Malaria Endemic Areas Research Articles

Comparison of malaria diagnostic methods for detection of asymptomatic Plasmodium infections among pregnant women in northwest Ethiopia

BackgroundMalaria in pregnancy remains a major public health problem in the globe, especially in sub-Saharan Africa. In malaria endemic areas, most pregnant women remain asymptomatic, but malaria could still cause complications on the mother and her offspring; as well as serve as reservoirs to transmit infection. Despite these effects, no attention is given to the diagnosis of asymptomatic Plasmodium infections (APIs) using highly sensitive and specific laboratory diagnostic tools in Ethiopia. Therefore, the goal of this study was to compare the performance of Rapid Diagnostic Test (RDT), microscopy and real-time polymerase chain reaction (RT-PCR) to detect APIs among pregnant women.MethodsA health facility based cross -sectional study was conducted among pregnant women attending antenatal care at Fendeka town health facilities Jawi district, northwest Ethiopia from February to March, 2019. A total of 166 participants were enrolled by using convenient sampling technique. Socio-demographic features were collected using a semi structured questionnaire. Dried blood spot (DBS) samples were collected for molecular analysis. Asymptomatic Plasmodium infection on pregnant women was diagnosed using RDT, microscopy and RT-PCR. Descriptive statistics were used to determine the prevalence of APIs. Method comparison was performed, and Cohen’s kappa coefficient (k) was used to determine the degree of agreement among the diagnostic methods. Parasite densities were also calculated.ResultsThe prevalence of API was 9.6%, 11.4% and 18.7% using RDT, microscopy and RT-PCR, respectively. The overall proportion of API was 19.3%. Sensitivity of the RDT was 83.3% as compared with microscopy. Rapid Diagnostic Test and microscopy also showed sensitivity of 50% and 60%, respectively, as compared with RT-PCR. The mean parasite density was 3213 parasites/µl for P falciparum and 1140 parasites/µl of blood for P. vivax.ConclusionPrevalence of API in the study area was high. Both RDT and microscopy had lower sensitivity when compared with RT-PCR. Therefore, routine laboratory diagnosis of API among pregnant women should be given attention and done with better sensitive and specific laboratory diagnostic tools.

Exploring the Potential Relationship between Malaria Immunity and COVID-19 Protection

Although coronavirus disease 2019 (COVID-19) has led to significant morbidity and mortality worldwide, countries in the equatorial and tropical zones seem to have the lowest figures in terms of incidence and mortality. Throughout the pandemic, Africa has remained as lowest continent of accumulative cases and deaths. Since the African region is characterized by a high prevalence of malaria, the lowest number of cases of confirmed COVID-19 attracts scientists to look for possible links between the two diseases. Through this article, we reviewed existing literature concerning a possible explanation between low incidence and less severe COVID-19 in malaria-endemic areas. Different explanations were reviewed including malaria-COVID-19 cross-immunity, population structure, specific receptor’s role, and Vitamin D. The most important factor investigated was malaria immunity through previous exposure (s) which possibly explains these associations.

Immune responses associated with protection induced by chemoattenuated PfSPZ vaccine in malaria-naive Europeans.

Vaccination of malaria-naive volunteers with a high dose of Plasmodium falciparum sporozoites chemoattenuated by chloroquine (CQ) (PfSPZ-CVac [CQ]) has previously demonstrated full protection against controlled human malaria infection (CHMI). However, lower doses of PfSPZ-CVac [CQ] resulted in incomplete protection. This provides the opportunity to understand the immune mechanisms needed for better vaccine-induced protection by comparing individuals who were protected with those not protected. Using mass cytometry, we characterized immune cell composition and responses of malaria-naive European volunteers who received either lower doses of PfSPZ-CVac [CQ], resulting in 50% protection irrespective of the dose, or a placebo vaccination, with everyone becoming infected following CHMI. Clusters of CD4+ and γδ T cells associated with protection were identified, consistent with their known role in malaria immunity. Additionally, EMRA CD8+ T cells and CD56+CD8+ T cell clusters were associated with protection. In a cohort from a malaria-endemic area in Gabon, these CD8+ T cell clusters were also associated with parasitemia control in individuals with lifelong exposure to malaria. Upon stimulation with P. falciparum-infected erythrocytes, CD4+, γδ, and EMRA CD8+ T cells produced IFN-γ and/or TNF, indicating their ability to mediate responses that eliminate malaria parasites.

The relationship between anaemia and the use of treated bed nets among pregnant and non-pregnant women in Ghana.

Studies have indicated that the risk of malaria, particularly its association with anaemia in pregnant women, increases when treated bed nets are not used. This paper utilizes a statistical mechanical model to investigate whether there is a statistical relationship between the presence or absence of anaemia in pregnant and non-pregnant women and their decision to sleep under treated bed nets. Data from the Ghana Malaria Indicator Survey (GMIS), which includes both rural and urban malaria-endemic areas in Ghana, were employed in this study. A total of 2,434 women, comprising 215 pregnant and 2,219 non-pregnant participants, were involved. Among these, 4.76% of the pregnant and anaemic women and 45.89% of the non-pregnant and anaemic women slept under treated bed nets, while 0.86% of the pregnant and anaemic and 6.82% of the non-pregnant and anaemic women did not. The findings revealed that, in the absence of social interaction, non-anaemic pregnant women have a lower prevalence of choosing to use bed nets compared to their anaemic counterparts. Additionally, non-pregnant anaemic women showed a positive private incentive (30.87%) to use treated bed nets, implying a positive correlation between anaemia and the choice to sleep in a treated bed net. Furthermore, the study demonstrated that both pregnancy and anaemia status have a relationship with the use of treated bed nets in Ghana, especially when social interactions are considered. The interaction strength between non-pregnant and anaemic women interacting with each other shows a negative estimate (-1.49%), implying that there is no rewarding effect from imitation. These insights are crucial for malaria prevention and control programs, emphasizing the need for targeted interventions to enhance the use of treated bed nets among both pregnant and non-pregnant women in Ghana's malaria-endemic regions.

Detection of drug-resistant malaria in resource-limited settings: efficient and high-throughput surveillance of artemisinin and partner drug resistance.

Artemisinin-resistant Plasmodium falciparum malaria is currently spreading globally, including in Africa. Artemisinin resistance also leads to resistance to partner drugs used in artemisinin-based combination therapies. Sequencing of kelch13, which is associated with artemisinin resistance, culture-based partner drug susceptibility tests, and ELISA-based growth measurement are conventionally used to monitor resistance; however, their application is challenging in resource-limited settings. An experimental package for field studies with minimum human/material requirements was developed. First, qPCR-based SNP assay was applied in artemisinin resistance screening, which can detect mutations within 1 h and facilitate sample selection for subsequent processes. It had 100% sensitivity and specificity compared with DNA sequencing in the detection of the two common artemisinin resistance mutations in Uganda, C469Y and A675V. Moreover, in the partner drug susceptibility test, the cultured samples were dry-preserved on a 96-well filter paper plate and shipped to the central laboratory. Parasite growth was measured by ELISA using redissolved samples. It well reproduced the results of direct ELISA, reducing significant workload in the field (Pearson correlation coefficient: 0.984; 95% CI: 0.975-0.990). Large-scale and sustainable monitoring is required urgently to track rapidly spreading drug-resistant malaria. In malaria-endemic areas, where research resources are often limited, simplicity and feasibility of the procedure is especially important. Our approach combines a qPCR-based rapid test, which is also applicable to point-of-care diagnosis of artemisinin resistance and centralized analysis of ex vivo culture. The approach could improve efficiency of field experiments and accelerate global drug resistance surveillance.

Exploring a Moderation Analysis in the Interactive Relationship between the Determinants of ITN use in Ghana. A Multi-Level Analysis Based on the DHS 2019 Malaria Indicator Survey

Background: Insecticide-treated mosquito net (ITN) use is considered a highly efficient vector-control strategy for reducing malaria transmission and while this tool is widely available in vast malaria-endemic areas, there is still a gap in determining its effective use given household access and ownership. Malaria analysis posits that although the availability of ITNs in a household is a prerequisite for use, it does not determine its effective use. Rather, the determinants of ITN use are a result of the complex interplay of factors at the various socioecological levels (i.e., the individual, household, community, and net levels). These complexities are context-specific and shape the behavioral choices of ITN users. This study explores the context-specific factors associated with ITN use and focuses on the interactive relationships among the individual determinants of ITN use. A conceptual approach is developed to test the interactive effect of ITNs in the household on the relationship between the number of children under five years and ITN use by household members in Ghana. Method: Survey data with a sample size of 10,997 were drawn from the Ghana 2019 Demographic and Health Survey and the 2020 Malaria Indicator Survey to analyse the interactive relationship among individual, household, community, and net level variables. The relationship between these variables was assessed in a multivariate setting via a linear regression model. A further analysis involved a moderation effect of the number of ITNs on the relationship between the number of children under five years and household members´ ITN use using a single moderation model. Results: From the data analyses, the number of children under five years was positively associated with household members' ITN use (OR = 0.29, p < .001), and the number of ITNs was negatively associated with ITN use (OR = -06, p < .05) and was positively associated with the number of children under five years (OR = .23, p < .05). Gender was positively associated with ITN use and the number of children under five years and negatively associated with the number of ITNs. Increasing age was associated with decreased ITN use, number of children, and number of ITNs respectively. An increasing wealth index was associated with decreased ITN use, the number of children under five years, and the number of ITNs. The region was not significant with ITN use but associated with the number of children under five years. Place of residence was associated with ITN use, number of children under five years, and number of ITNs. A moderation effect of the number of ITNs (OR = -.05, p < .001) on the relationship between the number of children under five years and household members' ITN use was reported. Conclusion: The number of children under five years influenced household members´ ITN use but this relationship was moderated by the number of ITNs in the household. The proportion of the number of children under five years was moderately different for a high and low household ITN availability whereby ITN use decreased with higher ITN ownership and increased with lower ownership. Future research should focus on more moderation analysis to better understand the complexity of interactions between individual, household, community, and net-level factors that determine ITN use. This might help to better understand and engage better-targeted action in increasing effective ITN use in households relevant to their needs.

The discovery of human Plasmodium among domestic animals in West Sumba and Fakfak, Indonesia

Background In Indonesia, malaria incidence is at a high rate despite maximum preventive efforts. Therefore, this study aims to determine the possibility of a Plasmodium reservoir among domestic animals in malaria-endemic areas. Methods Animal blood was collected using EDTA tubes, then smeared and stained with Giemsa for Plasmodium microscopic identification. About 10 μl of blood was dropped on to a filter paper to capture Plasmodium DNA. Nested PCR was used for parasite molecular detection, while Plasmodium species were identified using the sequenced DNA. Results A total of 208 and 62 animal blood samples were collected from Gaura village, West Sumba and Fakfak village, West Papua, Indonesia respectively. In total, 32 samples from Gaura contained P. falciparum or P. vivax, while the Plasmodium percentage in buffalo, horse, goat, and dogs were 20.7%, 14.3%, 5.8%, 16.7%, respectively. P. knowlesi was not found in any of the samples, and no other species were detected in 18 pig blood samples. Conclusion Human Plasmodium existence among domestic animals in Indonesia partly explains the high prevalence and persistence of malaria in some endemic areas due to a reservoir host presence. Therefore, future studies need to ascertain the cause.

Modeling of the Spread of Malaria in the Bangka Belitung Islands Province Using the SEIR Method

Malaria is an infectious disease caused by plasmodium through the bite of the Anopheles sp mosquito. female (Roach, 2012). Malaria disease which hit the Bangka Belitung Islands Province in 2005 experienced a spike, reaching 36,901 people out of 981,573 residents and claimed the lives of 12 local residents. In 2011, the Bangka Belitung Islands Province was declared an endemic area for malaria. This research aims to model and interpret the spread of malaria using the SEIR model and predict the spread of malaria using parameter estimates. The steps in analyzing the SEIR model on the spread of malaria are making assumptions, forming a SEIR model, determining the equilibrium point and analyzing the stability of the equilibrium point, determining the basic reproduction number, and carrying out a simulation of the SEIR model that has been obtained. The SEIR model is classified into 4 classes, namely Susceptible (susceptible individuals), Exposed (individuals who have symptoms), Infected (infected individuals), and Recovered (recovered individuals). The data used in this research is data on the number of Susceptible, Exposed, Infected and Recovered malaria cases in 2022 obtained from the Bangka Belitung Islands Provincial Health Service. The SEIR mathematical model is used to calculate the equilibrium point and basic reproduction number. Based on the SEIR model simulation results, it was found that the susceptible population decreased from the 0th month to the 48th month. As for the exposed population, there were 9,623 people in month 0, but in this condition the population decreased drastically per month. Furthermore, for the infected population there were 129 people in month 0, but in this condition the number of infected decreased drastically per month along with the decrease in the exposed population. For individuals who recovered, there was a decrease from the 0th month to the 48th month.

Challenges of diagnosing severe malaria with complications in adult patients: a case report

BackgroundMalaria is known to be the main cause of death in malaria-endemic areas. The authors report a case of severe malaria in an adult with no history of travel from an endemic area with good outcomes after hospitalization.Case presentationA 46-year-old man was brought to the Emergency Room (ER) because of fever and chills for 6 days. Complaints were accompanied by nausea and vomiting three times a day. The patient also experienced headaches, weakness, coughing, and a runny nose after two days of admission. The patient had no history of traveling from a malaria-endemic area. The patient was transferred from the Emergency Department (ED) to the High Care Unit (HCU), and during 1 day of intensive care at the HCU, there was a clinical deterioration characterized by dyspnea, icteric sclerae, acral edema, tenderness in both calves, and rash in the abdominal area. Due to worsening respiratory function, the patient was placed on a ventilator. During intensive treatment, the patient continued to show deterioration. The clinical findings suggested a possible feature of Weil’s disease or fulminant hepatitis, and although the patient was in intensive care, there was no clinically significant improvement. Furthermore, microscopic blood smear examination and rapid diagnostic tests (RDTs) for malaria were carried out on the 4th day of treatment with negative results. As there was no clinically significant improvement, it was decided to take a blood smear and repeat RDT on the twelfth day, which showed a positive result for falciparum malaria. Subsequently, artesunate was administered intravenously, and the patient’s condition began to improve with a negative parasite count the following day. The patient was discharged in good clinical condition on day 25 of treatment.ConclusionGood quality malaria diagnostic techniques are essential to diagnose malaria. A timely diagnosis of malaria has the potential to save the patient. Because Jakarta is not a malaria endemic area, it was concluded that this case was an introduced malaria case.

Blood count abnormalities in the association of sickle cell disease and malaria in clinical hematology at the CNHU-HKM in Cotonou (Bénin)

Although a protective effect of hemoglobin S has been described, malaria has frequently been associated with increased morbidity and mortality in sickle cell disease patients in Africa. Various cytopenias are frequently found on the haemograms of these patients. In Benin, a malaria-endemic zone with a high prevalence of sickle cell disease, the aim of this study was to establish and compare the blood count profile according to hemoglobin type in the association of sickle cell disease and malaria. This was a prospective descriptive study. It covered a 24-month period from October 2020 to October 2022. It included all patients with major sickle cell syndrome seen in clinical haematology and with a positive thick drop/parasite density, whatever the parasitaemia value. For each patient, a blood count was performed on the Sysmex XT 4000i machine, supplemented by a smear study after staining with May-Grunwald Giemsa. Data were analyzed using R 3.6.1 software. Three hundred non-redundant cases with a positive thick smear were identified in sickle cell patients, including 208 SS homozygotes (69.3%) and 92 SC heterozygotes (30.7%). In contrast, there were 181 non-redundant cases with a negative thick smear, including 119 SS homozygotes (65.7%) and 62 SC heterozygotes (34.3%). Among subjects with a positive thick smear, the majority of patients (70%) exhibited clinical symptoms. Severe malaria was observed in 58% of the cases. The proportion of severe malaria was higher in SS homozygote patients than in double heterozygote SC patients (p < 0.0001). The mean parasite density was higher in SS individuals (4 320.7 ± 2 185 trophozoites/pL) compared to SC individuals (1 564.4 ± 1 221 trophozoites/pL; p < 0.0001). Plasmodium falciparum was the only species identified. The mean hemoglobin level in impaludated SS subjects was 6.1 g/dL, significantly lower than that in non-impaludated SS subjects (p < 0.0001). The average white blood cell count in impaludated SS subjects was 16.58 G/L, compared to 13.2 G/L in those with a negative thick smear (p < 0.0001). Twenty cases of thrombocytopenia were found in SS subjects with a positive thick smear, compared to 6 cases in those with a negative thick smear. As for SC subjects with a positive thick smear, the average hemoglobin levels and white blood cell counts were 9.8 g/dL and 10.63 G/L, respectively, compared to 11.27 g/dL and 7.3 G/L in SC subjects with a negative thick smear. Eighteen cases of thrombocytopenia were found in subjects with a positive thick smear, compared to 17 cases in those with a negative thick smear. Sickle cell disease and malaria represent two major public health problems. However, contrary to popular belief, sickle cell disease is not immune to malaria infestation. Malaria is recognized as one of the main causes of morbidity and mortality in sickle cell patients, particularly children. In Benin, its association with sickle cell emergencies has already been reported.Our study found that malaria was predominantly associated with the homozygous SS form (p < 0.00001). Severe malaria was the most common clinical form. All malaria infestations in our series were due to Plasmodium falciparum, and parasitaemia was significantly higher in SS patients (p < 0.0001).The hematological profile of the association of sickle cell disease and malaria in homozygous SS individuals in our series showed characteristics of a normocytic normochromic anemia with neutrophil-predominant leukocytosis. Compared to non-malaria-infected SS individuals, there was a significant worsening of anemia, neutrophil-predominant leukocytosis, and a decrease in the average platelet count. In SC individuals, there was rather a microcytic normochromic regenerative anemia associated with neutrophil-predominant leukocytosis. Compared to non-malaria-infected SC individuals, there was a significant decrease in the rate of anemia and neutrophil-predominant leukocytosis. Anemia is a constant feature in homozygous sickle cell disease, and the low values recorded illustrate the hemolytic nature of malaria, especially in SS individuals, and the better tolerance of SC individuals. Furthermore, the low baseline hemoglobin levels make SS individuals more vulnerable to malaria-induced anemia compared to SC individuals. The observed leukocytosis is generally accompanied by reticulocytosis in the case of major sickle cell syndrome, which must be taken into account for result validation. It is the expression of compensatory bone marrow reaction to anemia and inflammatory mechanisms resulting from malaria infestation. Finally, thrombocytopenia was significantly more common in SC patients, even though they were adults living in malaria-endemic areas. Malaria can frequently induce thrombocytopenia through platelet consumption during the "rosetting" phenomenon. In SS patients, the effects of "rosetting" could be compensated for by the bone marrow stimulation induced by anemia. In our series with adult subjects living in an endemic area, thrombocytopenia is not a frequent biological disturbance. In a clinicalbiological context combining a systemic inflammatory response syndrome with anemia and neutrophil-predominant leukocytosis in a SS or SC sickle cell patient, the clinician should be able to consider malaria and confirm or rule out this diagnosis.

Relative Frequency (Composition) of Anopheles sp. Mosquitoes as Malaria Vectors in Kulon Progo District Special Region of Yogyakarta

Malaria is caused by Plasmodium infection transmitted Anopheles sp. One of the obstacles in malaria control is the variation of Anopheles sp. Species which have various characteristics and behaviour, so it’s very important to understand the species of Anopheles sp. with aim to develop the disease control program. This study was conducted in Kulon Progo Regency, Yogyakarta, one of the malaria endemic areas in Indonesia. Data collection of Anopheles sp. species diversity was carried out through landing collection inside and outside people’s homes at 18.00 - 06.00 WIB. Observations of abiotics factors in the habitat of Anopheles sp. larvae was carried out around the landing collection location. The result of research conducted in the Samigaluh, Kalibawang, and Pengasih Sub-Districts showed that the most common species found was Anopeheles vagus. The dominance of Anopheles vagus occurred in the Kalibawang and Pengasih dictricts, while in the Samigaluh Sub-Districts it became the second most among other species. Measurement of abiotic factors in the habitat of Anopheles sp. larvae through the parameters of temperature, air humidity, pH DO of water shows that the location where the larvae were found can support larval breeding and growth. That can be a factor in the large population of Anopheles sp., especially Anopheles vagus, which is a known vector of malarias based on research and its vectorial capacity.

Impact of climate change on temperature variations and extrinsic incubation period of malaria parasites in Chennai, India: implications for its disease transmission potential

BackgroundThe global temperature has significantly risen in the past century. Studies have indicated that higher temperature intensifies malaria transmission in tropical and temperate countries. Temperature fluctuations will have a potential impact on parasite development in the vector Anopheles mosquito.MethodsYear-long microclimate temperatures were recorded from a malaria-endemic area, Chennai, India, from September 2021 to August 2022. HOBO data loggers were placed in different vector resting sites including indoor and outdoor roof types. Downloaded temperatures were categorised by season, and the mean temperature was compared with data from the same study area recorded from November 2012 to October 2013. The extrinsic incubation period for Plasmodium falciparum and P. vivax was calculated from longitudinal temperatures recorded during both periods. Vector surveillance was also carried out in the area during the summer season.ResultsIn general, temperature and daily temperature range (DTR) have increased significantly compared to the 2012–2013 data, especially the DTR of indoor asbestos structures, from 4.30 ℃ to 12.62 ℃ in 2021–2022, unlike the marginal increase observed in thatched and concrete structures. Likewise, the average DTR of outdoor asbestos structures increased from 5.02 ℃ (2012–2013) to 8.76 ℃ (2021–2022) although the increase was marginal in thatched structures and, surprisingly, showed no such changes in concrete structures. The key finding of the extrinsic incubation period (EIP) is that a decreasing trend was observed in 2021–2022 compared to 2012–2013, mainly in indoor asbestos structures from 7.01 to 6.35 days, which negatively correlated with the current observation of an increase in temperature. Vector surveillance undertaken in the summer season revealed the presence of Anopheles breeding in various habitats. Anopheles stephensi could be collected using CDC light traps along with other mosquito species.ConclusionThe microclimate temperature has increased significantly over the years, and mosquitoes are gradually adapting to this rising temperature. Temperature negatively correlates with the extrinsic incubation period of the parasite. As the temperature increases, the development of the parasite in An. stephensi will be faster because of a decrease in EIP, thus requiring relatively fewer days, posing a risk for disease transmission and a hindrance to malaria elimination efforts.Graphical

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

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

Malaria blood stage infection suppresses liver stage infection via host-induced interferons but not hepcidin

Malaria-causing Plasmodium parasites first replicate as liver stages (LS), which then seed symptomatic blood stage (BS) infection. Emerging evidence suggests that these stages impact each other via perturbation of host responses, and this influences the outcome of natural infection. We sought to understand whether the parasite stage interplay would affect live-attenuated whole parasite vaccination, since the efficacy of whole parasite vaccines strongly correlates with their extend of development in the liver. We thus investigated the impact of BS infection on LS development of genetically attenuated and wildtype parasites in female rodent malaria models and observed that for both, LS infection suffered severe suppression during concurrent BS infection. Strikingly and in contrast to previously published studies, we find that the BS-induced iron-regulating hormone hepcidin is not mediating suppression of LS development. Instead, we demonstrate that BS-induced host interferons are the main mediators of LS developmental suppression. The type of interferon involved depended on the BS-causing parasite species. Our study provides important mechanistic insights into the BS-mediated suppression of LS development. This has direct implications for understanding the outcomes of live-attenuated Plasmodium parasite vaccination in malaria-endemic areas and might impact the epidemiology of natural malaria infection.

The synthesis of nanosilver and carbamat to control of Anopheles in malaria endemic areas

Malaria is a national and global problem that really needs attention and Indonesia is the second highest country with the highest number of cases 304,607 in 2021. The use of insecticides at inappropriate doses causes resistance to targets. The aim of this study was to analyze the toxicity of silver nanoparticles to adult Anopheles mosquitoes in malaria endemic areas as well as to determine the lethal concentration (LC50) and to project effectiveness in the lifetime. This research is experimental and uses a post-treatment with control design which was carried out in 4 stages from 2019-2022, which includes laboratory scale tests (2019), field laboratory scale tests (2020), ecological endemic area scale tests (2021), and lifetime tests (2022). Calculation of LC50 in nanosilver toxicity 5965 mg/l and Calculation of life time projections produces the formula Y=(-) 0.012Ln(X)+0.6933. Absorption of silver nanoparticles into the bodies of Anopheles sp. occurs through the spiracles and attacks the Ache enzyme in the central nervous system thereby stopping the working system of the mosquito which will then die. Nanosilver is a very effective herbal insecticide used as an effort to control malaria cases in endemic areas with the right dose and method. For life time, a dose of 1500 mg/l nanosilver effectively kills 74% of adult Anopheles sp mosquitoes on day 32 and it is projected that on 1 year the efficacy of nanomaterials still has an efficacy of 62%).

How using light touch immersion research revealed important insights into the lack of progress in malaria elimination in Eastern Indonesia.

By 2022, the Government of Indonesia had successfully eliminated malaria in 389 out of 514 districts but continues to face a challenge in Eastern Indonesia where 95% of the total 2021 malaria cases were reported from Papua, West Papua and Nusa Tenggara Timur provinces. There is an increased recognition that malaria elimination will require a better understanding of the human behavioural factors hindering malaria prevention and treatment, informed by local context and local practice. This research used a light-touch immersion research approach. Field researchers lived in communities over several days to gather data through informal conversations, group-based discussions using visual tools, participant observation and direct experience. The study was conducted in four high malaria endemic areas in Papua, West Papua, and Sumba Islands in Nusa Tenggara Timur. The research highlights how people's perception of malaria has changed since the introduction of effective treatment which, in turn, has contributed to a casual attitude towards early testing and adherence to malaria treatment. It also confirms that people rarely accept there is a link between mosquitoes and malaria based on their experience but nevertheless take precautions against the annoyance of mosquitoes. There is widespread recognition that babies and small children, elderly and incomers are more likely to be seriously affected by malaria and separately, more troubled by mosquitoes than indigenous adult populations. This is primarily explained by acclimatization and strong immune systems among the latter. Using immersion research enabled behaviour research within a naturalistic setting, which in turn enabled experiential-led analysis of findings and revealed previously unrecognized insights into attitudes towards malaria in Eastern Indonesia. The research provides explanations of people's lack of motivation to consistently use bed nets, seek early diagnosis or complete courses of treatment. The felt concern for the wellbeing of vulnerable populations highlighted during light touch immersion provides an entry point for future social behaviour change communication interventions. Rather than trying to explain transmission to people who deny this connection, the research concludes that it may be better to focus separately on the two problems of malaria and mosquitoes (especially for vulnerable groups) thereby resonating with local people's own experience and felt concerns.

Factors Associated with Malaria in Pregnancy among Women Attending Fort Portal Regional Referral Hospital in Fort Portal City, Western Uganda

Globally, there was a significant decrease in the number of malaria-risk pregnancies between 2007 and 2020. The risk of Plasmodium falciparum or Plasmodium vivax malaria increased by 25% in Africa compared to 2007. Due to the fast-expanding population and associated rise in pregnancies in malaria-endemic areas, the number of people at risk in Africa has increased despite malaria rates declining in the region. This study determined the prevalence and factors associated with malaria in pregnancy among women attending Fort Portal Regional Referral Hospital. This was a single-center health facility-based cross-sectional study. Data was collected using a face-to-face interview through a structured questionnaire from willing participants. After collecting the data, the principal investigator checked the completed questionnaires for consistency and completeness. Data was coded, cleaned, and entered into the computer using Microsoft Excel, and then analyzed using SPSS version 20. Logistic regression analysis was done to ascertain the relationship between dependent and independent variables. Descriptive statistics were summarized in the form of frequency tables, pie charts, p-values, and odds ratios. A total of 253 pregnant mothers attending ANC were enrolled in this study. The majority (38.3%) of the study participants were aged 30-39 years, attained secondary education (52.2%), earned 100,000–200,000 per month (56.9%), and were housewives (51.0%). In this study, the prevalence of malaria in pregnancy was 10.3%. Age, level of education, income status, and residence, use of an ITN, gravidity, and ANC follow-up were significantly associated with malaria in pregnancy at multivariate logistic regression analysis. Malaria continues to be a major public health issue among pregnant mothers. Age, level of education, income status, and residence, use of an ITN, gravidity, and ANC follow-up were factors significantly associated with malaria in pregnancy. Keywords: Pregnancies, Malaria, Plasmodium, ITN, ANC.

Prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Gia Lai Province, Vietnam

Glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) deficiency is one of the most common X-linked hereditary disorders worldwide. G6PD deficiency provides resistance against severe malaria, but paradoxically, G6PD deficiency is also a stumbling block in fighting against malaria. Primaquine (PQ), a drug for the radical cure of Plasmodium vivax, can cause lethal acute hemolytic anemia in malaria patients with inherited G6PD deficiency. In this study, we analyzed the phenotypic and genotypic G6PD deficiency status in 1721 individuals (963 males and 758 females) residing in three malaria-endemic areas within the Gia Lai province, Vietnam. The G6PD activity in individuals ranged from 3.04 to 47.82 U/g Hb, with the adjusted male median (AMM) of 7.89 U/g Hb. Based on the G6PD activity assay results, no phenotypic G6PD deficiency was detected. However, the multiplex polymerase chain reaction to detect G6PD variations in the gene level revealed that 26 individuals (7 males, 19 females) had Viangchan mutations (871 G > A). Sequencing analyses suggested that all the males were hemizygous Viangchan, whereas one was homozygous, and 18 were heterozygous Viangchan in females. These results suggested a relatively low prevalence of G6PD deficiency mutation rate (1.51%) in the minor ethnic populations residing in the Gia Lai province, Vietnam. However, considering these areas are high-risk malaria endemic, concern for proper and safe use of PQ as a radical cure of malaria is needed by combining a G6PD deficiency test before PQ prescription.

Conducting active screening for human African trypanosomiasis with rapid diagnostic tests: The Guinean experience (2016-2021).

Strategies to detect Human African Trypanosomiasis (HAT) cases rely on serological screening of populations exposed to trypanosomes. In Guinea, mass medical screening surveys performed with the Card Agglutination Test for Trypanosomiasis have been progressively replaced by door-to-door approaches using Rapid Diagnostic Tests (RDTs) since 2016. However, RDTs availability represents a major concern and medical teams must often adapt, even in the absence of prior RDT performance evaluation. For the last 5 years, the Guinean HAT National Control Program had to combine three different RDTs according to their availability and price: the SD Bioline HAT (not available anymore), the HAT Sero-K-SeT (most expensive), and recently the Abbott Bioline HAT 2.0 (limited field evaluation). Here, we assess the performance of these RDTs, alone or in different combinations, through the analysis of both prospective and retrospective data. A parallel assessment showed a higher positivity rate of Abbott Bioline HAT 2.0 (6.0%, n = 2,250) as compared to HAT Sero-K-SeT (1.9%), with a combined positive predictive value (PPV) of 20.0%. However, an evaluation of Abbott Bioline HAT 2.0 alone revealed a low PPV of 3.9% (n = 6,930) which was surpassed when using Abbott Bioline HAT 2.0 in first line and HAT Sero-K-SeT as a secondary test before confirmation, with a combined PPV reaching 44.4%. A retrospective evaluation of all 3 RDTs was then conducted on 189 plasma samples from the HAT-NCP biobank, confirming the higher sensitivity (94.0% [85.6-97.7%]) and lower specificity (83.6% [76.0-89.1%]) of Abbott Bioline HAT 2.0 as compared to SD Bioline HAT (Se 64.2% [52.2-74.6%]-Sp 98.4% [94.2-99.5%]) and HAT Sero-K-SeT (Se 88.1% [78.2-93.8%]-Sp 98.4% [94.2-99.5%]). A comparison of Abbott Bioline HAT 2.0 and malaria-RDT positivity rates on 479 subjects living in HAT-free malaria-endemic areas further revealed that a significantly higher proportion of subjects positive in Abbott Bioline HAT 2.0 were also positive in malaria-RDT, suggesting a possible cross-reaction of Abbott Bioline HAT 2.0 with malaria-related biological factors in about 10% of malaria cases. This would explain, at least in part, the limited specificity of Abbott Bioline HAT 2.0. Overall, Abbott Bioline HAT 2.0 seems suitable as first line RDT in combination with a second HAT RDT to prevent confirmatory lab overload and loss of suspects during referral for confirmation. A state-of-the-art prospective comparative study is further required for comparing all current and future HAT RDTs to propose an optimal combination of RDTs for door-to-door active screening.

Primaquine in glucose-6-phosphate dehydrogenase deficiency: an adaptive pharmacometric assessment of ascending dose regimens in healthy volunteers

Background:Primaquine is an 8-aminoquinoline antimalarial. It is the only widely available treatment to prevent relapses of Plasmodium vivax malaria. The 8-aminoquinolines cause dose-dependent haemolysis in glucose-6-phosphate dehydrogenase deficiency (G6PDd). G6PDd is common in malaria endemic areas but testing is often not available. As a consequence primaquine is underused.Methods:We conducted an adaptive pharmacometric study to characterise the relationship between primaquine dose and haemolysis in G6PDd. The aim was to explore shorter and safer primaquine radical cure regimens compared to the currently recommended 8-weekly regimen (0.75 mg/kg once weekly), potentially obviating the need for G6PD testing. Hemizygous G6PDd healthy adult Thai and Burmese male volunteers were admitted to the Hospital for Tropical Diseases in Bangkok. In Part 1, volunteers were given ascending dose primaquine regimens whereby daily doses were increased from 7.5 mg up to 45 mg over 15–20 days. In Part 2 conducted at least 6 months later, a single primaquine 45 mg dose was given.Results:24 volunteers were enrolled in Part 1, and 16 in Part 2 (13 participated in both studies). In three volunteers, the ascending dose regimen was stopped because of haemolysis (n=1) and asymptomatic increases in transaminases (n=2; one was hepatitis E positive). Otherwise the ascending regimens were well tolerated with no drug-related serious adverse events. In Part 1, the median haemoglobin concentration decline was 3.7 g/dL (range: 2.1–5.9; relative decline of 26% [range: 15–40%]). Primaquine doses up to 0.87 mg/kg/day were tolerated subsequently without clinically significant further falls in haemoglobin. In Part 2, the median haemoglobin concentration decline was 1.7 g/dL (range 0.9–4.1; relative fall of 12% [range: 7–30% decrease]). The ascending dose primaquine regimens gave seven times more drug but resulted in only double the haemoglobin decline.Conclusions:In patients with Southeast Asian G6PDd variants, full radical cure treatment can be given in under 3 weeks compared with the current 8-week regimen.Funding:Medical Research Council of the United Kingdom (MR/R015252/1) and Wellcome (093956/Z/10/C, 223253/Z/21/Z).Clinical trial number:Thai Clinical Trial Registry: TCTR20170830002 and TCTR20220317004.