1.17, 2.84)], and in a room where cooking occurs [AHR (95%CI) 1.28 (1.05, 1.55)]. Bioassay tests revealed that 95.3% (95%CI 86.4, 98.5) of the LLINs met the WHO criteria of bio-efficacy after 24 months of distribution.

CONCLUSION

The LLIN survival time was shorter than the expected three years due to high attrition rates and rapid loss of physical integrity. National malaria programmes may consider, procuring more durable LLINs, educating communities on how to prevent damage of LLINs, and revising the current three-year LLIN distribution schedule to ensure sufficient protection is provided by LLINs against malaria transmission. While this paper contributes to the understanding of determinants impacting functional survival, further research is needed to understand factors for the rapid attrition rates and loss of physical integrity of LLINs in field settings.

Cattle feeding tendency of Anopheles mosquitoes and their infection rates in Aradum village, North Wollo, Ethiopia: an implication for animal-based malaria control strategies

BACKGROUND

Surveillance of indoor and outdoor resting malaria vector populations is crucial to monitor possible changes in vector resting and feeding behaviours. This study was conducted to assess the resting behaviour, blood meal sources and circumsporozoite (CSP) rates of Anopheles mosquito in Aradum village, Northern Ethiopia.

METHODS

Mosquito collection was conducted from September 2019 to February 2020 using clay pots (indoor and outdoor), pit shelter and pyrethrum spray catches (PSC). The species of Anopheles gambiae complex and Anopheles funestus group were identified using polymerase chain reaction (PCR). Enzyme-linked immunosorbent assay (ELISA) was done to determine CSP and blood meal sources of malaria vectors.

RESULTS

A total of 775 female Anopheles mosquitoes were collected using the clay pot, PSC and pit shelter. Seven Anopheles mosquito species were identified morphologically, of which Anopheles demeilloni (593; 76.5%) was the dominant species followed by An. funestus group (73; 9.4%). Seventy-three An. funestus group screened by PCR, 91.8% (67/73) were identified as Anopheles leesoni and only 2.7% (2/73) were found to be Anopheles parensis. The molecular speciation of 71 An. gambiae complex confirmed 91.5% (65/71) of Anopheles arabiensis. The majority of Anopheles mosquitoes were collected from outdoor pit shelter (42.2%) followed by outdoor clay pots. The majority of the blood meal of An. demeilloni (57.5%; 161/280), An. funestus sensu lato 10 (43.5%) and An. gambiae (33.3%; 14/42) originated from bovine. None of the 364 Anopheles mosquitoes tested for Plasmodium falciparum and Plasmodium vivax sporozoite infections were positive.

CONCLUSION

Since the Anopheles mosquitoes in the area prefer to bite cattle, it may be best to target them with an animal-based intervention. Clay pots could be an alternative tool for outdoor monitoring of malaria vectors in areas where pit shelter construction is not possible.

International border malaria transmission in the Ethiopian district of Lare, Gambella region: implications for malaria spread into South Sudan

BACKGROUND

Despite notable progress in the control and prevention of malaria in the Horn of Africa, the disease continues to cause significant morbidity and mortality in various regions of Ethiopia, and elsewhere in the region. The transmission of malaria is affected by genetic, sociocultural, and ecological factors. Lare is an Ethiopian district adjacent to the Ethio-South Sudan border, in Gambella region. The region currently has the highest prevalence of malaria in Ethiopia. This study assesses the burden and spatiotemporal patterns of disease transmission, including the effect of climatic factors on the occurrence of malaria, across an international border crossing. This understanding can assist in crafting informed programmatic and policy decisions for interventions.

METHODS

This study was conducted in Lare district, Southwest Ethiopia, a temperate zone. A retrospective descriptive analysis was conducted using clinical service data collected between 2011 and 2021 from the 9 health facilities of the district. Both clinically diagnosed patients and those identified using microscopy and rapid diagnostic testing (RDT) were included in the study. Additionally, climate data was incorporated into analyses. Examples of analyses include malaria burden, positivity rate, incidence, species frequency, and an ANOVA to assess inter-annual case number and meteorological factor variation.

RESULTS

Between 2011 and 2021, a total of 96,616 suspected malaria cases were tested by microscopy or RDT, and 39,428 (40.8%) of these cases were reported as positive. There were 1276 patients admitted with 22 deaths recorded. There were further more significant fluctuations in positivity rates across years, the highest being 74.5% in 2021. Incidence varied from 18.0% in 2011 to 151.6% in 2016. The malaria parasite species most detected was Plasmodium falciparum, followed by a smaller proportion of Plasmodium vivax. The greatest proportions of P. falciparum cases were observed in 2018 and 2019, at 97.4% and 97.0% prevalence, respectively. There was significant seasonal variation in case number, the highest observed in July through September of each year. Climatic conditions of annual rainfall, temperature and humidity favored the increment of malaria cases from June until October.

CONCLUSION

The study shows that the burden, i.e. morbidity and mortality (with fluctuating patterns) of malaria are still significant public health problems and can pose serious consequences in the district. This has implication for cross-border malaria transmission risk due to considerable border crossings. The predominant cause of the disease is P. falciparum, which causes severe complications in patients. The district has to prepare to deal with such complications for better patient care and outcomes.

Malaria amongst children under five in sub-Saharan Africa: a scoping review of prevalence, risk factors and preventive interventions

INTRODUCTION

Africa has a higher burden of malaria-related cases and deaths globally. Children under five accounted for over two-thirds of all malaria deaths in sub-Saharan Africa (SSA). This scoping review aims to map evidence of the prevalence, contextual factors and health education interventions of malaria amongst children under 5 years (UN5) in SSA.

METHOD

Four main databases (PubMed, Central, Dimensions and JSTOR) produced 27,841 records of literature. Additional searches in Google, Google Scholar and institutional repositories produced 37 records. Finally, 255 full-text records were further screened, and 100 records were used for this review.

RESULTS

Low or no formal education, poverty or low income and rural areas are risk factors for malaria amongst UN5. Evidence on age and malnutrition as risk factors for malaria in UN5 is inconsistent and inconclusive. Furthermore, the poor housing system in SSA and the unavailability of electricity in rural areas and unclean water make UN5 more susceptible to malaria. Health education and promotion interventions have significantly reduced the malaria burden on UN5 in SSA.

CONCLUSION

Well-planned and resourced health education and promotion interventions that focus on prevention, testing and treatment of malaria could reduce malaria burden amongst UN5 in SSA.

Prevalence of asymptomatic malaria and associated factors among pregnant women at Boset District in East Shoa Zone, Oromia Region, Ethiopia: a cross-sectional study

BACKGROUND

Malaria infection during pregnancy is a significant public health problem that puts pregnant women at risk. Interruption of transmission of asymptomatic malaria among a population remained a challenge and the host serves as a reservoir for the malaria parasite; and is also recognized as a major barrier to malaria elimination. This study aimed to assess the prevalence of asymptomatic malaria and associated factors among pregnant women in the Boset District, East Shoa Zone, Oromia, Ethiopia.

METHODS

A community-based cross-sectional study was conducted to assess the prevalence of asymptomatic malaria and associated factors in pregnant women from February to March 2022. Using multistage sample techniques, 328 asymptomatic pregnant women were enrolled. Data were collected using a structured questionnaire. A rapid test and Giemsa-stained blood smear microscopy were used to diagnose Plasmodium infections. Epi info version 7 was used to code, enter, and clean data before being uploaded to SPSS version 25.0 for analysis. Bivariable and multivariable binary logistic regression were employed to find the associated factors. Variables in the multivariable model with a p-value < 0.05 were considered significantly associated with asymptomatic malaria.

RESULTS

Of the total 328 pregnant women who participated in this study, 9(2.74%) and 10(3.05%) were confirmed to be infected with Plasmodium species by microscopy and rapid diagnostic tests, respectively. Asymptomatic malaria during pregnancy was found to be significantly associated with not using an insecticide-treated bed net [(P = 0.002, AOR: 9.61; 95% CI (2.22-41.53)], lack of consultation and health education about malaria prevention during Antenatal care attendance [(P = 0.04, AOR: 4.05; 95% CI (1.02, 16.05)], and living close stagnant water [(P = 0.02, AOR: 4.43; 95% CI (1.17,16.82)].

CONCLUSIONS

The current study showed that asymptomatic malaria is prevalent in pregnant women. Not using insecticide-treated bed nets, inadequate health education during antenatal care, and living close to stagnant water are significantly associated with malaria infection. Thus, using insecticide-treated bed nets, health education, and avoiding stagnant water from residential areas could play significant roles in preventing asymptomatic malaria among pregnant women in the study area.