scholarly journals Combination of Serological, Antigen Detection, and DNA Data for Plasmodium falciparum Provides Robust Geospatial Estimates for Malaria Transmission in Haiti

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adan Oviedo ◽  
Alaine Knipes ◽  
Caitlin Worrell ◽  
LeAnne M. Fox ◽  
Luccene Desir ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
Spatial Epidemiology ◽  
Point Of Care ◽  
Igg Antibodies ◽  
Malaria Epidemiology ◽  
Different Types ◽  
Malaria Antigen ◽  
Study Sites ◽  
National Prevalence

Abstract Microscopy is the gold standard for malaria epidemiology, but laboratory and point-of-care (POC) tests detecting parasite antigen, DNA, and human antibodies against malaria have expanded this capacity. The island nation of Haiti is endemic for Plasmodium falciparum (Pf) malaria, though at a low national prevalence and heterogenous geospatial distribution. In 2015 and 2016, serosurveys were performed of children (ages 6–7 years) sampled in schools in Saut d’Eau commune (n = 1,230) and Grand Anse department (n = 1,664) of Haiti. Children received malaria antigen rapid diagnostic test and provided a filter paper blood sample for further laboratory analysis of the Pf histidine-rich protein 2 (HRP2) antigen, Pf DNA, and anti-Pf IgG antibodies. Prevalence of Pf infection ranged from 0.0–16.7% in 53 Saut d’Eau schools, and 0.0–23.8% in 56 Grand Anse schools. Anti-Pf antibody carriage exceeded 80% of students in some schools from both study sites. Geospatial prediction ellipses were created to indicate clustering of positive tests within the survey areas and overlay of all prediction ellipses for the different types of data revealed regions with high likelihood of active and ongoing Pf malaria transmission. The geospatial utilization of different types of Pf data can provide high confidence for spatial epidemiology of the parasite.

scholarly journals Genetic Architecture and Dynamics of PfKelch13’s Propeller Domain in Plasmodium Falciparum Clinical Isolates Collected in Senegal.

2021 ◽  
Author(s):  
Mariama Pouye ◽  
Gora Diop ◽  
celine Derbois ◽  
Babacar Mbengue ◽  
oumar Ka ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
Artemisinin Resistance ◽  
Clinical Isolates ◽  
Health Concern ◽  
Gene Marker ◽  
Resistance Mutations ◽  
Malaria Epidemiology ◽  
Strategic Plans ◽  
Transmission Area

Abstract Plasmodium resistance to Artemisinin Combination-based Therapies (ACT) in Southeast Asia is a major public health concern that is sporadically appearing in Africa. Senegal has shifted from malaria control to elimination plans. Given notable progresses obtained through robust strategic plans, it is still crucial to assess genetic variability of the Plasmodium falciparum artemisinin resistance gene marker Kelch13 (PfKelch13) in circulating field isolates. We here report an analysis of PfKelch13-propeller polymorphism in clinical isolates collected nine years after ACT introduction in five Senegalese regions with different malaria transmission settings. Sequencing of PfKelch13-propeller domain from 280 clinical isolates reveals that 16% (45/280) of the parasite population harbored variants. Dynamics of PfKelch13 variants reveals emerging, persistent but also disappearing mutations over time. In addition to the malaria epidemiology, our survey also shows the dynamics of PfKelch13 variants in different malaria transmission settings in Senegal. Despite the absence of PfKelch13 associated artemisinin resistance mutations, a shift from 86% to 68% of PfKelch13WT was observed when comparing parasites collected prior vs. post ACT intensive usage in Dakar a low malaria transmission area. All together, our data confirms the need to closely monitor PfKelch13 polymorphism to anticipate and or prevent emergence of P. falciparum resistance in Senegal.

scholarly journals Low Prevalence of Antibodies to Preerythrocytic but Not Blood-Stage Plasmodium falciparum Antigens in an Area of Unstable Malaria Transmission Compared to Prevalence in an Area of Stable Malaria Transmission

2008 ◽  
Vol 76 (12) ◽  
pp. 5721-5728 ◽  
Author(s):  
Gregory S. Noland ◽  
Brett Hendel-Paterson ◽  
Xinan M. Min ◽  
Ann M. Moormann ◽  
John M. Vulule ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
Merozoite Surface Protein ◽  
Blood Stage ◽  
Igg Antibodies ◽  
Age Related ◽  
Transmission Area ◽  
High Level ◽  
Stable Transmission ◽  
Unstable Transmission

ABSTRACT In areas where levels of transmission of Plasmodium falciparum are high and stable, the age-related acquisition of high-level immunoglobulin G (IgG) antibodies to preerythrocytic circumsporozoite protein (CSP) and liver-stage antigen 1 (LSA-1) has been associated with protection from clinical malaria. In contrast, age-related protection from malaria develops slowly or not at all in residents of epidemic-prone areas with unstable low levels of malaria transmission. We hypothesized that this suboptimal clinical and parasitological immunity may in part be due to reduced antibodies to CSP or LSA-1 and/or vaccine candidate blood-stage antigens. Frequencies and levels of IgG antibodies to CSP, LSA-1, thrombospondin-related adhesive protein (TRAP), apical membrane antigen 1 (AMA-1), erythrocyte binding antigen 175 (EBA-175), and merozoite surface protein 1 (MSP-1) were compared in 243 Kenyans living in a highland area of unstable transmission and 210 residents of a nearby lowland area of stable transmission. Levels of antibodies to CSP, LSA-1, TRAP, and AMA-1 in the oldest age group (>40 years) in the unstable transmission area were lower than or similar to those of children 2 to 6 years old in the stable transmission area. Only 3.3% of individuals in the unstable transmission area had high levels of IgG (>2 arbitrary units) to both CSP and LSA-1, compared to 43.3% of individuals in the stable transmission area. In contrast, antibody levels to and frequencies of MSP-1 and EBA-175 were similar in adults in areas of stable and unstable malaria transmission. Suboptimal immunity to malaria in areas of unstable malaria transmission may relate in part to infrequent high-level antibodies to preerythrocytic antigens and AMA-1.

scholarly journals PO 8418 NEW MALARIA EPIDEMIOLOGY IN COASTAL LAGOON OF BENIN: PLASMODIUM INFECTION IN ANOPHELES MELAS

2019 ◽  
Vol 4 (Suppl 3) ◽  
pp. A35.1-A35
Author(s):  
Claudiane Adigbonon ◽  
Benoît S Assogba ◽  
Luc S Djogbenou
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Vivax ◽  
Malaria Transmission ◽  
Coastal Lagoon ◽  
Plasmodium Malariae ◽  
Dry Season ◽  
Anopheles Coluzzii ◽  
Plasmodium Ovale ◽  
Malaria Epidemiology ◽  
Tropical Areas

IntroductionMalaria is a worldwide disease affecting many people particularly in the tropical and sub-tropical areas. It is caused by Plasmodium parasites and essentially transmitted by female mosquitoes belonging to the Anopheles genus. Our understanding of the infectivity of these vectors to Plasmodium is necessary to design sustainable strategies for their control. This aspect remains unknown in the coastal and lagoon area of Benin where Anopheles melas and Anopheles coluzzii are sympatric. This study aims to investigate the infectivity of these two vectors to Plasmodium to understand their role in malaria transmission in southern Benin.MethodsInsecticide spray catch technique was used to collect females in 80 houses randomly selected in our study site. Three hundred and twenty (320) females were identified using PCR–species technique, Plasmodium infection was determined by the TaqMan method during the dry season. This assay detects all four malaria-causing species and discriminates Plasmodium falciparum from Plasmodium ovale, Plasmodium vivax and Plasmodium malariae (OVM).ResultsDuring the dry season, the sporozoïte rates were 0.2% and 0.3% for Anopheles melas and Anopheles coluzzii, respectively. However, we observed that positivity to the OVM (one of Plasmodium ovale, Plasmodium vivax and Plasmodium malariae species) was significantly higher in Anopheles melas (95%) than in Anopheles coluzzii (33.33%) (Chi-sq=15 857, df=1, p<0.001). These results indicated that Anopheles melas is more infected by one of the species Plasmodium ovale, Plamodium vivax and Plasmodium malariae than by Plasmodium falciparum, contrarily to Anopheles coluzzii.ConclusionThese findings reinforce the debate on the role of Anopheles melas in malaria transmission in coastal lagoon areas of Benin.

scholarly journals Effect of seasonal malaria chemoprevention plus azithromycin on Plasmodium falciparum transmission: gametocyte infectivity and mosquito fitness

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Koudraogo Bienvenue Yaméogo ◽  
Rakiswendé Serge Yerbanga ◽  
Seydou Bienvenu Ouattara ◽  
Franck A. Yao ◽  
Thierry Lefèvre ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Transmission ◽  
Life History Traits ◽  
Controlled Trial ◽  
Double Blind ◽  
Membrane Feeding ◽  
Seasonal Malaria Chemoprevention ◽  
Negative Effect ◽  
Transmission Period ◽  
Membrane Feeding Assay

Abstract Background Seasonal malaria chemoprevention (SMC) consists of administration of sulfadoxine-pyrimethamine (SP) + amodiaquine (AQ) at monthly intervals to children during the malaria transmission period. Whether the addition of azithromycin (AZ) to SMC could potentiate the benefit of the intervention was tested through a double-blind, randomized, placebo-controlled trial. The effect of SMC and the addition of AZ, on malaria transmission and on the life history traits of Anopheles gambiae mosquitoes have been investigated. Methods The study included 438 children randomly selected from among participants in the SMC + AZ trial and 198 children from the same area who did not receive chemoprevention. For each participant in the SMC + AZ trial, blood was collected 14 to 21 days post treatment, examined for the presence of malaria sexual and asexual stages and provided as a blood meal to An. gambiae females using a direct membrane-feeding assay. Results The SMC treatment, with or without AZ, significantly reduced the prevalence of asexual Plasmodium falciparum (LRT X22 = 69, P < 0.0001) and the gametocyte prevalence (LRT X22 = 54, P < 0.0001). In addition, the proportion of infectious feeds (LRT X22 = 61, P < 0.0001) and the prevalence of oocysts among exposed mosquitoes (LRT X22 = 22.8, P < 0.001) was reduced when mosquitoes were fed on blood from treated children compared to untreated controls. The addition of AZ to SPAQ was associated with an increased proportion of infectious feeds (LRT X21 = 5.2, P = 0.02), suggesting a significant effect of AZ on gametocyte infectivity. There was a slight negative effect of SPAQ and SPAQ + AZ on mosquito survival compared to mosquitoes fed with blood from control children (LRTX22 = 330, P < 0.0001). Conclusion This study demonstrates that SMC may contribute to a reduction in human to mosquito transmission of P. falciparum, and the reduced mosquito longevity observed for females fed on treated blood may increase the benefit of this intervention in control of malaria. The addition of AZ to SPAQ in SMC appeared to enhance the infectivity of gametocytes providing further evidence that this combination is not an appropriate intervention.

scholarly journals Effect of naturally occurring Wolbachia in Anopheles gambiae s.l. mosquitoes from Mali on Plasmodium falciparum malaria transmission

2017 ◽  
Vol 114 (47) ◽  
pp. 12566-12571 ◽  
Author(s):  
Fabio M. Gomes ◽  
Bretta L. Hixson ◽  
Miles D. W. Tyner ◽  
Jose Luis Ramirez ◽  
Gaspar E. Canepa ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Anopheles Gambiae ◽  
Malaria Transmission ◽  
Deleterious Effect ◽  
Plasmodium Falciparum Malaria ◽  
Anopheles Coluzzii ◽  
Naturally Occurring ◽  
Anopheles Gambiae S.L ◽  
Cat Fleas ◽  
Sporozoite Infection

A naturally occurring Wolbachia strain (wAnga-Mali) was identified in mosquitoes of the Anopheles gambiae complex collected in the Malian villages of Dangassa and Kenieroba. Phylogenetic analysis of the nucleotide sequence of two 16S rRNA regions showed that wAnga-Mali clusters with Wolbachia strains from supergroup A and has the highest homology to a Wolbachia strain isolated from cat fleas (Ctenocephalides). wAnga-Mali is different from two Wolbachia strains previously reported in A. gambiae from Burkina Faso (wAnga_VK5_STP and wAnga_VK5_3.1a). Quantitative analysis of Wolbachia and Plasmodium sporozoite infection in field-collected mosquitoes indicates that the prevalence and intensity of Plasmodium falciparum sporozoite infection is significantly lower in Wolbachia-infected females. The presence of Wolbachia in females from a laboratory Anopheles coluzzii (A. gambiae, M form) colony experimentally infected with P. falciparum (NF54 strain) gametocyte cultures slightly enhanced oocyst infection. However, Wolbachia infection significantly reduced the prevalence and intensity of sporozoite infection, as observed in the field. This indicates that wAnga-Mali infection does not limit early stages of Plasmodium infection in the mosquito, but it has a strong deleterious effect on sporozoites and reduces malaria transmission.

scholarly journals The epidemiology and detectability of asymptomatic Plasmodium vivax and Plasmodium falciparum infections in low, moderate and high transmission settings in Ethiopia

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Elifaged Hailemeskel ◽  
Surafel K Tebeje ◽  
Sinknesh W. Behaksra ◽  
Girma Shumie ◽  
Getasew Shitaye ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Vivax ◽  
Age Groups ◽  
Diagnostic Tools ◽  
Asymptomatic Malaria ◽  
Rapid Diagnostics ◽  
Cross Sectional ◽  
Low Transmission ◽  
High Transmission ◽  
Study Sites

Abstract Background As countries move to malaria elimination, detecting and targeting asymptomatic malaria infections might be needed. Here, the epidemiology and detectability of asymptomatic Plasmodium falciparum and Plasmodium vivax infections were investigated in different transmission settings in Ethiopia. Method: A total of 1093 dried blood spot (DBS) samples were collected from afebrile and apparently healthy individuals across ten study sites in Ethiopia from 2016 to 2020. Of these, 862 were from community and 231 from school based cross-sectional surveys. Malaria infection status was determined by microscopy or rapid diagnostics tests (RDT) and 18S rRNA-based nested PCR (nPCR). The annual parasite index (API) was used to classify endemicity as low (API > 0 and < 5), moderate (API ≥ 5 and < 100) and high transmission (API ≥ 100) and detectability of infections was assessed in these settings. Results In community surveys, the overall prevalence of asymptomatic Plasmodium infections by microscopy/RDT, nPCR and all methods combined was 12.2% (105/860), 21.6% (183/846) and 24.1% (208/862), respectively. The proportion of nPCR positive infections that was detectable by microscopy/RDT was 48.7% (73/150) for P. falciparum and 4.6% (2/44) for P. vivax. Compared to low transmission settings, the likelihood of detecting infections by microscopy/RDT was increased in moderate (Adjusted odds ratio [AOR]: 3.4; 95% confidence interval [95% CI] 1.6–7.2, P = 0.002) and high endemic settings (AOR = 5.1; 95% CI 2.6–9.9, P < 0.001). After adjustment for site and correlation between observations from the same survey, the likelihood of detecting asymptomatic infections by microscopy/RDT (AOR per year increase = 0.95, 95% CI 0.9–1.0, P = 0.013) declined with age. Conclusions Conventional diagnostics missed nearly half of the asymptomatic Plasmodium reservoir detected by nPCR. The detectability of infections was particularly low in older age groups and low transmission settings. These findings highlight the need for sensitive diagnostic tools to detect the entire parasite reservoir and potential infection transmitters.

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