Burden of asymptomatic malaria among a tribal population in a forested village of central India: a hidden challenge for malaria control in India

Burden of Submicroscopic Plasmodium Infections and Detection of kelch13 Mutant Parasites in Military and Civilian Populations in Papua New Guinea

Malaria remains a major public health problem in Papua New Guinea (PNG) and an important force health protection issue for both PNG and Australian Defence Forces. To investigate the malaria burden in the military and civilians residing on military bases, a cross-sectional survey was conducted in April 2019 at three military bases in Wewak, Manus Island, and Vanimo, PNG. A total of 1,041 participants were enrolled; 235 military personnel from three bases and 806 civilians from Wewak and Vanimo. Polymerase chain reaction (PCR) revealed an overall high prevalence of Plasmodium infection in both the military and civilians. Among the military, the infection prevalence was significantly higher in Wewak (35.5%) and Vanimo (33.3%) bases than on Manus Island (11.8%). Among civilians, children (<16 years old) had significantly higher odds of being PCR positive than adults (≥16 years old). At Wewak and Vanimo, Plasmodium vivax accounted for 85.4%, 78.2%, and 66.2% of infections in military, children, and adult populations. Overall, 87.3%, 41.3%, and 61.3% of Plasmodium infections in the military, children, and adults, respectively, were detected only by PCR, not by microscopy (submicroscopic [SM] infections). Children had a significantly lower proportion of SM infections than adults and Papua New Guinea Defence Force personnel. Infection status was not associated with hemoglobin levels in these populations at the time of the survey. Mutant kelch13 (C580Y) parasites were identified in 5/68 Plasmodium falciparum-infected individuals. The survey results indicate extensive malaria transmission on these bases, especially in Wewak and Vanimo. More intensified interventions are required to reduce malaria transmission on PNG military bases.

Assessment of malaria risk in Southeast Asia: a systematic review

BACKGROUND

Several countries in Southeast Asia are nearing malaria elimination, yet eradication remains elusive. This is largely due to the challenge of focusing elimination efforts, an area where risk prediction can play an essential supporting role. Despite its importance, there is no standard numerical method to quantify the risk of malaria infection. Thus, there is a need for a consolidated view of existing definitions of risk and factors considered in assessing risk to analyse the merits of risk prediction models. This systematic review examines studies of the risk of malaria in Southeast Asia with regard to their suitability in addressing the challenges of malaria elimination in low transmission areas.

METHODS

A search of four electronic databases over 2010-2020 retrieved 1297 articles, of which 25 met the inclusion and exclusion criteria. In each study, examined factors included the definition of the risk and indicators of malaria transmission used, the environmental and climatic factors associated with the risk, the statistical models used, the spatial and temporal granularity, and how the relationship between environment, climate, and risk is quantified.

RESULTS

This review found variation in the definition of risk used, as well as the environmental and climatic factors in the reviewed articles. GLM was widely adopted as the analysis technique relating environmental and climatic factors to malaria risk. Most of the studies were carried out in either a cross-sectional design or case-control studies, and most utilized the odds ratio to report the relationship between exposure to risk and malaria prevalence.

CONCLUSIONS

Adopting a standardized definition of malaria risk would help in comparing and sharing results, as would a clear description of the definition and method of collection of the environmental and climatic variables used. Further issues that need to be more fully addressed include detection of asymptomatic cases and considerations of human mobility. Many of the findings of this study are applicable to other low-transmission settings and could serve as a guideline for further studies of malaria in other regions.

Assessing afebrile malaria and bed-net use in a high-burden region of India: Findings from multiple rounds of mass screening

A key obstacle in the fight against malaria is afebrile malaria. It remains undiagnosed and, therefore, is invisible to the health system. Apart from being a serious illness, it contributes to increased transmission. Existing studies in India have not adequately reported afebrile malaria and its determinants, including the use of long-lasting insecticide-treated nets (LLINs). This study used six waves of mass screening, which were conducted by the state government in the high-malaria-burden region of Chhattisgarh, a state in India, in 2020, 2021, and 2022. Each round of data collection included more than 15000 individuals. Descriptive statistics were used to analyse key indicators of malaria prevalence and LLIN use. Multivariate analyses were performed to identify the determinants of afebrile malaria and LLIN use. Malaria prevalence in the afebrile population varied from 0.6% to 1.4% across the different waves of mass screening. In comparison, malaria positivity among febrile individuals was greater than 33% in each wave. Afebrile malaria contributed to 19.6% to 47.2% of the overall malaria burden in the region. Indigenous communities (scheduled tribes) were more susceptible to malaria, including afebrile malaria. Individuals using LLINs were less likely to be affected by afebrile malaria. Overall, 77% of the individuals used LLINs in early monsoon season, and in winter the rate was lower at 55%. LLIN use was significantly associated with the number of LLINs the households received from the government. Although fever continues to be a primary symptom of malaria, afebrile malaria remains a significant contributor to the malaria burden in the region. The free distribution of LLINs should be expanded to include high-burden populations. Global policies must include strategies for surveillance and control of afebrile malaria in high-burden areas.

Prevalence and proportion estimate of asymptomatic Plasmodium infection in Asia: a systematic review and meta-analysis

Asymptomatic Plasmodium infection raises a problem for the persistent transmission of malaria in low-endemic areas such as Asia. This systematic review was undertaken to estimate the prevalence and proportion of asymptomatic Plasmodium infection in Asia. The systematic review was registered at PROSPERO (ID: CRD42022373664). The research followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. A comprehensive search of five databases, Ovid, Scopus, MEDLINE, PubMed, and Embase, was conducted to identify studies of asymptomatic Plasmodium infection in Asian countries. The pooled prevalence of asymptomatic Plasmodium infection, the pooled proportion of asymptomatic Plasmodium infection among all parasitised individuals, and the associated 95% confidence intervals were estimated using a random-effects model. A total of 916 articles were retrieved, and 87 articles that met the criteria were included in the systematic review. The pooled prevalence of asymptomatic Plasmodium infection among enrolled participants in Southeast Asia, South Asia, and Western Asia was 5.8%, 9.4%, and 8.4%, respectively. The pooled proportion of asymptomatic Plasmodium infection among all parasitised individuals in Southeast Asia, South Asia, and Western Asia was 89.3%, 87.2%, and 64.8%, respectively. There was a low prevalence of asymptomatic Plasmodium infection, but there was a high proportion of asymptomatic Plasmodium infection per all parasitised individuals in different parts of Asia. These results may support and facilitate elimination and control programs for asymptomatic Plasmodium infection in Asia.

Tribal Malaria in India: An Analysis of Malaria Incidence and Mortality over 20-Year Period (2000-2020)

Objective: Tribal malaria is well known for its substantial share in the overall malarial load of the country. This paper examines the levels and trends of malaria incidence and mortality in the tribal population for the past two decades. Methods: Data on malaria incidence and mortality were collected from an online e-repository that provides statistical data and information on 19 sectors, including health. Results: The analysis showed that the malaria incidence and mortality in tribal-dominated regions declined at an average annual rate of 4.3% per annum between 2000 and 2020, which accompanies the tremendous progress made in malaria control at the country level during this time period. The results also showed that between 2016 and 2020, the decline in tribal-dominated regions was consistent and noteworthy in terms of magnitude, a period that marks the implementation of the national framework for malaria elimination in the country. Conclusion: The decisive fall in the incidence and mortality of malaria in the tribal-dominated region has put India on track to achieve the target of 3.3 of the Sustainable Development Goals. However, with the pandemic impacting service delivery, monitoring, and reporting, including malaria control programs, it is important to maintain the momentum of progress in malaria control.

High asymptomatic malaria among seasonal migrant workers departing to home from malaria endemic areas in northwest Ethiopia

Background

In Ethiopia, thousands of seasonal migrant workers travel from non-malaria or mild malaria transmission areas to malaria-endemic areas for seasonal farm activities. Most of these migrants stay in the farm areas for land preparation, plowing, planting, weeding, and harvesting for a specific period and return to their living areas. However, there is limited evidence of how seasonal migrant workers contribute to the transmission of malaria to new or less malaria transmission areas.

Methods

A cross-sectional study was conducted at the departure phase of seasonal migrant workers in the Metema district from September 2018 to October 2019. A total of 1208 seasonal migrant workers were interviewed during their departure from farm sites to their homes. The face-to-face interviews were performed using a pretested structured questionnaire. Moreover, blood samples were collected from each study participant for microscopic malaria parasite examination. The data were fitted with the logistic regression model to estimate the predictors of malaria transmission.

Results

At departure to home, the prevalence of malaria among seasonal migrant workers was 17.5% (15.6–19.45%). Approximately 71.80% (177/212) of the cases were Plasmodium falciparum, and 28.20% (35/212) were Plasmodium vivax. Most seasonal migrant workers 934 (77.4%) were from rural residences and highlanders 660 (55%). Most 661 (55.4%) of the migrants visited two and more farm sites during their stay at development corridors for harvesting activities. Approximately 116 (54.7%) asymptomatic malaria cases returned to the Dembia 46 (21.7%), Chilaga 46 (19.8%) and Metema 28 (13.2%) districts.

Conclusion

In this study, asymptomatic malaria remains high among seasonal migrant workers departing to home from malaria endemic areas. This may fuel a resurgence of malaria transmission in the high lands and cause challenges to the country's malaria prevention and elimination efforts. Hence, tailored interventions for seasonal migrant workers could be in place to enhance malaria control and elimination in Ethiopia, such as asymptomatic malaria test and treat positive cases at departure and transit, and integration between malaria officers at their origin and departure for further follow-up to decrease any risk of spread at the origin.

The prevalence of symptomatic and asymptomatic malaria and its associated factors in Debre Elias district communities, Northwest Ethiopia

BACKGROUND

Malaria is a major cause of morbidity and mortality worldwide. According to the World Health Organization 2021 malaria report, it is considered to be endemic in 85 countries and territories. Malaria elimination programmes have also faced many challenges, such as widespread asymptomatic carriers in endemic regions, and they should be considered in malaria-control programmes in endemic areas for successful transmission interruption. This study aimed to assess the prevalence of symptomatic and asymptomatic malaria infections, and associated factors in Debre Elias district communities, Northwest Ethiopia from May to Jun 2018.

METHODS

A community-based cross-sectional study was conducted among selected kebeles in Debre Elias district, Amhara region, North-western Ethiopia. Multi-stage sampling technique was carried out to select representative households. A total of 440 randomly selected households were included, of which one individual per household was sampled for laboratory examination. Malaria prevalence was determined by light microscopy of stained blood films and using CareStart™ Malaria HRP2/pLDH (Pf/Pv) Combo rapid diagnostic test (RDT). A structured questionnaire was employed to collect socio-demographic data and associated risk factors. Data entry and analysis were carried out using Epi data 3.1 and SPSS version 23 software, respectively. The association between dependent and independent variables was explored by using bivariate and multivariate logistic regression analyses. Statistically significant association was declared at P-value of < 0.05.

RESULTS

A total of 440 (333 asymptomatic and 107 symptomatic) individuals were included in this study. The overall prevalence of malaria was 5% with the majority (59.1%) of infections caused by Plasmodium falciparum. Among asymptomatic participants, 4.8% (n = 16, 95% CI = 2.6-7.3) and 4.2% (n = 14, 95% CI = 2.1-6.5) were diagnosed and confirmed by RDT and light microscopy respectively. Similarly, the prevalence of malaria among 107 symptomatic individuals was 7.5% (n = 8, 95% CI = 2.8-12.6) by either RDT or light microscopy. Utilization of insecticide-treated net (ITN), availability of ITN, house with eave, previous history of malaria infection, and family history of malaria infection were significantly associated with malaria infection (P < 0.05).

CONCLUSION

In this study, the prevalence of asymptomatic and symptomatic malaria was moderate. Screening of both symptomatic and asymptomatic malaria in the community is very important to scale up intervention programmes.

The prevalence of tuberculosis and malaria in minority indigenous populations of South- East Asia and the Western Pacific Region: a systematic review and meta-analysis

Infectious diseases have been shown to disproportionately affect indigenous populations. Tuberculosis (TB) and malaria continue to impose a significant burden on humanity and are among the infectious diseases targeted within the 2030 Agenda for Sustainable Development. A systematic review and meta-analyses were undertaken to evaluate the prevalence of TB and malaria infections within minority indigenous populations of the South-East Asia and Western Pacific Regions. The review was undertaken in accordance with The Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines following a published protocol. A random effects meta-analysis was used to calculate the pooled prevalence of TB and malaria. A meta-regression analysis was applied to quantify associations with study covariates and a sub-group analysis undertaken where studies provided comparative data between minority indigenous and other population groups. From the 3,275 unique publications identified, 24 on TB, and 39 on malaria were included in the final analysis. The pooled prevalence of TB was 2.3% (95% CI: 1.7, 2.9) and the pooled prevalence of malaria was 19.9% (95% CI: 15.9, 24.2). There was significant (p = 0.000) heterogeneity (I2) between studies. Significant difference was not observed in TB and malaria prevalence between minority indigenous and other population groups, although the odds ratio of malaria infection in minority indigenous populations was 1.15 (95% CI 0.99, 1.34: p-value 0.06) compared to other population groups. The review identified a paucity of data on TB and malaria in minority indigenous populations despite the significant prevalence and burden of these diseases within these regions.

Asymptomatic Malaria in Households and Neighbors of Laboratory Confirmed Cases in Raya Kobo District, Northeast Ethiopia

Background

Malaria is the leading vector-borne parasitic disease that is causing high morbidity and mortality worldwide. So far huge efforts to control and eliminate malaria are hindered by the occurrence of asymptomatic carriers that are a potential source of infection. Yet, there is a scarcity of data nationally and in the current study area as well. Therefore, this study was aimed to assess the prevalence of asymptomatic malaria in Northeast Ethiopia.

Methods

A community-based cross-sectional study was conducted in 2019 involving a total of 270 study participants recruited via purposive non-probability sampling technique. A structured questionnaire was used to collect data on sociodemographic characteristics, individual and household factors related to asymptomatic malaria. Data were entered in Epi Data 3.1 version and analyzed by using SPSS version 20, and p< 0.05 was considered statistically significant.

Results

The overall prevalence of asymptomatic malaria was 7.0%, with 3.0%, 5.2%, and 12.0%, respectively by Rapid diagnostic tests (RDT), Microscopy and Polymerase chain reaction (PCR). The majority of infections (73.7%) were identified from index households. Previous malaria history (AOR: 4.030, 95% CI: 1.021-15.903), living with index cases (AOR: 3.880, 95% CI: 1.275-11.806) and family size > 6 members (AOR: 4.820, 95% CI: 1.260-18.437) were significant predictors of asymptomatic malaria.

Conclusion

Reactive case detection had identified considerably higher asymptomatic malaria cases in the community. Therefore, active case investigation should be established in the community by tracking the symptomatic cases at the health facilities.

Prevalence of Malaria and Associated Factors among Malaria-Suspected Patients Attending Hamusit Health Center, Northwest Ethiopia: A Cross-Sectional Study

Background

Malaria is one of the major public health problems in developing countries like Ethiopia. Despite efforts to reduce the mortality and morbidity, the disease is still a prominent health problem in Ethiopia. This study, therefore, was undertaken to assess the prevalence of malaria and associated factors among symptomatic patients in Northwest Ethiopia.

Methods

A facility based cross-sectional study was conducted from February to March 2020 among 210 febrile patients attending Hamusit Health Center, Northwest Ethiopia. A structured questionnaire was used to collect data on sociodemographic characteristics and factors perceived to be associated with Plasmodium infection. Questionnaire data was collected through face to face interview. Thin and thick blood films were prepared from capillary blood buffy coat samples. Data were analyzed using Statistical Package for Social Sciences Software version 20.

Results

Out of 210 malaria-suspected participants, 61 (29.0%) were confirmed to be infected by Plasmodium species. Plasmodium falciparum and P. vivax monoinfections were detected in 41 (19.5%) and 10 (4.8%) participants, respectively. Mixed infection was detected in 10 (4.8%) participants. Female participants (AOR = 2.261; 95% CI: 1.118-4.571; P = 0.023) and those having family members with history of malaria (AOR =2.261; 95% CI: 1.264-5.340; P = 0.009) had higher odds of acquiring Plasmodium infection as compared to their counterparts. Using insecticide-treated bed net and draining stagnant water were the most commonly mentioned malaria prevention measures reported by 71.9% and 8.1% of the respondents, respectively.

Conclusion

Malaria contributes significantly for febrile illnesses in the study area. Therefore, community mobilization should be strengthen in order to improve implementation of malaria control activities and, hence, reducing the prevalence.

Chloroquine and Sulfadoxine-Pyrimethamine Resistance in Sub-Saharan Africa-A Review

Malaria is a great concern for global health and accounts for a large amount of morbidity and mortality, particularly in Africa, with sub-Saharan Africa carrying the greatest burden of the disease. Malaria control tools such as insecticide-treated bed nets, indoor residual spraying, and antimalarial drugs have been relatively successful in reducing the burden of malaria; however, sub-Saharan African countries encounter great challenges, the greatest being antimalarial drug resistance. Chloroquine (CQ) was the first-line drug in the 20th century until it was replaced by sulfadoxine–pyrimethamine (SP) as a consequence of resistance. The extensive use of these antimalarials intensified the spread of resistance throughout sub-Saharan Africa, thus resulting in a loss of efficacy for the treatment of malaria. SP was replaced by artemisinin-based combination therapy (ACT) after the emergence of resistance toward SP; however, the use of ACTs is now threatened by the emergence of resistant parasites. The decreased selective pressure on CQ and SP allowed for the reintroduction of sensitivity toward those antimalarials in regions of sub-Saharan Africa where they were not the primary drug for treatment. Therefore, the emergence and spread of antimalarial drug resistance should be tracked to prevent further spread of the resistant parasites, and the re-emergence of sensitivity should be monitored to detect the possible reappearance of sensitivity in sub-Saharan Africa.

Diagnostic performance of an ultrasensitive HRP2-based malaria rapid diagnostic test kit used in surveys of afebrile people living in Southern Ghana

Background

The Alere™ Malaria Ag P.f Ultra-sensitive RDT (UsmRDT) kit is an HRP2-based malaria rapid diagnostic test (RDT) with enhanced sensitivity relative to the SD Bioline Malaria Ag P.f RDT (mRDT) kit. However, the diagnostic performance of the UsmRDT kit has not been evaluated in Ghana.

Methods

A total of 740 afebrile participants aged between 3 and 88 years old were recruited from the Central and Greater Accra Regions of Ghana during the off-peak malaria season. Axillary body temperature was measured, and a volume of 1 ml venous blood was drawn from each participant. Prior to separating the blood into plasma and packed cell pellets via centrifugation, the blood was spotted onto one UsmRDT and one mRDT kit and also used to prepare thick and thin blood smears as well as filter paper blood spots. Plasmodium falciparum specific polymerase chain reaction (PCR) was performed on gDNA extracted from 100 µl of the whole blood.

Results

The overall positivity rate for microscopy, PCR, UsmRDT and mRDT kit were 20.4%, 40.8%, 31.3% and 30.8%, respectively. Overall, the UsmRDT identified 9.3% (28/302) more PCR positive samples than the mRDT kits. All samples that were negative by the UsmRDT kit were also negative by the mRDT kit. Overall, the sensitivity and specificity of the UsmRDT was 73% (221/302) and 89% (388/436), respectively, while that for the mRDT kit was 58% and 90%, respectively.

Conclusion

Although the UsmRDT kit was not as sensitive as PCR at detecting asymptomatic P. falciparum carriage, it correctly identified P. falciparum in 9.3% of the study participants that were not captured by the mRDT kit. In malaria endemic settings, the UsmRDT would provide an added advantage by identifying more asymptomatic P. falciparum carriers than the mRDT kit for targeted treatment interventions.

Asymptomatic low-density Plasmodium infection during non-transmission season: a community-based cross-sectional study in two districts of North Eastern Region, India

BACKGROUND

Malaria elimination requires targeting asymptomatic and low-density Plasmodium infections that largely remain undetected. Therefore we conducted a cross-sectional study to estimate the burden of asymptomatic and low-density Plasmodium infection using conventional and molecular diagnostics.

METHODS

A total of 9118 participants, irrespective of age and sex, were screened for malaria using rapid diagnostic tests (RDTs), microscopy and polymerase chain reaction.

RESULTS

Among the participants, 707 presented with symptoms and 8411 without symptoms, of which Plasmodium was present in 15.6% (110/707) and 8.1% (681/8411), respectively. Low-density infection was found in 5.1% (145/2818) of participants and 8327 of 9118 were Plasmodium negative. Endemicity was propotional to asymptomatic infections (high endemicity 11.1% [404/3633] vs low endemicity 5.8% [277/4778]; odds ratio [OR] 2.0 [95% confidence interval {CI} 1.7 to 2.4]) but inversely related to low-density infection (high endemicity 3.7% [57/1545] vs low endemicity 6.9% [88/1273]; OR 1.9 [95% CI 1.4 to 2.7]). The spleen rate in children 2-9 y of age was 17.9% (602/3368) and the enlarged spleen index was 1.6. Children between 8 and 14 y showed higher odds for asymptomatic (adjusted OR [aOR] 1.75 [95% CI 1.4 to 2.2]) and low-density infections (aOR 0.63 [95% CI 0.4 to 1.0)] than adults.

CONCLUSIONS

The prevalence of asymptomatic and low-density Plasmodium infection undermines the usefulness of standard diagnostic tools used by health agencies. This necessitates deploying molecular tools in areas where malaria microscopy/RDTs indicate a dearth of infection.

Prevalence of Asymptomatic Malaria Parasitemia in Odisha, India: A Challenge to Malaria Elimination

The prevalence of malaria in India is decreasing, but it remains a major concern for public health administration. The role of submicroscopic malaria and asymptomatic malaria parasitemia and their persistence is being explored. A cross-sectional survey was conducted in the Kandhamal district of Odisha (India) during May-June 2017. Blood samples were collected from 1897 individuals for screening of asymptomatic parasitemia. Samples were screened using rapid diagnostic tests (RDTs) and examined microscopically for Plasmodium species. Approximately 30% of randomly selected samples (n = 586) were analyzed using real-time PCR (qPCR), and the genetic diversity of Plasmodium falciparum was analyzed. The prevalence of Plasmodium species among asymptomatic individuals detected using qPCR was 18%, which was significantly higher than that detected by microscopy examination (5.5%) or RDT (7.3%). Of these, 37% had submicroscopic malaria. The species-specific prevalence among asymptomatic malaria-positive cases for P. falciparum, Plasmodium vivax, and mixed infection (P. falciparum and P. vivax) by qPCR was 57%, 29%, and 14%, respectively. The multiplicity of infection was 1.6 and 1.2 for the merozoite surface protein-1 gene (msp1) and (msp2), respectively. Expected heterozygosity was 0.64 and 0.47 for msp1 and msp2, respectively. A significant proportion of the study population, 105/586 (18%), was found to be a reservoir for malaria infection, and identification of this group will help in the development of elimination strategies.

Prevalence and Risk Factors of Asymptomatic Plasmodium Infection in Gondar Zuria District, Northwest Ethiopia

Background

Malaria is one of the major public health problems worldwide. In Ethiopia, an increase in malaria incidence may be attributed to the presence of community-wide asymptomatic Plasmodium infection. This study aims to assess asymptomatic Plasmodium infection and associated factors in Gondar Zuria district, Northwest Ethiopia.

Methods

A community-based cross-sectional study was conducted in Gondar Zuria district from May to June 2019. Angacha and Hamsafeg villages were randomly selected from Tachtseda and Hamsafeg kebeles, respectively. Fifty-three (53) households were selected using systematic random sampling to recruit a total of 251 study participants. Sociodemographic data were collected using structured questionnaires. Thin and thick blood films were prepared and examined for evidence of parasites. Data were entered and analyzed using SPSS version 23. The association between dependent (asymptomatic Plasmodium infection) and independent (sex, age group, family size and previous history of malaria) variables was explored using bivariate and multivariate logistic regression. Statistically significant association was declared at a P-value of <0.05.

Results

A total of 251 individuals were tested, of whom 53.4% were females and 33.5% were above the age of 30 years. The prevalence of asymptomatic Plasmodium infection was 12%. The highest prevalence of malaria was observed in females (6.4%) and among the age group 15–29 years (4.4%). The majority (70%) of study participants had <500 parasites/μL of blood. A high parasitemia level (ie ≥1000 parasites/μL of blood) was observed in the age group 15–29 years. Age group, bed net usage and previous history of malaria were significantly associated with asymptomatic Plasmodium infection (P<0.05).

Conclusion

Asymptomatic Plasmodium infection remains an important public health problem in the study area. Further studies using more sensitive diagnostic methods are required to scale up the eradication and control program of malaria.

Demonstration of indigenous malaria elimination through Track-Test-Treat-Track (T4) strategy in a Malaria Elimination Demonstration Project in Mandla, Madhya Pradesh

BACKGROUND

Many malaria endemic countries are heading towards malaria elimination through the use of case management and vector control strategies, which employ surveillance, improving access to early diagnosis, prompt treatment., and integrated vector control measures. There is a consensus that elimination of malaria is feasible when rapid detection and prompt treatment is combined with mosquito-human contact interruption in an efficient and sustainable manner at community levels. This paper describes results of an integrated case management and vector control strategy for reducing malaria cases in 1233 villages over 3 years in district Mandla, Madhya Pradesh, India.

METHODS

The project enrolled the entire population (1,143,126) of Mandla district for fever surveillance followed by testing of febrile cases and treatment of positive subjects using T4 strategy, which is Track (by fever), Test (by RDTs), Treat (by ACT) and Track (for completion of treatment). In addition to the active and passive surveillance for detection and treatment of febrile cases, the project conducted mass screening and treatment to clear the asymptomatic reservoirs of infection. Febrile cases were also tested in the out-patient department of the District Hospital from June 2018 to September, 2018 and in a community-based medical camp from November 7 to 14, 2019. The project also used vector control measures for interrupting human-mosquito contact, and information, education and communication (IEC) campaigns to increase demand for malaria services at community level.

RESULTS

This project has revealed about 91% reduction of indigenous cases of malaria during the period from June 2017 to May 2020, through case management and vector control strategies. A total 357,143 febrile cases were screened, out of which 0.19% were found positive for the presence of malaria parasites, with Plasmodium falciparum and Plasmodium vivax ratio of 62:38. The prevalence of malaria was higher in individuals > 15 years of age (69% cases). The positivity rate was 0.33% in 2017-18, 0.13% in 2018-19, and 0.06% in 2019-20. In all of the 3 years of the project, the peak transmission correlated with rains. Mass screening revealed 0.18% positivity in Sep-Oct 2018, followed by 0.06% in June 2019, and 0.03% in December 2019, and these were mostly asymptomatic cases in the community. Imported cases into the district were mostly contributed by the distant state of Telangana (51.13%). Fever patients tested for malaria parasites in the District Hospital and medical camp revealed zero cases.

CONCLUSION

Using the current intervention and prevention tools along with optimum utilization of human resources, a 91% reduction in indigenous cases of malaria was seen in the district in 3 years. The reduction was similar in the three high prevalence blocks of the district. These results reveal that malaria elimination is achievable in India within a stipulated time frame. The reduction of malaria at the community level was further validated when zero malaria cases were diagnosed during hospital and community-based studies in Mandla. Prompt detection and treatment of imported/migratory cases may have prevented outbreaks in the district. This project has demonstrated that field programmes backed by adequate technical, management, operational, and financial controls with robust monitoring are needed for achieving malaria elimination.

Coverage of community case management for malaria through CHWs: a quantitative assessment using primary household surveys of high-burden areas in Chhattisgarh state of India

BACKGROUND

Community Case Management of Malaria (CCMM) has been implemented through community health workers (CHWs) in many countries. Existing studies have shown that CHWs can be viable means of implementing CCMM. However, not many studies have examined the coverage under large-scale CCMM programmes. India is a big contributor to global malaria burden. Chhattisgarh is a leading state in India in terms of malaria incidence and mortality. CCMM was implemented on a large scale through the 'mitanin' CHWs in rural Chhattisgarh from 2015. Under CCMM, 37,696 CHWs in 84 high-burden administrative blocks of the state were trained and equipped with rapid diagnostic tests (RDT), artemisinin-based combination therapy (ACT) and chloroquine.

METHODS

This descriptive quantitative study assesses coverage of CCMM in detection and treatment of Malaria over three rounds of household surveys-2015, 2016 and 2018. Household-interviews covered more than 15,000 individuals in each round, using multi-stage random sampling across the 84 blocks. The main objectives were to find out the coverage in identification and treatment of malaria and the share of CHWs in them. A 15-days recall was used to find out cases of fever and healthcare sought by them.

RESULTS

In 2018, 62% of febrile cases in rural population contacted CHWs. RDT, ACT and chloroquine were available with 96%, 80% and 95% of CHWs, respectively. From 2015 to 2018, the share of CHWs in testing of febrile cases increased from 34 to 70%, while it increased from 28 to 69% in treatment of malaria cases. CHWs performed better than other providers in treatment-completion and administered medication under direct observation to 72% of cases they treated.

CONCLUSION

This study adds to one of the most crucial but relatively less reported area of CCMM programmes, i.e. the extent of coverage of the total febrile population by CHWs, which subsequently determines the actual coverage of case-management in malaria. Mitanin-CHWs achieved high coverage and treatment-completion rates that were rarely reported in context of large-scale CCMM elsewhere. Close to community, well-trained CHWs with sufficient supplies of rapid tests and anti-malarial drugs can play a key role in achieving the desired coverage in malaria-management.

Diversity and Multiplicity of P. falciparum infections among asymptomatic school children in Mbita, Western Kenya

Multiplicity of infection (MOI) and genetic diversity of P. falciparum infections are important surrogate indicators for assessing malaria transmission intensity in different regions of endemicity. Determination of MOI and diversity of P. falciparum among asymptomatic carriers will enhance our understanding of parasite biology and transmission to mosquito vectors. This study examined the MOI and genetic diversity of P. falciparum parasite populations circulating in Mbita, a region characterized as one of the malaria hotspots in Kenya. The genetic diversity and multiplicity of P. falciparum infections in 95 asymptomatic school children (age 5–15 yrs.) residing in Mbita, western Kenya were assessed using 10 polymorphic microsatellite markers. An average of 79.69% (Range: 54.84–95.74%) of the isolates analysed in this study were polyclonal infections as detected in at least one locus. A high mean MOI of 3.39 (Range: 2.24–4.72) and expected heterozygosity (He) of 0.81 (Range: 0.57–0.95) was reported in the study population. The analysed samples were extensively polyclonal infections leading to circulation of highly genetically diverse parasite populations in the study area. These findings correlated with the expectations of high malaria transmission intensity despite scaling up malaria interventions in the area thereby indicating the need for a robust malaria interventions particularly against asymptomatic carriers in order to attain elimination in the region.

Prevalence of Asymptomatic Malaria among Children in the Tamale Metropolis: How Does the PfHRP2 CareStart™ RDT Perform against Microscopy?

Background

Asymptomatic carriage of the malaria parasites, likewise its misdiagnosis, especially false negatives, due to the use of substandard rapid diagnosis tests (RDTs) has been shown to hinder the progress of the fight against malaria.

Method

The study assessed the prevalence of asymptomatic malaria as well as the performance of Plasmodium falciparum-specific protein and histidine-rich protein 2 (PfHRP2) CareStart™ RDT against standard microscopy in the detection of malaria infection among 345 children (1–15 yrs) from two (2) basic schools in Tamale Metropolis.

Results

From the microscopy (considered as gold standard), prevalence of malaria among the asymptomatic children was found to be 2.6%, with sensitivity and specificity of CareStart™ RDT in detecting P. falciparum infections found to be 55.6% and 93.8%, respectively. The positive predictive value (PPV) and negative predictive value (NPV) of CareStart™ RDT were found to be 19.23% and 98.45%, respectively. There was an evidence showing a significant relation between CareStart™ RDT and microscopy in determining malaria infection (χ² = 30.579, p < 0.001).

Conclusion

Prevalence of asymptomatic malaria among children was found to be 2.6%. The study reported low sensitivity and PPV for PfHRP2 CareStart™ RDT in an asymptomatic population at instances of low parasitaemia.

Prevalence of afebrile malaria and development of risk-scores for gradation of villages: A study from a hot-spot in Odisha

Introduction

Malaria is a public health emergency in India and Odisha. The national malaria elimination programme aims to expedite early identification, treatment and follow-up of malaria cases in hot-spots through a robust health system, besides focusing on efficient vector control. This study, a result of mass screening conducted in a hot-spot in Odisha, aimed to assess prevalence, identify and estimate the risks and develop a management tool for malaria elimination.

Methods

Through a cross-sectional study and using WHO recommended Rapid Diagnostic Test (RDT), 13221 individuals were screened. Information about age, gender, education and health practices were collected along with blood sample (5 μl) for malaria testing. Altitude, forestation, availability of a village health worker and distance from secondary health center were captured using panel technique. A multi-level poisson regression model was used to analyze association between risk factors and prevalence of malaria, and to estimate risk scores.

Results

The prevalence of malaria was 5.8% and afebrile malaria accounted for 79 percent of all confirmed cases. Higher proportion of Pv infections were afebrile (81%). We found the prevalence to be 1.38 (1.1664–1.6457) times higher in villages where the Accredited Social Health Activist (ASHA) didn’t stay; the risk increased by 1.38 (1.0428–1.8272) and 1.92 (1.4428–2.5764) times in mid- and high-altitude tertiles. With regard to forest coverage, villages falling under mid- and highest-tertiles were 2.01 times (1.6194–2.5129) and 2.03 times (1.5477–2.6809), respectively, more likely affected by malaria. Similarly, villages of mid tertile and lowest tertile of education had 1.73 times (1.3392–2.2586) and 2.50 times (2.009–3.1244) higher prevalence of malaria.

Conclusion

Presence of ASHA worker in villages, altitude, forestation, and education emerged as principal predictors of malaria infection in the study area. An easy-to-use risk-scoring system for ranking villages based on these risk factors could facilitate resource prioritization for malaria elimination.

Risk factors for asymptomatic malaria infections from seasonal cross-sectional surveys along the China-Myanmar border

BACKGROUND

Border malaria, a shared phenomenon in the Greater Mekong Sub-region of Southeast Asia, is a major obstacle for regional malaria elimination. Along the China-Myanmar border, an additional problem arose as a result of the settlement of internally displaced people (IDP) in the border region. Since asymptomatic malaria significantly impacts transmission dynamics, assessment of the prevalence, dynamics and risk factors of asymptomatic malaria infections is necessary.

METHODS

Cross-sectional surveys were carried out in 3 seasons (March and April, July and November) and 2 sites (villages and IDP camps) in 2015. A total of 1680 finger-prick blood samples were collected and used for parasite detection by microscopy and nested RT-PCR (nRT-PCR). Logistic regression models were used to explore the risk factors associated with asymptomatic malaria at individual and household levels.

RESULTS

The prevalence of asymptomatic Plasmodium infections was 23.3% by nRT-PCR, significantly higher than that detected by microscopy (1.5%). The proportions of Plasmodium vivax, Plasmodium falciparum and mixed-species infections were 89.6, 8.1 and 2.3%, respectively. Asymptomatic infections showed obvious seasonality with higher prevalence in the rainy season. Logistic regression analysis identified males and school children (≤ 15 years) as the high-risk populations. Vector-based interventions, including bed net and indoor residual spray, were found to have significant impacts on asymptomatic Plasmodium infections, with non-users of these measures carrying much higher risks of infection. In addition, individuals living in poorly constructed households or farther away from clinics were more prone to asymptomatic infections.

CONCLUSIONS

Sub-microscopic Plasmodium infections were highly prevalent in the border human populations from IDP camps and surrounding villages. Both individual- and household-level risk factors were identified, which provides useful information for identifying the high-priority populations to implement targeted malaria control.