Malaria infection, disease and mortality among children and adults on the coast of Kenya

Investigating the dynamics of Plasmodium falciparum gametocyte carriage in expectant women under intermittent preventive treatment with sulfadoxine-pyrimethamine in Kilifi, study protocol

Introduction

Malaria in pregnancy remains a public health problem. The World Health Organization (WHO) recommends intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) to all pregnant women in moderate to high malaria transmission areas. Kenya's Ministry of Health recommends at least three doses of IPTp-SP (IPTp-SP3 +) to pregnant women in regions where malaria is endemic. Although SP remains cost-effective and effective for IPTp, there are two main challenges with the use of SP: i) widespread use of SP can lead to an increase in the prevalence of drug resistance molecular markers, including those encoding for Plasmodium falciparum dihydrofolate reductase ( dhfr) and P f dihydropteroate synthase ( dhps) and ii) SP, used either for curative or preventive treatment, is associated with microscopic and sub microscopic gametocytaemia, both of which contribute to sustained malaria transmission. Our study aims to investigate the dynamics of Plasmodium falciparum gametocyte carriage in pregnant women under intermittent preventive treatment with sulfadoxine-pyrimethamine in Kilifi.

Methods

This will be a cross-sectional study and will recruit (N=462) expectant women attending antenatal care (ANC) clinics in four health facilities within the Kilifi Health and Demographic Surveillance Sites: Njunju, Pingilikani, Ngerenya, and Kilifi County Teaching and Referral Hospital (KCTRH). To be recruited into our study, women will need to be in their first or second pregnancy when they are more likely to have malaria and should have had at least one dose of sulfadoxine-pyrimethamine.

Expected application of results

Our study will provide information on the current status of malaria during pregnancy in Kilifi and the prevalence of gametocytes among expectant mothers on IPT-SP. The results of this study may help inform new interventions to prevent malaria during pregnancy, including adding a third drug to SP with probable gametocytocidal effects.

Trends in malaria prevalence among school-age children in Mainland Tanzania, 2015-2023: A multilevel survey analysis

In high-transmission areas, school-aged children have higher malaria prevalence and contribute significantly to the transmission reservoir. Malaria infections can be asymptomatic or present with symptoms which may contribute to anaemia, severe illness and fatal malaria. This analysis provides trends of malaria prevalence and associated risk factors among school-aged children in mainland Tanzania. Data for this analysis were obtained from nationwide school malaria surveillance conducted every other year from 2015 to 2023. A total of 307,999 school children aged 5-16 years old from 850 public primary schools were tested for malaria infection using rapid diagnostic tests, assessed for malaria control intervention coverage and other malaria-related parameters. A multilevel mixed-effects logistic regression model was used to assess associated risk factors. Overall malaria prevalence was 21.6% (95%CI: 21.3-22.0) in 2015 which progressively decreased to 11.8% (95%CI: 11.5-12.0 p <0.001) in 2021 with no significant change in the overall malaria risk between 2021 and 2023 (AOR 1.32, CI: 0.92-1.81, p=0.08). School children aged between 9-12 years and 13-16 years had 20% higher risk of malaria (95% CI: 1.15-1.25) and 21% higher risk of malaria (95% CI: 1.16-1.27), respectively, compared to those aged between 5-8 years. Geographically, children from the Lake zone had the highest odds of prevalence (AOR: 18.75; 95% CI: 12.91-27.23) compared to the Central zone, and sleeping under an insecticide-treated net demonstrated a protective effect (AOR=0.68, 95%CI: 0.64-0.72, p < 0.001). There was a significant decline in the prevalence of malaria infection across the study period. We presented a countrywide active surveillance data, collected over time and in different settings which are unique and seldom presented. We believe various stakeholders will use our findings and join force to combat malaria not just in Tanzania but, in all malaria endemic countries.

Rethinking the evidence on COVID-19 in Africa

The COVID-19 pandemic was predicted to cause substantial mortality in Africa. However, some countries in Africa had a striking absence of overwhelmed hospitals and low reported mortality. The marked contrast with the overwhelmed hospitals and high mortality seen in Europe and other high-income settings was regarded as puzzling and a paradox. In this Review, we reflect on possible explanations for the paradox with particular reference to observations made on the ground in Kenya. The evidence is inconsistent with reduced viral transmission or poor surveillance as primary explanations for the discrepancy. Population age structure is an important but incomplete explanation of the epidemiology. Due to the high prevalence of asymptomatic infection, low mortality, and evidence of reduced inflammatory responses, we hypothesise that some populations in Africa might have reduced susceptibility to symptomatic COVID-19. The reduced inflammatory responses might result from immunoregulation or cross-reactive, pre-pandemic cellular immunity, although the evidence is not definitive. Local data are essential to develop public health policies that align with the reality on the ground rather than external perceptions.

Epidemiology, clinical spectrum, and outcomes of severe malaria in Eastern Uganda: a prospective study

BACKGROUND

In sub-Saharan Africa, malaria remains a public health problem despite some reports of declining incidence in the period 2000-2018. Since 2019, there have been some reports of disease epidemics and resurgences in areas that had registered steep declines and unusual clinical presentations. This study aimed to describe the epidemiology, clinical spectrum, and outcomes of severe malaria in children among malaria-endemic Eastern Uganda, a region that has recently experienced disease epidemics.

METHODS

This prospective study was conducted at Mbale Regional Referral Hospital, Uganda, from 08th May 2019 to August 15, 2023, as part of the Malaria Epidemiological, Pathophysiological and Intervention studies in Highly Endemic Eastern Uganda (EDCTP-TMA2016SF-1514-MEPIE Study). Children aged 60 days to 12 years who at admission tested positive for malaria and fulfilled the clinical World Health Organization criteria for surveillance of severe malaria were enrolled into the study following appropriate informed consent. Data were collected using a customized proforma on social demographic characteristics, clinical presentation, treatment, and outcomes. Laboratory analyses included complete blood counts, lactate, glucose, blood gases, electrolytes, metabolites, and coagulation markers. In addition, urinalysis using dipsticks was done. Data were analysed using STATA V15. The study had ethical and regulatory approval before data collection commenced.

RESULTS

A total of 1,379 participants were recruited. The median age was 4 years (2 months-12 years). Most children 757/1379 (54.9%) were under 5 years, and 825/1379 (59.8%) were males. The common symptoms were fever 1368 (99.2%), poor appetite 1095 (79.5%), inability to sit upright 1051 (76.2%), vomiting 944 (68.4%) and yellow eyes 833 (60.4%). The common signs included prostration, haemoglobinuria and jaundice. Prolonged hospitalization was found in 284/1339 (21.2%) and was associated with impaired consciousness 116/166 (30.1%), P = 0.003; haemoglobinuria 514/705 (27.1%), P < 0.001 and jaundice 505/690 (26.8%) P < 0.001. The overall mortality was 40/1347 (3.0%). Children who had > 1 severity feature were at a higher risk of mortality.

CONCLUSION

In this prospective study of children with severe malaria in Eastern Uganda, the overall mortality was 3.0% and the more the disease clinical syndromes the higher the risk of death.

Prevalence of malaria and associated factors among febrile children under 15 years at Bududa General Hospital, Eastern Uganda

BACKGROUND

A significant portion of malaria-related deaths occur in Africa, and Uganda is an endemic region where malaria remains a public health concern. This study aimed to determine the prevalence of malaria and its associated factors among febrile children under 15 years of age at Bududa General Hospital, Eastern Uganda.

METHODS

This cross-sectional study was conducted between April and June 2023. Informed consent was obtained from parents/guardians before 250 febrile children below 15 years were enrolled in this study. A structured questionnaire was administered to parents/guardians to collect sociodemographic characteristics and identify factors associated with malaria. Venous blood samples were collected from the children and screened for the presence of malaria parasitaemia using blood smear microscopy. The data collected were entered into an Excel spreadsheet and analysed using STATA version 14. Logistic regression models were used to determine the factors associated with malaria, and we considered ≤ 0.05 as the level of significance.

RESULTS

Out of the 250 study participants, the overall prevalence of malaria was 111(44.4%). Among the children who tested positive for malaria, 98 (88.3%) had Plasmodium falciparum, 11 (9.9%) had Plasmodium malariae, and (1.8%) had Plasmodium ovale infection. The mean parasite count was 21,951 parasites/µL of blood. The highest parasite count was 154,387 parasites/µL of blood, and the lowest count was 146 parasites/µL of blood. The prevalence rates of low, moderate, and high malaria parasitaemia were 46.8%, 28.0%, and 25.2%, respectively. In the multivariate analysis, the factors associated with malaria infections were older age; 1 to 5 years (p = 0.013), 6 to 10 years (p = 0.000), 11 to 15 years (p = 0.000), secondary education (p = 0.050), and no use of insecticide-treated bed nets (p = 0.002).

CONCLUSION

The prevalence of malaria among febrile children in this study was high, with nearly half of the participants showing severe infections. Health education on the correct use of insecticide-treated mosquito nets should be prioritized to help control malaria.

Malaria survey data and geospatial suitability mapping for understanding spatial and temporal variations of risk across Kenya

Malaria remains a public health concern in Kenya where children and pregnant women are vulnerable groups. The common interventions in place to fight malaria include using insecticide-treated bed nets (ITNs), knowledge and awareness about malaria, and intake of malaria anti-malaria drugs. Despite the availability of these interventions, Kenya still records more than 10,000 clinical cases annually. In this study, we examined how malaria and interventions varied across Kenya for 2015 and 2020. We analyzed the Kenya Malaria Indicator Survey (N = 10,072) for 2015 and, (N = 11,549) for 2020, and climate data with Fuzzy overlay method to examine how malaria and its interventions relate to environmental conditions required for malaria. The study found that 79 % of malaria cases were distributed in lake endemic, 11 % in coastal endemic, 7 % in highland epidemic, and 3 % in seasonal zone. Use of Insecticide-treated bed nets (ITNs) was 77 % in lake endemic, 13 % in coastal endemic, 9 % in highland epidemic, and 1 % in seasonal zone. Knowledge about malaria was 82 % in lake endemic, 9 % in highland epidemic, 6 % in coastal endemic, and 3 % in seasonal zone. Additionally, based on climate data, lake endemic zone was 94 % suitable for malaria transmission compared to other zones. Despite the use of ITNs and awareness about malaria, malaria transmission continues to be a threat especially in counties in the lake endemic zone. Furthermore, place of residence, climate factors, ownership of ITNs may be associated with malaria in the region.

Prevalence and Predictors of Adverse Birth Outcomes and Their Implications in Assessing the Safety of New Maternal Vaccines in Kenya

BACKGROUND

Successful introduction, high uptake and program effectiveness of new maternal vaccines aimed to prevent disease among infants require prior knowledge of their safety during pregnancy. We aimed to identify background adverse birth outcomes and their predictors in Kenya by which to aid future interpretation of outcomes for new maternal vaccination programs.

METHODS

A cross-sectional survey was conducted to assess birth outcomes from women residents within the health and demographic surveillance systems of Kilifi, Siaya and Nairobi, Kenya. All selected women had pregnancies registered in the years 2017-2020 through census rounds and had a birth outcome recorded by the time of data collection. They were traced at home for interviews and abstraction of birth outcome records from mother and child health booklets. Multivariable logistic regression was used to identify independent predictors of adverse birth outcomes.

RESULTS

A total of 2702 women were interviewed. Adverse birth outcomes occurred in 788/2702 (29.2%) of pregnancies: 433 (16.0%) were preterm (gestational age <37 weeks), 298 (11.0%) low birth weight (<2500 g), 99 (3.7%) macrosomic (>4000 g) and 41 (1.5%) stillbirths. Predictors of adverse birth outcomes were gestational diabetes [adjusted Odds Ratio (aOR): 3.32 (1.53-7.20)], malaria during pregnancy [aOR: 1.74 (1.23-2.48)], not attending antenatal care [aOR: 12.89 (2.17-76.68)] and home delivery [aOR: 1.58 (1.18-2.12)].

CONCLUSIONS

In 3 Kenyan settings, almost a third of pregnancies had adverse birth outcomes. Recognizing this baseline prevalence and the factors associated with adverse birth outcomes will be important in validating the safety of new maternal vaccines.

Cerebral Malaria in Adults: A Retrospective Descriptive Analysis of 80 Cases in a Tertiary Hospital in The Gambia, 2020-2023

Background and Aim

Cerebral malaria in Gambian children has been studied but there is limited information on CM in adults. The study assesses the clinical features and outcome of CM in adult patients admitted at the Edward Francis Small Teaching Hospital.

Method

This was a retrospective review of all adult patients with malaria admitted to the internal medicine department from October 18, 2020 to February 2, 2022.

Results

A total number of 319 adults were admitted with malaria. Eighty (25%) patients met the criteria for CM. The median age of the CM patients was 19 years. CM patients were younger (p < 0.001), more likely to be of the adolescent age group (p < 0.001), more likely to be referred from a lower-level health facility (p < 0.001), and more likely to be admitted in intensive care p < 0.001) as compared to NSCM or UM patients. The total in-hospital mortality of CM patients was 23.8%. Ten (52.6%) out of the 19 patients died within the first 24 h of admission. In multivariate analysis, CM patients with acute kidney injury at presentation was an independent predictor of mortality in this study.

Conclusion

CM seems to affect the adolescent age group more than the older adults in The Gambia. The clinicians should be able to identify these high-risk patient group and institute prompt critical care interventions and/or treatment. The findings in this study also identify the need to expand access of critical care interventions and hemodialysis to help improve the prognosis of adult CM patients in The Gambia.

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.

Risk factors for death among children with severe malaria, Ivukula sub-county, Namutumba district, Eastern Uganda, september 2021-february 2022

BACKGROUND

In February 2022, the Ministry of Health received reports of more than 100 child deaths from a 'strange disease' in Namutumba District over a period of 6 months from politicians through the media. Preliminary investigations by the district rapid response team confirmed the strange disease to be severe malaria. The scope of severe malaria deaths was investigated, associated factors identified, and recommendations made for control measures to inform early malaria treatment strategies in Namutumba District.

METHODS

A retrospective study was conducted in March 2022 in the most affected subcounty (Ivukula Subcounty) involving cases and controls. A case was defined as a death with a positive malaria test, fever and any of the following: convulsions, difficulty breathing, yellowing of eyes or palms, tea-coloured urine, anaemia (evidenced by pale eyes or palms, or clinically-identified in medical records), loss of consciousness, or reduced urine output (very little or no urine in a day) in a child ≤ 12 years from September 2021 to February 2022 in Ivukula Subcounty, Namutumba District. Controls were survivors with the same signs and symptoms, recruited in a 2:1 ratio with cases. Cases and controls were actively searched using a door-to-door approach with the help of community health workers. Caretakers were interviewed to obtain data on signs and symptoms, socio-demographic information, health-seeking behaviours and health system risk factors. Drugs and bloodstock status information was obtained from health workers using an interview guide. Factors associated with death were identified using multivariate logistic regression and thematic analysis for qualitative data.

RESULTS

Among 46 cases, 29 (63%) were < 5 years, and 23 (50%) were female. Death among children with severe malaria was significantly associated with treatment non-completion (aOR = 9.7, 95%CI 1.8-53) and inability to receive blood transfusion for anaemic patients (aOR = 7.1, (95%CI 1.4-36). Healthcare workers reported that inability to reach referral sites due to transport costs, stockouts of anti-malarials and blood products at health facilities, and absence of integrated community case management of childhood illnesses (iCCM) contributed to deaths among children with severe malaria.

CONCLUSION

Lack of access to anti-malarial treatment and to blood transfusions among anaemic patients due to stockouts were associated with severe malaria deaths among children ≤ 12 years in Ivukula Subcounty. Recommendations made were: accurate quantification of anti-malarials for health facilities, offering transport support to severe patients referred to higher-level facilities, and increasing access to blood products. Activation of iCCM could facilitate public health efforts against severe malaria in the district.

Current Status of Malaria Control and Elimination in Africa: Epidemiology, Diagnosis, Treatment, Progress and Challenges

The African continent carries the greatest malaria burden in the world. Falciparum malaria especially has long been the leading cause of death in Africa. Climate, economic factors, geographical location, human intervention and unstable security are factors influencing malaria transmission. Due to repeated infections and early interventions, the proportion of clinically atypical malaria or asymptomatic plasmodium carriers has increased significantly, which easily lead to misdiagnosis and missed diagnosis. African countries have made certain progress in malaria control and elimination, including rapid diagnosis of malaria, promotion of mosquito nets and insecticides, intermittent prophylactic treatment in high-risk groups, artemisinin based combination therapies, and the development of vaccines. Between 2000 and 2022, there has been a 40% decrease in malaria incidence and a 60% reduction in mortality rate in the WHO African Region. However, many challenges are emerging in the fight against malaria in Africa, such as climate change, poverty, substandard health services and coverage, increased outdoor transmission and the emergence of new vectors, and the growing threat of resistance to antimalarial drugs and insecticides. Joint prevention and treatment, identifying molecular determinants of resistance, new drug development, expanding seasonal malaria chemo-prevention intervention population, and promoting the vaccination of RTS, S/AS01 and R21/Matrix-M may help to solve the dilemma. China's experience in eliminating malaria is conducive to Africa's malaria prevention and control, and China-Africa cooperation needs to be constantly deepened and advanced. Our review aims to help the global public develop a comprehensive understanding of malaria in Africa, thereby contributing to malaria control and elimination.

Mature beyond their years: young children who escape detection of parasitemia despite living in settings of intense malaria transmission

Despite having the highest risk of progressing to severe disease due to lack of acquired immunity, the youngest children living in areas of highly intense malaria transmission have long been observed to be infected at lower rates than older children. Whether this observation is due to reduced exposure to infectious mosquito bites from behavioral and biological factors, maternally transferred immunity, genetic factors, or enhanced innate immunity in the young child has intrigued malaria researchers for over half a century. Recent evidence suggests that maternally transferred immunity may be limited to early infancy and that the young child's own immune system may contribute to control of malarial symptoms early in life and prior to the development of more effective adaptive immunity. Prospective studies of active and passive detection of Plasmodium falciparum blood-stage infections have identified young children (<5 years old) who remain uninfected through a defined surveillance period despite living in settings of highly intense malaria transmission. Yet, little is known about the potential immunological basis for this 'aparasitemic' phenotype. In this review, we summarize the observational evidence for this phenotype in field studies and examine potential reasons why these children escape detection of parasitemia, covering factors that are either extrinsic or intrinsic to their developing immune system. We discuss the challenges of distinguishing malaria protection from lack of malaria exposure in field studies. We also identify gaps in our knowledge regarding cellular immunity in the youngest age group and propose directions that researchers may take to address these gaps.

Diagnosis and management of malaria in the intensive care unit

Malaria is responsible for approximately three-quarters of a million deaths in humans globally each year. Most of the morbidity and mortality reported are from Sub-Saharan Africa and Asia, where the disease is endemic. In non-endemic areas, malaria is the most common cause of imported infection and is associated with significant mortality despite recent advancements and investments in elimination programs. Severe malaria often requires intensive care unit admission and can be complicated by cerebral malaria, respiratory distress, acute kidney injury, bleeding complications, and co-infection. Intensive care management includes prompt diagnosis and early initiation of effective antimalarial therapy, recognition of complications, and appropriate supportive care. However, the lack of diagnostic capacities due to limited advances in equipment, personnel, and infrastructure presents a challenge to the effective diagnosis and management of malaria. This article reviews the clinical classification, diagnosis, and management of malaria as relevant to critical care clinicians, highlighting the role of diagnostic capacity, treatment options, and supportive care.

Age-specific malaria vulnerability and transmission reservoir among children

Purpose

The pediatric population, especially under-five children, is highly susceptible to malaria and accounts for 76 % of global malaria deaths according to the World Malaria Report 2022. The purpose of this manuscript is to discuss the various factors involved in the susceptibility of the pediatric population to Malaria and the importance of this age group for malaria elimination.

Methodology

Data on pediatric malaria epidemiology that includes prevalence, risk factors, immune factors, socioeconomic factors, control methods, etc. were extracted from published literature using PubMed and Google Scholar. This data was further correlated with malaria incidence data from the World Health Organization (WHO) and the National Center for Vector Borne Diseases Control (NCVBDC).

Results

The younger age group is vulnerable to severe malaria due to an immature immune system. The risk of infection and clinical disease increases after the waning of maternal immunity. In the initial years of life, the developing brain is more susceptible to malaria infection and its after-effects. The pediatric population may act as a malaria transmission reservoir due to parasite density and asymptomatic infections. WHO recommended RTS,S/AS01 has limitations and may not be applicable in all settings to propel malaria elimination.

Conclusion

The diagnosis of malaria is based on clinical suspicion and confirmed with microscopy and/or rapid diagnostic testing. The school-age pediatric population serves as a transmission reservoir in the form of asymptomatic malaria since they have acquired some immunity due to exposure in early childhood. Targeting the hidden reservoir in the pediatric population and protecting this vulnerable group will be essential for malaria elimination from the countries targeting elimination.

Bayesian belief network modelling approach for predicting and ranking risk factors for malaria infections among children under 5 years in refugee settlements in Uganda

BACKGROUND

Malaria risk factors at household level are known to be complex, uncertain, stochastic, nonlinear, and multidimensional. The interplay among these factors, makes targeted interventions, and resource allocation for malaria control challenging. However, few studies have demonstrated malaria's transmission complexity, control, and integrated modelling, with no available evidence on Uganda's refugee settlements. Using the 2018-2019 Uganda's Malaria Indicator Survey (UMIS) data, an alternative Bayesian belief network (BBN) modelling approach was used to analyse, predict, rank and illustrate the conceptual reasoning, and complex causal relationships among the risk factors for malaria infections among children under-five in refugee settlements of Uganda.

METHODS

In the UMIS, household level information was obtained using standardized questionnaires, and a total of 675 children under 5 years were tested for malaria. From the dataset, a casefile containing malaria test results, demographic, social-economic and environmental information was created. The casefile was divided into a training (80%, n = 540) and testing (20%, n = 135) datasets. The training dataset was used to develop the BBN model following well established guidelines. The testing dataset was used to evaluate model performance.

RESULTS

Model accuracy was 91.11% with an area under the receiver-operating characteristic curve of 0.95. The model's spherical payoff was 0.91, with the logarithmic, and quadratic losses of 0.36, and 0.16 respectively, indicating a strong predictive, and classification ability of the model. The probability of refugee children testing positive, and negative for malaria was 48.1% and 51.9% respectively. The top ranked malaria risk factors based on the sensitivity analysis included: (1) age of child; (2) roof materials (i.e., thatch roofs); (3) wall materials (i.e., poles with mud and thatch walls); (4) whether children sleep under insecticide-treated nets; 5) type of toilet facility used (i.e., no toilet facility, and pit latrines with slabs); (6) walk time distance to water sources (between 0 and 10 min); (7) drinking water sources (i.e., open water sources, and piped water on premises).

CONCLUSION

Ranking, rather than the statistical significance of the malaria risk factors, is crucial as an approach to applied research, as it helps stakeholders determine how to allocate resources for targeted malaria interventions within the constraints of limited funding in the refugee settlements.

Evaluation of 4-Aminoquinoline Hydrazone Analogues as Potential Leads for Drug-Resistant Malaria

The emergence of resistance to first-line antimalarial drugs calls for the development of new therapies for drug-resistant malaria. The efficacy of quinoline-based antimalarial drugs has prompted the development of novel quinolines. A panel of 4-aminoquinoline hydrazone analogues were tested on the multidrug-resistant K1 strain of Plasmodium falciparum: IC50 values after a 48 h cycle ranged from 0.60 to 49 µM, while the 72 h cycle ranged from 0.026 to 0.219 μM. Time-course assays were carried out to define the activity of the lead compounds, which inhibited over 50% growth in 24 h and 90% growth in 72 h. Cytotoxicity assays with HepG2 cells showed IC50 values of 0.87-11.1 μM, whereas in MDBK cells, IC50 values ranged from 1.66 to 11.7 μM. High selectivity indices were observed for the lead compounds screened at 72 h on P. falciparum. Analyses of stage specificity revealed that the ring stages of the parasite life cycle were most affected. Based on antimalarial efficacy and in vitro safety profiles, lead compound 4-(2-benzylidenehydrazinyl)-6-methoxy-2-methylquinoline 2 was progressed to drug combination studies for the detection of synergism, with a combinatory index of 0.599 at IC90 for the combination with artemether, indicating a synergistic antimalarial activity. Compound 2 was screened on different strains of P. falciparum (3D7, Dd2), which maintained similar activity to K1, suggesting no cross-resistance between multidrug resistance and sensitive parasite strains. In vivo analysis with 2 showed the suppression of parasitaemia with P. yoelii NL (non-lethal)-treated mice (20 mg/kg and 5 mg/kg).

Malaria in adults after the start of Covid-19 pandemic: an analysis of admission trends, demographics, and outcomes in a tertiary hospital in the Gambia

BACKGROUND

Malaria remains a major public health concern in The Gambia. The study assessed the trend of malaria admissions and outcome of adult patients admitted after the start of the COVID-19 pandemic in a tertiary hospital in The Gambia.

METHODS

This was a retrospective hospital-based study and data was collected from the 18th October 2020 to 28th February 2023. Demographic data, clinical features, investigations, treatment, and outcomes were recorded.

RESULTS

A total of 499 malaria cases were admitted to the hospital over the 29 months of the study period. Data from 320 (67.2% of the total cases) adult patients admitted into the internal medicine department were analysed. The median age was 22 years, range (15-90) and 189 (59.1%) cases were youth with a youth (15-24 years) to older adult (> 24 years) ratio of 1.4:1. The majority of the patients were male 199 (62.2) with a male to female ratio of 1.6:1. The total number of malaria cases admitted into the internal medicine department increased from 103 cases in 2021 to 182 cases in 2022and admission peaked in November in both years. The total number of admitted malaria cases during the peak of the malaria season also increased from 92 patients between September 2021 and December 2021 to 132 patients from September 2022 to December 2022.There was also an increase in both severe and uncomplicated malaria during the same period. The total mortality was 31 (9.7%) and the rate was similar in 2021 9 (8.7%) and 2022 15 (8.4%). Patients with impaired consciousness were more likely to die when compared to those without impaired consciousness [19 (23.6%) vs 12 (5%), p  ≤ 0.001]. Patients with acute kidney injury were also more likely to die when compared with those without acute kidney injury [10 (20.4%) vs 15 (7.7%), p = 0.009].

CONCLUSION

The findings show an emerging and consistent trend of malaria admissions and the outcome in the youth and older adult population after the start of the COVID-19 pandemic in The Gambia. This, therefore, suggests the need for the implementation of targeted malaria prevention interventions in this population to further prevent the spread of the disease to the more vulnerable population.

Malaria diagnosis in rural healthcare facilities and treatment-seeking behavior in malaria endemic settings in western Kenya

Accurate malaria diagnosis and timely treatment are requirements for effective management of the disease. However, treatment efficacy may be significantly reduced in resource-constrained healthcare facilities with poorly equipped laboratories and frequent drug and rapid diagnostic test kit (RDT) stock-outs. Furthermore, patient may avoid seeking treatment from such facilities. The study's goal was to determine treatment-seeking behavior, malaria diagnosis and treatment quality, and likely treatment-seeking determinants in the local population. Passive case detection, which targeted all patients with suspected malaria cases, was conducted in ten public healthcare facilities over a three-month period. Monthly malaria cases, methods of diagnosis and antimalarial drug availability were assessed. A household-based survey was also carried out. Structured questionnaires were used to collect knowledge, attitude and practice (KAP) data from household heads. Malaria knowledge, treatment seeking behavior, and predictors of malaria treatment-seeking were all determined. Three of the seven dispensaries lacked a laboratory to conduct microscopy- diagnosis. These three dispensaries also experienced frequent RDT stock-outs, which resulted in depending on clinical signs as diagnosis for malaria. The majority of local residents with fever (50.3%) purchased antimalarial drugs from a chemist. About 37% of fever patients sought treatment at healthcare facility while the remaining 12.7% did not treat their fevers. In irrigated areas, 45.5% (46/64) of fever patients sought treatment at healthcare facilities, compared to 25% (18/64) in non-irrigated areas (p = 0.009). Most children aged below 5 who had fever (77.7%) were taken to healthcare facility for treatment compared to 31.4% of children aged 5-14 years or 20.9% of adults (0.0001). Predictors of treatment seeking included access to healthcare facility (OR = 16.23, 95% CI: 2.74-96.12), and ability to pay hospital bills (OR = 10.6, 95% CI: 1.97-57). Other factors that influenced health-seeking behavior included the severity of symptoms, the age of the patient and knowledge of malaria symptoms.

Determinants of malaria infections among children in refugee settlements in Uganda during 2018-2019

BACKGROUND

While 5% of 247 million global malaria cases are reported in Uganda, it is also a top refugee hosting country in Africa, with over 1.36 million refugees. Despite malaria being an emerging challenge for humanitarian response in refugee settlements, little is known about its risk factors. This study aimed to investigate the risk factors for malaria infections among children under 5 years of age in refugee settlements in Uganda.

METHODS

We utilized data from Uganda's Malaria Indicator Survey which was conducted between December 2018 and February 2019 at the peak of malaria season. In this national survey, household level information was obtained using standardized questionnaires and a total of 7787 children under 5 years of age were tested for malaria using mainly the rapid diagnostic test. We focused on 675 malaria tested children under five in refugee settlements located in Yumbe, Arua, Adjumani, Moyo, Lamwo, Kiryadongo, Kyegegwa, Kamwenge and Isingiro districts. The extracted variables included prevalence of malaria, demographic, social-economic and environmental information. Multivariable logistic regression was used to identify and define the malaria associated risk factors.

RESULTS

Overall, malaria prevalence in all refugee settlements across the nine hosting districts was 36.6%. Malaria infections were higher in refugee settlements located in Isingiro (98.7%), Kyegegwa (58.6%) and Arua (57.4%) districts. Several risk factors were significantly associated with acquisition of malaria including fetching water from open water sources [adjusted odds ratio (aOR) = 1.22, 95% CI: 0.08-0.59, P = 0.002], boreholes (aOR = 2.11, 95% CI: 0.91-4.89, P = 0.018) and water tanks (aOR = 4.47, 95% CI: 1.67-11.9, P = 0.002). Other factors included pit-latrines (aOR = 1.48, 95% CI: 1.03-2.13, P = 0.033), open defecation (aOR = 3.29, 95% CI: 1.54-7.05, P = 0.002), lack of insecticide treated bed nets (aOR = 1.15, 95% CI: 0.43-3.13, P = 0.003) and knowledge on the causes of malaria (aOR = 1.09, 95% CI: 0.79-1.51, P = 0.005).

CONCLUSIONS

The persistence of the malaria infections were mainly due to open water sources, poor hygiene, and lack of preventive measures that enhanced mosquito survival and infection. Malaria elimination in refugee settlements requires an integrated control approach that combines environmental management with other complementary measures like insecticide treated bed nets, indoor residual spraying and awareness.

A Study of Childhood Malaria trends at the University of Port Harcourt Teaching Hospital: 2006 - 2018

Background

Several efforts have been put in place to reduce the global burden of malaria especially in children and in sub-Saharan Africa. The study aimed to evaluate the impact of malaria control activities on the trend of childhood malarial diseases at a tertiary hospital in South-south Nigeria.

Methodology

A retrospective review of the case records of all malaria diagnoses including in-patient, out-patient, and emergency room, seen in the Department of paediatrics at the University of Port Harcourt Teaching Hospital from January 2006 to December 2018 was conducted.

Results

There were 41, 863 malaria cases diagnosed over the 12 years with a decline in yearly diagnosis and admissions, from the year 2006 through 2018. Total malaria admissions were 578, (44.5/ year), giving a severe malaria incidence of 1.26%, and there were 164 malaria death cases, with a yearly average of 12. The causes of death in the children with malarial parasitaemia were severe anaemia in 75 (45.7%), hypoglycaemia in 14 (8.5%), cerebral malaria in 17 (10.4%), and prostration with other co-morbidities, 22 (13.4%). Thirty-six children (22%) were convulsing and died soon after admission, with a compounding diagnosis of aspiration and respiratory failure.

Conclusion

There is a gradual reduction in childhood malaria disease, admission, and death, though this is slower than anticipated based on efforts and strategies put in place by the Nigerian government and various organizations.

Malaria among the elderly in five communities of Osun East district, Southwest Nigeria: Prevalence and association with non-communicable diseases

Objective:

The level of immunity against pathogens decreases with old age. As a result, the elderly may be regarded to be at increased risk of malaria morbidity and fatality. There is paucity of studies on malaria among the elderly population in Osun East district, Southwest Nigeria. This study aimed to determine the prevalence of malaria and its association with medical comorbidities among the elderly.

Methods:

A descriptive cross-sectional study was carried out, which involved 972 adult residents of five communities in Osun State, who were selected using a multistage random sampling technique. Data was collected with aid of a structured questionnaire. The medical history of respondents and anthropometric measures were obtained. The presence of malaria parasitaemia in the respondents was determined by rapid diagnostic test (RDT). Appropriate descriptive and inferential analyses were done.

Results:

Out of the 972 respondents, 504 (51.9%) were 60 years and above. The overall prevalence of malaria RDT positivity was 4%. The positivity rate was higher among the elderly (4.6%) compared to those less than 60 years (3.4%), albeit not statistically significant ( p = 0.36). Among these elderlies, 52.6% and 16.1% used insecticide-treated nets and insecticide sprays, respectively. There was no association between the prevalence of malaria positivity and comorbid conditions, such as hypertension ( p = 0.37), overweight/obesity ( p = 0.77), or diabetes ( p = 0.15). Malaria positivity rate was also not significantly associated with the use of insecticide-treated nets ( p = 0.64) or insecticide sprays ( p = 0.45).

Conclusion:

The malaria positivity rate was higher among the elderly in the study area, although not statistically significant. The prevalence was not associated with comorbid medical conditions.

Transcriptional Profiles Analysis of COVID-19 and Malaria Patients Reveals Potential Biomarkers in Children

The clinical presentation overlap between malaria and COVID-19 poses special challenges for rapid diagnosis in febrile children. In this study, we collected RNA-seq data of children with malaria and COVID-19 infection from the public databases as raw data in fastq format paired end files. A group of six, five and two biological replicates of malaria, COVID-19 and healthy donors respectively were used for the study. We conducted differential gene expression analysis to visualize differences in the expression profiles. Using edgeR, we explored particularly gene expression levels in different phenotype groups and found that 1084 genes and 2495 genes were differentially expressed in the malaria samples and COVID-19 samples respectively when compared to healthy controls. The highly expressed gene in the COVID-19 group we found CD151 gene which is facilitates in T cell proliferation, while in the malaria group, among the highly expressed gene we identified GBP5 gene which involved in inflammatory response and response to bacterium. By comparing both malaria and COVID-19 infections, the overlap of 62 differentially expressed genes patterns were identified. Among them, three genes (ENSG00000234998, H2AC19 and TXNDC5) were highly upregulated in both infections. Strikingly, we observed 13 genes such as HBQ1, HBM, SLC7A5, SERINC2, ATP6V0C, ST6GALNAC4, RAD23A, PNPLA2, GAS2L1, TMEM86B, SLC6A8, UBALD1, RNF187 were downregulated in children with malaria and uniquely upregulated in children with COVID-19, thus may be further validated as potential biomarkers to delineate COVID-19 from malaria-related febrile infection. The hemoglobin complexes and lipid metabolism biological pathways are highly expressed in both infections. Our study provided new insights for further investigation of the biological pattern in hosts with malaria and COVID-19 coinfection.

Low genetic diversity of Plasmodium falciparum merozoite surface protein 1 and 2 and multiplicity of infections in western Ethiopia following effective malaria interventions

BACKGROUND

Genetic diversity of malaria parasites can inform the intensity of transmission and poses a major threat to malaria control and elimination interventions. Characterization of the genetic diversity would provide essential information about the ongoing control efforts. This study aimed to explore allelic polymorphism of merozoite surface protein 1 (msp1) and merozoite surface protein 2 (msp2) to determine the genetic diversity and multiplicity of Plasmodium falciparum infections circulating in high and low transmission sites in western Ethiopia.

METHODS

Parasite genomic DNA was extracted from a total of 225 dried blood spots collected from confirmed uncomplicated P. falciparum malaria-infected patients in western Ethiopia. Of these, 72.4% (163/225) and 27.6% (62/225) of the samples were collected in high and low transmission areas, respectively. Polymorphic msp1 and msp2 genes were used to explore the genetic diversity and multiplicity of falciparum malaria infections. Genotyping of msp1 was successful in 86.5% (141/163) and 88.7% (55/62) samples collected from high and low transmission areas, respectively. Genotyping of msp2 was carried out among 85.3% (139/163) and 96.8% (60/62) of the samples collected in high and low transmission sites, respectively. Plasmodium falciparum msp1 and msp2 genes were amplified by nested PCR and the PCR products were analysed by QIAxcel ScreenGel Software. A P-value of less or equal to 0.05 was considered significant.

RESULTS

High prevalence of falciparum malaria was identified in children less than 15 years as compared with those  ≥ 15 years old (AOR = 2.438, P = 0.005). The three allelic families of msp1 (K1, MAD20, and RO33) and the two allelic families of msp2 (FC27 and 3D7), were observed in samples collected in high and low transmission areas. However, MAD 20 and FC 27 alleles were the predominant allelic families in both settings. Plasmodium falciparum isolates circulating in western Ethiopia had low genetic diversity and mean MOI. No difference in mean MOI between high transmission sites (mean MOI 1.104) compared with low transmission area (mean MOI 1.08) (p > 0.05). The expected heterozygosity of msp1 was slightly higher in isolates collected from high transmission sites (He = 0.17) than in those isolates from low transmission (He = 0.12). However, the heterozygosity of msp2 was not different in both settings (Pfmsp2: 0.04 in high transmission; pfmsp2: 0.03 in low transmission).

CONCLUSION

Plasmodium falciparum from clinical malaria cases in western Ethiopia has low genetic diversity and multiplicity of infection irrespective of the intensity of transmission at the site of sampling. These may be signaling the effectiveness of malaria control strategies in Ethiopia; although further studies are required to determine how specific intervention strategies and other parameters that drive the pattern.

Global malaria infection risk from climate change

As a long-standing public health issue, malaria still severely affects many parts of the world, especially Africa. With greenhouse gas emissions, temperatures continue to rise. Based on diverse shared socioeconomic pathways (SSPs), future temperatures can be estimated. However, the impacts of climate change on malaria infection rates in all epidemic regions are unknown. Here, we estimate the differences in global malaria infection rates predicted under different SSPs during several periods as well as malaria infection case changes (MICCs) resulting from those differences. Our results indicate that the global MICCs resulting from the conversion from SSP1-2.6 to SSP2-4.5, to SSP3-7.0, and to SSP5-8.5 are 6.506 (with a 95% uncertainty interval [UI] of 6.150-6.861) million, 3.655 (3.416-3.894) million, and 2.823 (2.635-3.012) million, respectively, from 2021 to 2040; these values represent increases of 2.699%, 1.517%, and 1.171%, respectively, compared to the 241 million infection cases reported in 2020. Temperatures increases will adversely affect malaria the most in Africa during the 2021-2040 period. From 2081 to 2100, the MICCs obtained for the three scenario shifts listed above are -79.109 (-83.626 to -74.591) million, -238.337 (-251.920 to -0.141) million, and -162.692 (-174.628 to -150.757) million, corresponding to increases of -32.825%, -98.895%, and -67.507%, respectively. Climate change will increase the danger and risks associated with malaria in the most vulnerable regions in the near term, thus aggravating the difficulty of eliminating malaria. Reducing GHG emissions is a potential pathway to protecting people from malaria.

Asymptomatic and submicroscopic Plasmodium infections in an area before and during integrated vector control in Homa Bay, western Kenya

BACKGROUND

Long-lasting insecticidal nets (LLINs) have been the primary vector control strategy until indoor residual spraying (IRS) was added in Homa Bay and Migori Counties in western Kenya. The objective of this study was to evaluate the impact of LLINs integrated with IRS on the prevalence of asymptomatic and submicroscopic Plasmodium infections in Homa Bay County.

METHODS

A two-stage cluster sampling procedure was employed to enroll study participants aged ≥ 6 months old. Four consecutive community cross-sectional surveys for Plasmodium infection were conducted in residents of Homa Bay county, Kenya. Prior to the start of the study, all study households received LLINs, which were distributed between June 2017 and March 2018. The first (February 2018) and second (June 2018) surveys were conducted before and after the first round of IRS (Feb-Mar 2018), while the third (February 2019) and fourth (June 2019) surveys were conducted before and after the second application of IRS (February-March 2019). Finger-prick blood samples were obtained to prepare thick and thin smears for microscopic determination and qPCR diagnosis of Plasmodium genus.

RESULTS

Plasmodium spp. infection prevalence by microscopy was 18.5% (113/610) before IRS, 14.2% (105/737) and 3.3% (24/720) after the first round of IRS and 1.3% (11/849) after the second round of IRS (p < 0.0001). Submicroscopic (blood smear negative, qPCR positive) parasitaemia reduced from 18.9% (115/610) before IRS to 5.4% (46/849) after IRS (p < 0.0001). However, the proportion of PCR positive infections that were submicroscopic increased from 50.4% (115/228) to 80.7% (46/57) over the study period (p < 0.0001). Similarly, while the absolute number and proportions of microscopy positives which were asymptomatic decreased from 12% (73/610) to 1.2% (9/849) (p < 0.0001), the relative proportion increased. Geometric mean density of P. falciparum parasitaemia decreased over the 2-year study period (p < 0.0001).

CONCLUSIONS

These data suggest that two annual rounds of IRS integrated with LLINs significantly reduced the prevalence of Plasmodium parasitaemia, while the proportion of asymptomatic and submicroscopic infections increased. To reduce cryptic P. falciparum transmission and improve malaria control, strategies aimed at reducing the number of asymptomatic and submicroscopic infections should be considered.

Clinical manifestations and outcomes of severe malaria in adult patients admitted to a tertiary hospital in the Gambia

BACKGROUND

Malaria is a major public health concern in The Gambia. There is limited data on the clinical manifestation and outcome of severe malaria in adult patients in The Gambia. The study therefore assessed the clinical manifestations and outcome of severe malaria in adult patients admitted at the Edward Francis Small Teaching Hospital.

METHODS

The study retrospectively reviewed the records of all malaria patients admitted from 18th October 2020 to 2nd February 2022. Demographic data, clinical features, investigations, treatment, and outcomes were recorded.

RESULTS

A total of 131 confirmed malaria patients were recruited into the study. The median age was 21 yrs, range (15-90) and most of them were within the youth age group (15-24yrs) 85 (64.9%). The majority of the patients were also male 88 (67.2%) with a male to female ratio of 2:1. The most common symptom at presentation was fever 119 (90.8%) and the most common sign was pallor 48 (36.6%). Seventy-six patients (58.1%) and 55 (41.9%) patients met the criteria for severe malaria and uncomplicated malaria diagnosis, respectively. The most common clinical feature amongst patients with severe malaria were impaired consciousness 34 (44.7%), severe anaemia 26 (34.2%) and acute kidney injury 20 (26.3%). Patients with severe malaria were younger with mean age of 22.9 vs. 29 yrs (p = 0.004), more likely to be referred from a lower-level health facility 62 (81.6%) vs. 34 (61.8%) (p = 0.012), to have a longer duration of admission (p = 0.024) and to die 13 (17.1%) vs. 0 (0%) (p = 0.001) as compared to patients with uncomplicated malaria. The total mortality was 13 (9.9%) and all the patients who died had severe malaria. Mortality was higher in patients with impaired consciousness 9 (26.5%) and there was a significant relationship between death and impaired consciousness 9 (69.3%) vs. 25 (21.4%) p = 0.001.

CONCLUSION

Severe malaria still affects young adults in an endemic area with significant mortality. This suggests the need for targeted malaria prevention, surveillance, case management and control strategies in this population group in The Gambia to help reduce morbidity and mortality of malaria.

Predicting new potential antimalarial compounds by using Zagreb topological indices

Molecular topology allows describing molecular structures following a two-dimensional approach by taking into account how the atoms are arranged internally through a connection matrix between the atoms that are part of a structure. Various molecular indices (unique for each molecule) can be determined, such as Zagreb, Balaban, and topological indices. These indices have been correlated with physical chemistry properties such as molecular weight, boiling point, and electron density. Furthermore, their relationship with a specific biological activity has been found in other reports. Therefore, its knowledge and interpretation could be critical in the rational design of new compounds, saving time and money in their development process. In this research, the molecular graph of antimalarials already in the pharmaceutical market, such as chloroquine, primaquine, quinine, and artemisinin, was calculated and used to compute the Zagreb indices; a relationship between these indices and the antimalarial activities was found. According to the results reported in this work, the smaller the Zagreb indices, the higher the antimalarial activity. This relationship works very well for other compounds series. Therefore, it seems to be a fundamental structural requirement for this activity. Three triazole-modified structures are proposed as possible potential antimalarials based on this hypothesis. Finally, this work shows that the Zagreb indices could be a cornerstone in designing and synthesizing new antimalarial compounds, albeit they must be proved experimentally.

Malaria hospitalisation in East Africa: age, phenotype and transmission intensity

BACKGROUND

Understanding the age patterns of disease is necessary to target interventions to maximise cost-effective impact. New malaria chemoprevention and vaccine initiatives target young children attending routine immunisation services. Here we explore the relationships between age and severity of malaria hospitalisation versus malaria transmission intensity.

METHODS

Clinical data from 21 surveillance hospitals in East Africa were reviewed. Malaria admissions aged 1 month to 14 years from discrete administrative areas since 2006 were identified. Each site-time period was matched to a model estimated community-based age-corrected parasite prevalence to provide predictions of prevalence in childhood (PfPR2-10). Admission with all-cause malaria, severe malaria anaemia (SMA), respiratory distress (RD) and cerebral malaria (CM) were analysed as means and predicted probabilities from Bayesian generalised mixed models.

RESULTS

52,684 malaria admissions aged 1 month to 14 years were described at 21 hospitals from 49 site-time locations where PfPR2-10 varied from < 1 to 48.7%. Twelve site-time periods were described as low transmission (PfPR2-10 < 5%), five low-moderate transmission (PfPR2-10 5-9%), 20 moderate transmission (PfPR2-10 10-29%) and 12 high transmission (PfPR2-10 ≥ 30%). The majority of malaria admissions were below 5 years of age (69-85%) and rare among children aged 10-14 years (0.7-5.4%) across all transmission settings. The mean age of all-cause malaria hospitalisation was 49.5 months (95% CI 45.1, 55.4) under low transmission compared with 34.1 months (95% CI 30.4, 38.3) at high transmission, with similar trends for each severe malaria phenotype. CM presented among older children at a mean of 48.7 months compared with 39.0 months and 33.7 months for SMA and RD, respectively. In moderate and high transmission settings, 34% and 42% of the children were aged between 2 and 23 months and so within the age range targeted by chemoprevention or vaccines.

CONCLUSIONS

Targeting chemoprevention or vaccination programmes to areas where community-based parasite prevalence is ≥10% is likely to match the age ranges covered by interventions (e.g. intermittent presumptive treatment in infancy to children aged 2-23 months and current vaccine age eligibility and duration of efficacy) and the age ranges of highest disease burden.

Controlled human malaria infection (CHMI) outcomes in Kenyan adults is associated with prior history of malaria exposure and anti-schizont antibody response

Background

Individuals living in endemic areas acquire immunity to malaria following repeated parasite exposure. We sought to assess the controlled human malaria infection (CHMI) model as a means of studying naturally acquired immunity in Kenyan adults with varying malaria exposure.

Methods

We analysed data from 142 Kenyan adults from three locations representing distinct areas of malaria endemicity (Ahero, Kilifi North and Kilifi South) enrolled in a CHMI study with Plasmodium falciparum sporozoites NF54 strain (Sanaria® PfSPZ Challenge). To identify the in vivo outcomes that most closely reflected naturally acquired immunity, parameters based on qPCR measurements were compared with anti-schizont antibody levels and residence as proxy markers of naturally acquired immunity.

Results

Time to endpoint correlated more closely with anti-schizont antibodies and location of residence than other parasite parameters such as growth rate or mean parasite density. Compared to observational field-based studies in children where 0.8% of the variability in malaria outcome was observed to be explained by anti-schizont antibodies, in the CHMI model the dichotomized anti-schizont antibodies explained 17% of the variability.

Conclusions

The CHMI model is highly effective in studying markers of naturally acquired immunity to malaria.

Trial registration Clinicaltrials.gov number NCT02739763. Registered 15 April 2016

Assessment of malaria infection among pregnant women and children below five years of age attending rural health facilities of Kenya: A cross-sectional survey in two counties of Kenya

Background

In Kenya, health service delivery and access to health care remains a challenge for vulnerable populations, particularly pregnant women and children below five years. The aim of this study, therefore, was to determine the positivity rate of Plasmodium falciparum parasites in pregnant women and children below five years of age seeking healthcare services at the rural health facilities of Kwale and Siaya counties as well as their access and uptake of malaria control integrated services, like antenatal care (ANC), offered in those facilities.

Methods

Cluster random sampling method was used to select pregnant women and children below five years receiving maternal and child health services using two cross-sectional surveys conducted in eleven rural health facilities in two malaria endemic counties in western and coastal regions of Kenya. Each consenting participant provided single blood sample for determining malaria parasitaemia using microscopy and polymerase chain reaction (PCR) techniques.

Results

Using PCR technique, the overall malaria positivity rate was 27.9% (95%CI: 20.9–37.2), and was 34.1% (95%CI: 27.1–42.9) and 22.0% (95%CI: 13.3–36.3) in children below five years and pregnant women respectively. Additionally, using microscopy, the overall positivity rate was 39.0% (95%CI: 29.5–51.6), and was 50.4% (95%CI: 39.4–64.5) and 30.6% (95%CI: 22.4–41.7) in children below five years and pregnant women respectively. Siaya County in western Kenya showed higher malaria positivity rates for both children (36.4% and 54.9%) and pregnant women (27.8% and 38.5%) using both PCR and microscopy diagnosis techniques respectively, compared to Kwale County that showed positivity rates of 27.2% and 37.9% for children and 5.2% and 8.6% for pregnant women similarly using both PCR and microscopy techniques respectively. Pregnant women presenting themselves for their first ANC visit were up to five times at risk of malaria infection, (adjusted odds ratio = 5.40, 95%CI: 0.96–30.50, p = 0.046).

Conclusion

Despite evidence of ANC attendance and administration of intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) dosage during these visits, malaria positivity rate was still high among pregnant women and children below five years in these two rural counties. These findings are important to the Kenyan National Malaria Control Programme and will help contribute to improvement of policies on integration of malaria control approaches in rural health facilities.

Malaria infection and severe disease risks in Africa

The relationship between community prevalence of Plasmodium falciparum and the burden of severe, life-threatening disease remains poorly defined. To examine the three most common severe malaria phenotypes from catchment populations across East Africa, we assembled a dataset of 6506 hospital admissions for malaria in children aged 3 months to 9 years from 2006 to 2020. Admissions were paired with data from community parasite infection surveys. A Bayesian procedure was used to calibrate uncertainties in exposure (parasite prevalence) and outcomes (severe malaria phenotypes). Each 25% increase in prevalence conferred a doubling of severe malaria admission rates. Severe malaria remains a burden predominantly among young children (3 to 59 months) across a wide range of community prevalence typical of East Africa. This study offers a quantitative framework for linking malaria parasite prevalence and severe disease outcomes in children.

Accuracy of verbal autopsy, clinical data and minimally invasive autopsy in the evaluation of malaria-specific mortality: an observational study

BACKGROUND

Global malaria mortality estimates are hindered by the low reliability of the verbal autopsy (VA) and the clinical records, the most common sources of information used to estimate malaria-specific mortality. We aimed to determine the accuracy of these tools, as well as of the minimally invasive autopsy (MIA), a needle-based postmortem sampling method, to identify malaria-specific mortality in a large series of deceased patients from Mozambique, using complete autopsy as the gold standard.

METHODS

Observational study that included 264 deaths, occurring at a tertiary level hospital in Mozambique, from 1 November 2013 to 31 March 2015 (17 months-long period). Clinical data were abstracted, a computer coded VA was completed using the clinical data as source of information, and an MIA followed by a complete autopsy were performed. Screening for malaria infection was conducted postmortem to all participants using molecular and histological techniques (PCR and immunohistochemistry).

FINDINGS

Malaria infection was considered the cause of death in 6/264 (2.3%) cases: 2/54 children (3.7%, both less than 5 years old) and 4/57 (7.0%) maternal deaths. The sensitivity and specificity of the VA, the clinical data and the MIA to identify malaria-specific deaths were 33.3% and 96.1%, 66.7% and 96.1%, and 100% and 100%, respectively. In addition, malaria was identified as a possible contributor in 14 additional patients who died of other diseases. These cases were also accurately identified by the MIA (sensitivity 82.4%, specificity 100%).

INTERPRETATION

The high sensitivity and specificity of the MIA in identifying malaria may help to improve current estimates of malaria-specific mortality in endemic areas.

Spatial-temporal clustering of malaria using routinely collected health facility data on the Kenyan Coast

BACKGROUND

The over-distributed pattern of malaria transmission has led to attempts to define malaria "hotspots" that could be targeted for purposes of malaria control in Africa. However, few studies have investigated the use of routine health facility data in the more stable, endemic areas of Africa as a low-cost strategy to identify hotspots. Here the objective was to explore the spatial and temporal dynamics of fever positive rapid diagnostic test (RDT) malaria cases routinely collected along the Kenyan Coast.

METHODS

Data on fever positive RDT cases between March 2018 and February 2019 were obtained from patients presenting to six out-patients health-facilities in a rural area of Kilifi County on the Kenyan Coast. To quantify spatial clustering, homestead level geocoded addresses were used as well as aggregated homesteads level data at enumeration zone. Data were sub-divided into quarterly intervals. Kulldorff's spatial scan statistics using Bernoulli probability model was used to detect hotspots of fever positive RDTs across all ages, where cases were febrile individuals with a positive test and controls were individuals with a negative test.

RESULTS

Across 12 months of surveillance, there were nine significant clusters that were identified using the spatial scan statistics among RDT positive fevers. These clusters included 52% of all fever positive RDT cases detected in 29% of the geocoded homesteads in the study area. When the resolution of the data was aggregated at enumeration zone (village) level the hotspots identified were located in the same areas. Only two of the nine hotspots were temporally stable accounting for 2.7% of the homesteads and included 10.8% of all fever positive RDT cases detected.

CONCLUSION

Taking together the temporal instability of spatial hotspots and the relatively modest fraction of the malaria cases that they account for; it would seem inadvisable to re-design the sub-county control strategies around targeting hotspots.

Relationship between blood Lead status and anemia in Ugandan children with malaria infection

BACKGROUND

In Uganda, childhood anemia remains a health challenge and is associated with malaria infection as well as iron deficiency. Iron deficiency is intertwined with nutritional status, age and other comorbidities including helminths and Lead toxicity. Environmental Lead levels accounts for one's blood Lead (BL) levels. Blood Lead competitively blocks iron absorption, inhibits hemoglobin (Hb) biosynthesis and elevates free erythrocyte protoporphyrin (FEP) levels. Lead toxicity's contribution towards anemia pathogenesis, especially during malaria infection has not been studied. Concomitant exposure to both malaria infection and Lead pollution, exacerbates the anemia status. This study therefore aimed at expounding the anemia status of these Ugandan children aged under 5years who are exposed to both malaria infection and environmental Lead pollution.

METHODS

Briefly, venous blood samples from 198 children were microscopically assayed for malaria parasite density (PD), and hemoglobin (Hb) concentrations using the cyanmethemoglobin method, while BL and FEP levels were determined by the standard atomic absorption spectrophotometric and fluorometric methods respectively.

RESULTS

One hundred and fifty-one (76.3%) of the children analyzed had moderate anemia (Hb <10>5 g/dL) with Means of BLL=8.6 µg/dL, Hb =7.5 g/dL, FEP/Hb =8.3 µg/g and PD =3.21×10³ parasites / µL, while eight (4%) were severely anemic (<5 g/dL). Regression analysis and statistical correlation between PD and Hb (r = -0.231, R²= 0.15 P-value < 0.001) was negative and weak as compared to that between FEP/Hb and Hb (r = -0.6, R²=0.572 P-value=0.001).

CONCLUSION

Based on the study's findings, we conclude that BL significantly contributes to the pathogenesis of anemia and therefore its co-existence with malaria infection in the host exacerbates the anemia status.

The relationship between facility-based malaria test positivity rate and community-based parasite prevalence

INTRODUCTION

Malaria surveillance is a key pillar in the control of malaria in Africa. The value of using routinely collected data from health facilities to define malaria risk at community levels remains poorly defined.

METHODS

Four cross-sectional parasite prevalence surveys were undertaken among residents at 36 enumeration zones in Kilifi county on the Kenyan coast and temporally and spatially matched to fever surveillance at 6 health facilities serving the same communities over 12 months. The age-structured functional form of the relationship between test positivity rate (TPR) and community-based parasite prevalence (PR) was explored through the development of regression models fitted by alternating the linear, exponential and polynomial terms for PR. The predictive ranges of TPR were explored for PR endemicity risk groups of control programmatic value using cut-offs of low (PR <5%) and high (PR ≥ 30%) transmission intensity.

RESULTS

Among 28,134 febrile patients encountered for malaria diagnostic testing in the health facilities, 12,143 (43.2%: 95% CI: 42.6%, 43.7%) were positive. The overall community PR was 9.9% (95% CI: 9.2%, 10.7%) among 6,479 participants tested for malaria. The polynomial model was the best fitting model for the data that described the algebraic relationship between TPR and PR. In this setting, a TPR of ≥ 49% in all age groups corresponded to an age-standardized PR of ≥ 30%, while a TPR of < 40% corresponded to an age-standardized PR of < 5%.

CONCLUSION

A non-linear relationship was observed between the relative change in TPR and changes in the PR, which is likely to have important implications for malaria surveillance programs, especially at the extremes of transmission. However, larger, more spatially diverse data series using routinely collected TPR data matched to community-based infection prevalence data are required to explore the more practical implications of using TPR as a replacement for community PR.