Prevalence Of Plasmodium Falciparum Infection Research Articles

A Non-Coding Fc Gamma Receptor Cis-Regulatory Variant within the 1q23 Gene Cluster Is Associated with Plasmodium falciparum Infection in Children Residing in Burkina Faso

Antibodies play a crucial role in activating protective immunity against malaria by interacting with Fc-gamma receptors (FcγRs). Genetic variations in genes encoding FcγRs can affect immune cell responses to the parasite. In this study, our aim was to investigate whether non-coding variants that regulate FcγR expression could influence the prevalence of Plasmodium falciparum infection. Through bioinformatics approaches, we selected expression quantitative trait loci (eQTL) for FCGR2A, FCGR2B, FCGR2C, FCGR3A, and FCGR3B genes encoding FcγRs (FCGR), in whole blood. We prioritized two regulatory variants, rs2099684 and rs1771575, located in open genomic regions. These variants were identified using RegVar, ImmuNexUT, and transcription factor annotations specific to immune cells. In addition to these, we genotyped the coding variants FCGR2A/rs1801274 and FCGR2B/rs1050501 in 234 individuals from a malaria-endemic area in Burkina Faso. We conducted age and family-based analyses to evaluate associations with the prevalence of malarial infection in both children and adults. The analysis revealed that the regulatory rs1771575-CC genotype was predicted to influence FCGR2B/FCGR2C/FCGR3A transcripts in immune cells and was the sole variant associated with a higher prevalence of malarial infection in children. In conclusion, this study identifies the rs1771575 cis-regulatory variant affecting several FcγRs in myeloid and neutrophil cells and associates it with the inter-individual capacity of children living in Burkina Faso to control malarial infection.

Evaluating the Prevalence of Malaria Parasite Infection among Adults in Wetlands Using Nested PCR and High Resolution Melting Analysis

Background: Wetlands serve as breeding grounds for mosquitoes, the vector of malaria Plasmodium. Effective detection of Plasmodium infection requires a very sensitive method.
 Aim: The aim of the present study was to evaluate the prevalence of malaria parasite infection in Sagbama LGA, Bayelsa State using nested PCR and high resolution melting analysis (HRMA) technique in comparison with microscopy.
 Methods: A community based cross sectional study design was employed to randomly select 206 study participants. DNA was extracted from 200 ⴗl of whole blood of each participant and a set of primers was used to target and amplify the 18S rRNA gene of Plasmodium falciparum in both molecular methods.
 Result: The prevalence of Plasmodium falciparum infection by microscopy was 33.01% (5.8% asymptomatic, 17% mild and 10.2% severe malaria).The prevalence of malaria parasite infection by nested genomic PCR was 71.36% (asymptomatic, 42.20% mild, 18.93%and severe malaria, 10.19%). Prevalence of malaria parasite infection by high resolution melting analysis 92.71% (asymptomatic, 63.59%, mild, 18.93% and severe, 10.19%). All the study participants that were positive for microscopy and nested genomic PCR were also positive for high resolution melting analysis. There were 59.71% and 21.36% false negatives by microscopy and nested PCR respectively. McNemar`s test for pair-wise performance comparisons among the different methods was statistically significant (p < 0.001). High parasite density (19927 ± 749 parasites/µl blood) and hyper parasite density (103667 ± 5214 parasites/ⴗl of blood) were found among asymptomatic and severe malaria subjects (P < 0.000).
 Conclusion: In conclusion, a high malaria parasite infection prevalence of 92.72% was found in Sagbama LGA. This requires urgent attention especially asymptomatic malaria. HRMA was the most sensitive molecular method and is therefore recommended for future molecular detection of malaria infection.

Prevalence of Plasmodium falciparum infection in children under 15 years in two oil palm plantations in Aboisso, Côte d'Ivoire

Prevalence of Plasmodium falciparum infection in children under 15 years in two oil palm plantations in Aboisso, Côte d'Ivoire

Plasmodium falciparum infection prevalence among children aged 6–59 months from independent DHS and HIV surveys: Nigeria, 2018

Prevalence estimates are critical for malaria programming efforts but generating these from non-malaria surveys is not standard practice. Malaria prevalence estimates for 6–59-month-old Nigerian children were compared between two national household surveys performed simultaneously in 2018: a Demographic and Health Survey (DHS) and the Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS). DHS tested via microscopy (n = 8298) and HRP2-based rapid diagnostic test (RDT, n = 11,351), and NAIIS collected dried blood spots (DBS) which were later tested for histidine-rich protein 2 (HRP2) antigen (n = 8029). National Plasmodium falciparum prevalence was 22.6% (95% CI 21.2– 24.1%) via microscopy and 36.2% (34.6– 37.8%) via RDT according to DHS, and HRP2 antigenemia was 38.3% (36.7–39.9%) by NAIIS DBS. Between the two surveys, significant rank-order correlation occurred for state-level malaria prevalence for RDT (Rho = 0.80, p < 0.001) and microscopy (Rho = 0.75, p < 0.001) versus HRP2. RDT versus HRP2 positivity showed 24 states (64.9%) with overlapping 95% confidence intervals from the two independent surveys. P. falciparum prevalence estimates among 6–59-month-olds in Nigeria were highly concordant from two simultaneous, independently conducted household surveys, regardless of malaria test utilized. This provides evidence for the value of post-hoc laboratory HRP2 detection to leverage non-malaria surveys with similar sampling designs to obtain accurate P. falciparum estimates.

Altitude, not potential larval habitat availability, explains pronounced variation in Plasmodium falciparum infection prevalence in the western Kenya highlands

Progress in malaria control has stalled over the recent years. Knowledge on main drivers of transmission explaining small-scale variation in prevalence can inform targeted control measures. We collected finger-prick blood samples from 3061 individuals irrespective of clinical symptoms in 20 clusters in Busia in western Kenya and screened for Plasmodium falciparum parasites using qPCR and microscopy. Clusters spanned an altitude range of 207 meters (1077-1284 m). We mapped potential mosquito larval habitats and determined their number within 250 m of a household and distances to households using ArcMap. Across all clusters, P. falciparum parasites were detected in 49.8% (1524/3061) of individuals by qPCR and 19.5% (596/3061) by microscopy. Across the clusters, prevalence ranged from 26% to 70% by qPCR. Three to 34 larval habitats per cluster and 0-17 habitats within a 250m radius around households were observed. Using a generalized linear mixed effect model (GLMM), a 5% decrease in the odds of getting infected per each 10m increase in altitude was observed, while the number of larval habitats and their proximity to households were not statistically significant predictors for prevalence. Kitchen located indoors, open eaves, a lower level of education of the household head, older age, and being male were significantly associated with higher prevalence. Pronounced variation in prevalence at small scales was observed and needs to be taken into account for malaria surveillance and control. Potential larval habitat frequency had no direct impact on prevalence.

The circadian clock modulates Anopheles gambiae infection with Plasmodium falciparum.

Key behaviours, physiologies and gene expressions in Anopheles mosquitoes impact the transmission of Plasmodium. Such mosquito factors are rhythmic to closely follow diel rhythms. Here, we set to explore the impact of the mosquito circadian rhythm on the tripartite interaction between the vector, the parasite and the midgut microbiota, and investigate how this may affect the parasite infection outcomes. We assess Plasmodium falciparum infection prevalence and intensity, as a proxy for gametocyte infectivity, in Anopheles gambiae mosquitoes that received a gametocyte-containing bloodfeed and measure the abundance of the midgut microbiota at different times of the mosquito rearing light-dark cycle. Gametocyte infectivity is also compared in mosquitoes reared and maintained under a reversed light-dark regime. The effect of the circadian clock on the infection outcome is also investigated through silencing of the CLOCK gene that is central in the regulation of animal circadian rhythms. The results reveal that the A. gambiae circadian cycle plays a key role in the intensity of infection of P. falciparum gametocytes. We show that parasite gametocytes are more infectious during the night-time, where standard membrane feeding assays (SMFAs) at different time points in the mosquito natural circadian rhythm demonstrate that gametocytes are more infectious when ingested at midnight than midday. When mosquitoes were cultured under a reversed light/dark regime, disrupting their natural physiological homeostasis, and infected with P. falciparum at evening hours, the infection intensity and prevalence were significantly decreased. Similar results were obtained in mosquitoes reared under the standard light/dark regime upon silencing of CLOCK, a key regulator of the circadian rhythm, highlighting the importance of the circadian rhythm for the mosquito vectorial capacity. At that time, the mosquito midgut microbiota load is significantly reduced, while the expression of lysozyme C-1 (LYSC-1) is elevated, which is involved in both the immune response and microbiota digestion. We conclude that the tripartite interactions between the mosquito vector, the malaria parasite and the mosquito gut microbiota are finely tuned to support and maintain malaria transmission. Our data add to the knowledge framework required for designing appropriate and biologically relevant SMFA protocols.

Impact of Agricultural Irrigation on Anemia in Western Kenya.

Expanding agricultural irrigation efforts to enhance food security and socioeconomic development in sub-Saharan Africa may affect malaria transmission and socioeconomic variables that increase the risk of anemia in local communities. We compared the prevalence of anemia, Plasmodium falciparum infection, and indicators of socioeconomic status related to nutrition in communities in Homa Bay County, Kenya, where an agricultural irrigation scheme has been implemented, to that in nearby communities where there is no agricultural irrigation. Cross-sectional surveys conducted showed that anemia prevalence defined by WHO criteria (hemoglobin < 11 g/dL) was less in communities in the irrigated areas than in the non-irrigated areas during the wet season (38.9% and 51.5%, χ2 = 4.29, P = 0.001) and the dry season (25.2% and 34.1%, χ2 = 7.33, P = 0.007). In contrast, Plasmodium falciparum infection prevalence was greater during the wet season in irrigated areas than in non-irrigated areas (15.3% versus 7.8%, χ2 = 8.7, P = 0.003). There was, however, no difference during the dry season (infection prevalence, < 1.8%). Indicators of nutritional status pertinent to anemia pathogenesis such as weekly consumption of non-heme- and heme-containing foods and household income were greater in communities located within the irrigation scheme versus those outside the irrigation scheme (P < 0.0001). These data indicate that current agricultural irrigation schemes in malaria-endemic communities in this area have reduced the risk of anemia. Future studies should include diagnostic tests of iron deficiency, parasitic worm infections, and genetic hemoglobin disorders to inform public health interventions aimed at reducing community anemia burden.

Prevalence of Plasmodium falciparum Infection among HIV Patients Attending Selected Hospitals in Niger State, Nigeria

Malaria and Acquired Immune Deficiency Syndrome (AIDS) are among the world’s greatest health problems and are concentrated in the tropical and sub-tropical regions of the world. Together, they are the cause of death of millions of people each year, hence they become a burden and a threat for development in India, Southern Asia, South America and Africa including Nigeria. The prevalence of malaria among HIV patients attending selected hospitals in Niger State, Nigeria was determined. A total of 300 HIV patients within the age range of 2-69years were enrolled, of which 217 were females and 83 were males. Four (4) mL of venous blood was drawn from each participant. The blood samples were examined for the presence of Plasmodium falciparum using thin and thick films while the CD4count was determined using flow cytometer (Partec Cyflow). Plasmodium falciparum was detected in 43 out of 300 participants with a prevalence of 14.3%.The prevalence was observed to be higher in males (18.07%) than in females (12.90%) and in the age group 1-10years (28.57%). Statistically, there was no association between Plasmodium falciparum infection with sex (p = 0.223) or age (p =0.253). The CD4 counts of all the participants ranges between 28-2000 cells/μL with a mean of 1111.40 + 739.589. Patients with Plasmodium falciparum infection had lower CD4 counts than those that were negative. Conclusively, HIV individuals with severe immunosuppression (CD4 counts &lt;200 cells/µL) are at higher risk of Plasmodium falciparum infection. Hence, HIV individuals should take all necessary measures to prevent the infection to avoid the negative impact.

Persistent Plasmodium falciparum infections enhance transmission-reducing immunity development

Subclinical infections that serve as reservoir populations to drive transmission remain a hurdle to malaria control. Data on infection dynamics in a geographical area is required to strategically design and implement malaria interventions. In a longitudinal cohort, we monitored Plasmodium falciparum infection prevalence and persistence, and anti-parasite immunity to gametocyte and asexual antigens for 10 weeks. Of the 100 participants, only 11 were never infected, whilst 16 had persistent infections detected by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR), and one participant had microscopic parasites at all visits. Over 70% of the participants were infected three or more times, and submicroscopic gametocyte prevalence was high, ≥ 48% of the parasite carriers. Naturally induced responses against recombinant Pfs48/45.6C, Pfs230proC, and EBA175RIII–V antigens were not associated with either infection status or gametocyte carriage, but the antigen-specific IgG titers inversely correlated with parasite and gametocyte densities consistent with partial immunity. Longitudinal analysis of gametocyte diversity indicated at least four distinct clones circulated throughout the study period. The high prevalence of children infected with distinct gametocyte clones coupled with marked variation in infection status at the individual level suggests ongoing transmission and should be targeted in malaria control programs.

Seasonal prevalence of Plasmodium falciparum infection and use of insecticide-treated nets among children in three agroecosystems in Aboisso, Côte d'Ivoire.

Agroecosystems have been associated with risk of malaria. The aim of this study was to determine the relationship between three agroecosystems: (i) rubber plantation (RP); (ii) oil palm plantation (OPP); (iii) no cash crop plantation (NCCP) and the prevalence of Plasmodium falciparum infection among children living in the Aboisso region. In the three villages within (Ehania-V5) or close (N'zikro) or far from (Ayébo) to each agroecosystem (RP, OPP, and NCCP), two cross-sectional parasitological surveys were carried out during the dry and the peak of the long wet seasons. A total of 586 children aged 1-14years were recruited in the three villages to determine the prevalence of malaria using conventional microscopy. Plasmodium falciparum was the dominant species with an overall infection prevalence of 40.8%. There was a significant difference in prevalence between agroecosystems, during both the dry (p = 0.002) and wet seasons (p < 0.001), which was higher in agricultural settings compared with the NCCP environment, whatever the season. The prevalence of P. falciparum infection increased from the dry to the wet season in agricultural settings (RP and OPP), whereas no difference was noted for NCCP. Less than 18% of children use insecticide-treated nets (ITNs) in the three villages, ranging from 6 (in RP) to 30% (in OPP). Multivariate analysis indicated that age (1-4; 5-9; and 10-14years) was not associated with malaria risk, but the season and living in agricultural villages were associated with a greater risk of malaria infection. Risk of malaria exposure was fourfold higher in children from agricultural villages than their counterpart from the non-agricultural area. Our findings highlight significant variations in the prevalence of P. falciparum according to agroecosystem and season. The findings will be useful in designing and implementing malaria control interventions by the National Malaria Control Program.

Nonrandom Selection and Multiple Blood Feeding of Human Hosts by Anopheles Vectors: Implications for Malaria Transmission in Papua New Guinea.

ABSTRACT.Nonrandom selection and multiple blood feeding of human hosts by Anopheles mosquitoes may exacerbate malaria transmission. Both patterns of blood feeding and their relationship to malaria epidemiology were investigated in Anopheles vectors in Papua New Guinea (PNG). Blood samples from humans and mosquito blood meals were collected in villages and human genetic profiles (“fingerprints”) were analyzed by genotyping 23 microsatellites and a sex-specific marker. Frequency of blood meals acquired from different humans, identified by unique genetic profiles, was fitted to Poisson and negative binomial distributions to test for nonrandom patterns of host selection. Blood meals with more than one genetic profiles were classified as mosquitoes that fed on multiple humans. The age of a person bitten by a mosquito was determined by matching the blood-meal genetic profile to the villagers’ genetic profiles. Malaria infection in humans was determined by PCR test of blood samples. The results show nonrandom distribution of blood feeding among humans, with biased selection toward males and individuals aged 15–30 years. Prevalence of Plasmodium falciparum infection was higher in this age group, suggesting males in this age range could be super-spreaders of malaria parasites. The proportion of mosquitoes that fed on multiple humans ranged from 6% to 13% among villages. The patterns of host utilization observed here can amplify transmission and contribute to the persistence of malaria in PNG despite efforts to suppress it with insecticidal bed nets. Excessive feeding on males aged 15–30 years underscores the importance of targeted interventions focusing on this demographic group.

Detection of mixed infection of Plasmodium species in the Southern province of Rwanda. Case study: Ruhango, Bunyogombe and Kibilizi Health centres

Background: Malaria is a leading cause of mortality and morbidity in sub-Saharan Africa including Rwanda. Though the prevalence of malaria has been reduced due to the use of indoor residual sprayings and insecticide-treated bed nets, it is still a disease that kills many people annually. Many studies conducted revealed that in sub-Saharan Africa including Rwanda there is a high prevalence of Plasmodium falciparum. However, there is still a gap in the identification of the presence of mixed Plasmodium infection. This study was conducted to determine the overall prevalence of Plasmodium species as well as that of mixed plasmodium infection in Ruhango and Kibilizi Health centres.&#x0D; Methods: Descriptive cross-sectional study was conducted on 126 participants in Ruhango, Bunyogombe and Kibilizi health centres located in the southern province of Rwanda. The conventional sampling strategy was used for the selection of individuals who consented to participate in the study. Blood samples were used to detect Plasmodium species and the obtained data were analyzed using Microsoft excel and IBM SPSS version 21.&#x0D; Results: Among 126 participants presenting with signs and symptoms of malaria, the overall positive cases of Plasmodium species were 61(48.4%) and among the total positive cases 56 (44.5%) were infected with single Plasmodium species while 5 (4%) were infected with mixed Plasmodium species. Plasmodium falciparum was the most prevalent species infecting 49 (39%) participants while Plasmodium vivax was the least prevalent infection, detected in only 1(0.8%) participant.&#x0D; Conclusion: The study identified the significant prevalence of mixed-species of Plasmodium infection as well as the high prevalence of Plasmodium falciparum infection in the study population. These findings suggest that there is a need for continued monitoring of non-falciparum infection in this population and the introduction of species-specific RDTs that can be used for diagnostic purposes.

Insights into factors sustaining persistence of high malaria transmission in forested areas of sub-Saharan Africa: the case of Mvoua, South Cameroon

BackgroundIn Mvoua, a village situated in a forested area of Cameroon, recent studies have reported high prevalence of Plasmodium falciparum infection among the population. In order to understand factors that can sustain such a high malaria transmission, we investigated the biology of Anopheles vectors and its susceptibility to insecticides, as well as long-lasting insecticidal net (LLIN) coverage, use and bio-efficacy.MethodsA longitudinal entomological survey was conducted from July 2018 to April 2019. Adult mosquitoes were collected using the human landing catch (HLC) method and identified using morphological and molecular techniques. Anopheles gambiae (s.l.) larvae were sampled from several stagnant water pools throughout the village and reared to generate F1 adults. The presence of P. falciparum circumsporozoite antigen was detected in the heads and thoraces of mosquitoes collected as adults using an enzyme-linked immunosorbent assay. The insecticide susceptibility status of the local An. gambiae (s.l.) F1 population to the pyrethroid insecticides deltamethrin 0.5% and permethrin 0.75% was determined using World Health Organization-tube bioassays, while the frequency of the knockdown resistance (kdr) mutation was determined by PCR. Coverage, use and physical integrity of LLINs were assessed in households, then cone assays were used to test for their bio-efficacy on both the reference insecticide-susceptible Kisumu strain and on field F1 An. gambiae (s.l.)ResultsIn total, 110 Anopheles mosquitoes were collected, of which 59.1% were identified as Anopheles funestus (s.l.), 38.18% as An. gambiae (s.l.) and 2.72% as An. ziemanii. Anopheles funestus was the most abundant species except in the long rainy season, when An. gambiae (s.l.) predominated (65.8%). In the dry seasons, vectors were principally endophagous (76% of those collected indoors) while they tended to be exophagous (66% of those collected outdoors) in rainy seasons. High Plasmodium infection was observed in An. gambiae (s.l.) and An. funestus, with a circumsporozoitic rate of 14.29 and 10.77%, respectively. Anopheles gambiae (s.l.) was highly resistant to pyrethroid insecticides (mortality rates: 32% for permethrin and 5% for deltamethrin) and harbored the kdr-L1014F mutation at a high frequency (89.74%). Of the 80 households surveyed, only 47.69% had achieved universal coverage with LLNs. Around 70% of the LLINs sampled were in poor physical condition, with a proportionate hole index > 300. Of the ten LLNs tested, eight were effective against the An. gambiae reference insecticide-susceptible Kisumu strain, showing mortality rate of > 80%, while none of these LLINs were efficient against local An. gamabie (s.l.) populations (mortality rates < 11.5%).ConclusionA combination of elevated P. falciparum infection in Anopheles vector populations, insufficient coverage and loss of effectiveness of LLINs due to physical degradation, as well as high resistance to pyrethroid insecticides is responsible for the persistence of high malaria transmission in forested rural area of Mvoua, Cameroon.Graphical

Community Health Impacts of the Trident Copper Mine Project in Northwestern Zambia: Results from Repeated Cross-Sectional Surveys.

The application of a health impact assessment (HIA) for a large-scale copper mining project in rural Zambia triggered the long-term monitoring and evaluation of determinants of health and health outcomes in communities living in proximity to the mine. Three consecutive cross-sectional surveys were conducted at intervals of four years; thus, at baseline (2011), four (2015) and eight (2019) years into the project’s development. Using the same field and laboratory procedures, the surveys allowed for determining changes in health indicators at the household level, in young children (<5 years), school attendees (9–14 years) and women (15–49 years). Results were compared between communities considered impacted by the project and communities outside the project area (comparison communities). The prevalence of Plasmodium falciparum infection increased in both the impacted and comparison communities between 2011 and 2019 but remained consistently lower in the impacted communities. Stunting in children < 5 years and the prevalence of intestinal parasite infections in children aged 9–14 years mostly decreased. In women of reproductive age, selected health indicators (i.e., anaemia, syphilis, underweight and place of delivery) either remained stable or improved. Impacted communities generally showed better health outcomes than comparison communities, suggesting that the health interventions implemented by the project as a consequence of the HIA have mitigated potential negative effects and enhanced positive effects. Caution is indicated to avoid promotion of health inequalities within and beyond the project area.

Prevalence of Plasmodium falciparum Infection (Malaria) Among Pregnant Women Attending Primary Health Care in Wushishi

Plasmodium falciparum is the leading cause of malaria in pregnant women, a disease of public health importance especially in Nigeria where the infection is endemic. Hence, this study was conducted to ascertain the prevalent rate of Plasmodium falciparum infection among pregnant women attending antenatal in primary health care center, Wushishi Local Government, Niger state, Nigeria. 150 pregnant women were randomly selected and tested for P. falciparum using Plasmodium falciparum (05FK50) Rapid Diagnostic Test kit. The result obtained, revealed that 36 (24%) out of the 150 samples of the pregnant women were positive without any clinical manifestation of the infection. The result revealed that the prevalence rate was higher among women within 11-20 age group (43.8%) than those within 21-30 (17.4%) and 31 and above (9.0%). It was also observed from the study that prevalence rate was lower among women who use Insecticide Treated Net (6.5%) compared to those who does not (52.6%). Therefore the problem of Plasmodium falciparum infection in pregnant women should be prevented by the use of insecticide treated nets and effective case management with appropriate antimalarial drug during antenatal clinical visits.

Prevalence of Plasmodium falciparum in symptomatic and asymptomatic children in Minna, North Central Nigeria

The prevalence of Plasmodium falciparum in asymptomatic children and its association with symptomatic malaria cases was assessed in a cohort of children from Minna, Nigeria. A total of 220 children aged 6 months to 17 years were recruited from the community and healthcare facilities. Thick and thin films of the blood samples were prepared and the parasite density was determined using the thick film while the parasite species was identified using thin film. Overall, the prevalence of Plasmodium falciparum was 70% (153/220) out of which 28% (43/153) was observed in apparently healthy children from the community (asymptomatic) and 72% (110/148) from children with fever (symptomatic). The highest parasite prevalence was observed in children 6 to 11 years 30% (22/72) for asymptomatic infection; while symptomatic infection recorded 44% (65/110) from 6 months to 5 years of age. Females tends to show a greater prevalence of Plasmodium falciparum infection with 77% (20/26) and 78% (49/63) for both asymptomatic and symptomatic infections respectively. Parasitemia was, however, not significantly associated with fever (p>0.05). This study confirms that malaria remains a major cause of febrile illness during the early stages of childhood (<5 years). This may however, guide case definition for clinical trials of preventive tools, as well as provide definitions that may improve the precision of measurement of the burden of malaria. #These authors contributed equally to this work.

Challenges in Treatment for Fever among School-Age Children and Adults in Malawi.

Prompt and effective treatment is key to malaria control and prevention, as it reduces disease morbidity and mortality and minimizes the number of transmission reservoirs. Transmission reduction may be particularly important among school-age children (SAC, 5-15 years old), who have the highest prevalence of Plasmodium falciparum infection in southern Malawi. We hypothesized that one factor contributing to this difference in prevalence is that SAC are less likely to seek appropriate treatment for fever than children younger than 5 years. In this study, we assessed treatment-seeking behaviors of people of all ages between 2012 and 2014 in Malawi. During each of the five cross-sectional surveys, all members of ∼900 households reported on fever and treatment-seeking in the previous 2 weeks. Multilevel logistic regression was used to analyze predictors of whether febrile people sought treatment and whether they did so at formal (government/private clinics) or informal sources (primarily shops). Twenty-two percent of participants (3,579/16,621) reported fever, and 2,715 of those (75.9%) sought treatment. Seeking treatment exclusively from local shops remains a common practice, although use of recommended diagnostic testing and antimalarial drugs was infrequently reported there. Although SAC were not significantly less likely than children aged < 5 years to seek treatment, SAC and adults (age ≥ 16 years) were significantly less likely to use formal sources. Our results indicate that encouraging treatment at government/private clinics and increasing retail access to appropriate antimalarial testing and treatment, especially among SAC, could help remedy inadequate treatment of symptomatic disease and potentially reduce Plasmodium transmission in Malawi.

Impact evaluation of malaria control interventions on morbidity and all-cause child mortality in Mali, 2000\u20132012

BackgroundMajor investments have been made since 2001, with intensification of malaria control interventions after 2006. Interventions included free distribution of insecticide-treated nets (ITN) to pregnant women and children under 5 years old, the introduction of artemisinin combination therapy (ACT) for malaria treatment, and indoor residual spraying of insecticides. Funders include the Government of Mali, the Global Fund to Fight AIDS, Tuberculosis and Malaria, and the US President’s Malaria Initiative.MethodsData from nationally representative household surveys conducted from 2000 to 2015 was used to performed the trend analysis for malaria intervention coverage, prevalence of morbidities among children under 5 years old [parasitemia and severe anaemia (< 8 g/dl)], and all-cause mortality of children under 5 (ACCM). Prevalence of contextual factors likely to contribute to ACCM were also assessed. The impact of these interventions was assessed on malaria morbidity and mortality using a plausibility argument. With the assumption that malaria contributes significantly to under-five mortality in settings with high malaria transmission, associations between malaria control interventions and all-cause under-five mortality (ACCM) were assessed taking into account other contextual factors related to child survival.ResultsIntervention coverage improved significantly from 2006 to 2012. Household ownership of ITN increased from 49% in 2006 to 84% in 2012. ITN use also increased over the same period, from 26% in 2006 to 69% in 2012 among children under 5 and from 28% in 2006 to 73% in 2012 among pregnant women. The coverage of intermittent preventive treatment in pregnancy (IPTp) using two or more doses of SP increased from 10% in 2006 to 29% in 2012. In 2010, 23% of febrile children under 5 received ACT, as opposed to 19% in 2012. The prevalence of Plasmodium falciparum infection increased from 2010 (38.6%) to 2012 (51.6%), followed by a decrease in 2015 (35.8%). The prevalence of severe anaemia decreased from 2010 (26.3%) to 2012 (20.6%) and continued to decline in 2015 (19.9%). An impressive decline in ACCM was observed, from 225 in 1997–2001 to 192 in 2002–2006 and 95 in 2008–2012. Changes in contextual factors such as climate, socio-economic, nutrition, and coverage of maternal and child health interventions over the evaluation period did not favour reductions in ACCM, and are therefore unlikely to explain the observed results.ConclusionsTaken as a whole, the evidence supports the conclusion that malaria control interventions substantially contributed to the observed decline in ACCM in Mali from 2000 to 2012, even in the context of continued high prevalence of parasitaemia explained by contextual factors such as climate change and political instability.

Prevalence of Plasmodium falciparum infection among pregnant women at first antenatal visit in post-Ebola Monrovia, Liberia

BackgroundDisruption of malaria control strategies during the West African 2014–2016 Ebola epidemic led to an increase in malaria-attributable mortality. However, recent data on malaria infection in vulnerable groups, such as pregnant women, are lacking in this post-Ebola scenario. This cross-sectional study aimed to assess the prevalence of Plasmodium falciparum infection and of molecular markers of drug resistance among pregnant women attending antenatal care in Monrovia, capital of Liberia.MethodsFrom October 2016 to June 2017, all pregnant women attending their first antenatal care visit at the Saint Joseph’s Catholic Hospital, Monrovia, were invited to participate in the study. In addition to their routine antenatal care tests, capillary blood spotted onto filter papers were collected from all consenting participants to determine presence of P. falciparum by real-time quantitative PCR. Molecular markers of anti-malarial drug resistance were assessed through Sanger sequencing and quantitative PCR in specimens positive for P. falciparum analysis.ResultsOf the 195 women participants, 24 (12.3%) were P. falciparum-positive by qPCR. Infected women tended to be more commonly primigravidae and younger than uninfected ones. Parasite densities were higher in primigravidae. Fever was more frequently detected among the infected women. No statistically significant association between P. falciparum infection and haemoglobin levels or insecticide-treated net use was found. While high prevalence of genetic polymorphisms associated with chloroquine and amodiaquine resistance were detected, no molecular markers of artemisinin resistance were observed.ConclusionPlasmodium falciparum infections are expected to occur in at least one in every eight women attending first ANC at private clinics in Monrovia and outside the peak of the rainy season. Young primigravidae are at increased risk of P. falciparum infection. Molecular analyses did not provide evidence of resistance to artemisinins among the P. falciparum isolates tested. Further epidemiological studies involving pregnant women are necessary to describe the risk of malaria in this highly susceptible group outside Monrovia, as well as to closely monitor the emergence of resistance to anti-malarials, as recommended by the Liberian National Malaria Control Programme.

Reduction of malaria prevalence after introduction of artemisinin-combination-therapy in Mbeya Region, Tanzania: results from a cohort study with 6773 participants

BackgroundA marked decline in malaria morbidity and mortality has been reported after the introduction of artemisinin-based combination therapy (ACT) in high malaria prevalence countries in Africa. Data on the impact of ACT and on the prevalence of malaria has so far been scarce for Southwest Tanzania.MethodsBetween 2005 and 2011, a large general population cohort in the Mbeya Region in the south-west of Tanzania has been surveyed within the EMINI-study (Evaluation and Monitoring of the Impact of New Interventions). Participants were examined once per year, including rapid diagnostic testing for malaria. ACT was introduced in the region according to national guidelines in the time period 2006/2007, replacing sulfadoxine/pyrimethamine as first-line therapy. In four study sites, 6773 individuals who participated in the first two of three consecutive survey visits in the period from 2006 to 2009 were included in this analysis. The prevalence of Plasmodium infection prior to and after the introduction of ACT was compared by logistic regression, with consideration of climatic variability, age, sex, socio-economic status and bed net use as potential confounders.ResultsA significant reduction over time in the prevalence of Plasmodium falciparum infection from 2.5 to 0.3% was shown across the four study sites. The decline was not explained by other factors included in the analysis, therefore, the decline over time most likely reflects the impact of introduction of ACT in the study area.ConclusionsThe longitudinal study showed a significant and relevant decline in the prevalence of P. falciparum infection after introduction of ACT, which could not be explained by potential confounders. The data suggests that artemisinin-based combinations are not only an effective instrument for reduction of immediate morbidity and mortality, but also for reduction of transmission rates.