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Quantitative diagnosis of glucose-6-phosphate dehydrogenase (G6PD) deficiency is essential for the safe administration of 8-aminoquinoline based radical cure for the treatment of Plasmodium vivax infections. Here, we present the PreQuine Platform (IVDS, USA), a quantitative biosensor that uses a dual-analyte assay for the simultaneous measurement of Hemoglobin (Hgb) levels and G6PD enzyme activity within the same sample. The platform relies on a downloadable mobile application. The device requires 10μl of whole blood and works with a reflectance-based meter. Comparing the G6PD measurement normalized by Hgb of 12 samples from the PreQuine Platform with reference measurements methods (spectrophotometry, Pointe Scientific, USA and hemoglobin meter, HemoCue, Sweden) showed a positive and significant agreement with a slope of 1.0091 and an intercept of -0.0379 under laboratory conditions. Next steps will be to conduct field trials in Bangladesh, Cambodia, and the USA to assess diagnostic performance, user friendliness and acceptance. [ABSTRACT FROM AUTHOR]

Mayaro virus (MAYV) is a mosquito-borne Alphavirus that is widespread in South America. MAYV infection often presents with non-specific febrile symptoms but may progress to debilitating chronic arthritis or arthralgia. Despite the pandemic threat of MAYV, its true distribution remains unknown. The objective of this study was to clarify the geographic distribution of MAYV using an established risk mapping framework. This consisted of generating evidence consensus scores for MAYV presence, modeling the potential distribution of MAYV in select countries across Central and South America, and estimating the population residing in areas suitable for MAYV transmission. We compiled a georeferenced compendium of MAYV occurrence in humans, animals, and arthropods. Based on an established evidence consensus framework, we integrated multiple information sources to assess the total evidence supporting ongoing transmission of MAYV within each country in our study region. We then developed high resolution maps of the disease's estimated distribution using a boosted regression tree approach. Models were developed using nine climatic and environmental covariates that are related to the MAYV transmission cycle. Using the output of our boosted regression tree models, we estimated the total population living in regions suitable for MAYV transmission. The evidence consensus scores revealed high or very high evidence of MAYV transmission in several countries including Brazil (especially the states of Mato Grosso and Goiás), Venezuela, Peru, Trinidad and Tobago, and French Guiana. According to the boosted regression tree models, a substantial region of South America is suitable for MAYV transmission, including north and central Brazil, French Guiana, and Suriname. Some regions (e.g., Guyana) with only moderate evidence of known transmission were identified as highly suitable for MAYV. We estimate that approximately 58.9 million people (95% CI: 21.4–100.4) in Central and South America live in areas that may be suitable for MAYV transmission, including 46.2 million people (95% CI: 17.6–68.9) in Brazil. Our results may assist in prioritizing high-risk areas for vector control, human disease surveillance and ecological studies. Author summary: We used a comprehensive, georeferenced compendium of Mayaro virus (MAYV) occurrence to model the suitability for MAYV in Central and South America. Our boosted regression tree model incorporated 195 MAYV occurrence locations and 9 gridded environmental covariates to generate a 5 x 5 km continuous surface of MAYV suitability across Central and South America. Using this distribution model, we estimated the total population residing in areas that are suitable for MAYV transmission. Furthermore, we developed evidence consensus scores for each country in our study region that synthesized a variety of sources to assess the overall evidence of known MAYV transmission. Our study provides a contemporary estimate of MAYV distribution using a well-established disease mapping framework. This information provides an evidence base that can guide disease surveillance (including human cases and ecological studies) and vector control efforts in Central and South America. This is especially useful in regions with high predicted MAYV suitability but only moderate evidence of current MAYV transmission (e.g., Guyana and Suriname). [ABSTRACT FROM AUTHOR]

Mayaro Virus (MAYV) is an emerging health threat in the Americas that can cause febrile illness as well as debilitating arthralgia or arthritis. To better understand the geographic distribution of MAYV risk, we developed a georeferenced database of MAYV occurrence based on peer-reviewed literature and unpublished reports. Here we present this compendium, which includes both point and polygon locations linked to occurrence data documented from its discovery in 1954 until 2022. We describe all methods used to develop the database including data collection, georeferencing, management and quality-control. We also describe a customized grading system used to assess the quality of each study included in our review. The result is a comprehensive, evidence-graded database of confirmed MAYV occurrence in humans, non-human animals, and arthropods to-date, containing 262 geo-positioned occurrences in total. This database - which can be updated over time - may be useful for local spill-over risk assessment, epidemiological modelling to understand key transmission dynamics and drivers of MAYV spread, as well as identification of major surveillance gaps. [ABSTRACT FROM AUTHOR]

Improving our understanding of Mayaro virus (MAYV) ecology is critical to guide surveillance and risk assessment. We conducted a PRISMA-adherent systematic review of the published and grey literature to identify potential arthropod vectors and non-human animal reservoirs of MAYV. We searched PubMed/MEDLINE, Embase, Web of Science, SciELO and grey-literature sources including PAHO databases and dissertation repositories. Studies were included if they assessed MAYV virological/immunological measured occurrence in field-caught, domestic, or sentinel animals or in field-caught arthropods. We conducted an animal seroprevalence meta-analysis using a random effects model. We compiled granular georeferenced maps of non-human MAYV occurrence and graded the quality of the studies using a customized framework. Overall, 57 studies were eligible out of 1523 screened, published between the years 1961 and 2020. Seventeen studies reported MAYV positivity in wild mammals, birds, or reptiles and five studies reported MAYV positivity in domestic animals. MAYV positivity was reported in 12 orders of wild-caught vertebrates, most frequently in the orders Charadriiformes and Primate. Sixteen studies detected MAYV in wild-caught mosquito genera including Haemagogus, Aedes, Culex, Psorophora, Coquillettidia, and Sabethes. Vertebrate animals or arthropods with MAYV were detected in Brazil, Panama, Peru, French Guiana, Colombia, Trinidad, Venezuela, Argentina, and Paraguay. Among non-human vertebrates, the Primate order had the highest pooled seroprevalence at 13.1% (95% CI: 4.3–25.1%). From the three most studied primate genera we found the highest seroprevalence was in Alouatta (32.2%, 95% CI: 0.0–79.2%), followed by Callithrix (17.8%, 95% CI: 8.6–28.5%), and Cebus/Sapajus (3.7%, 95% CI: 0.0–11.1%). We further found that MAYV occurs in a wide range of vectors beyond Haemagogus spp. The quality of evidence behind these findings was variable and prompts calls for standardization of reporting of arbovirus occurrence. These findings support further risk emergence prediction, guide field surveillance efforts, and prompt further in-vivo studies to better define the ecological drivers of MAYV maintenance and potential for emergence. Author summary: Mayaro virus (MAYV) is an emerging tropical public health threat in the Americas. We conducted a georeferenced, quality-graded systematic review to evaluate the current evidence regarding MAYV occurrence in non-human vertebrates and arthropods. Overall, 57 studies were eligible out of 1523 screened, published between the years 1961 and 2020. Seventeen studies reported MAYV positivity in wild mammals, birds, or reptiles and five studies reported MAYV positivity in domestic animals. MAYV positivity was reported in 12 orders of wild-caught vertebrates, most frequently in the orders Charadriiformes and Primate. Our systematic review identified 12 orders of wild-caught vertebrates and seven mosquito genera with evidence of MAYV occurrence. Primates had the highest pooled MAYV seroprevalence according to a seroprevalence meta-analysis. The graded quality of evidence behind these findings was variable and prompts calls for standardization of reporting of MAYV and perhaps other emerging arbovirus occurrence in animals and vectors. This study provides important information for public health authorities and disease ecologists concerned with the growing threat of MAYV in Latin America. Our analysis provides a foundation for future laboratory and field studies focused on the MAYV transmission cycle. [ABSTRACT FROM AUTHOR]

Madariaga virus (MADV), also known as South American eastern equine encephalitis virus, has been identified in animals and humans in South and Central America, but not previously in Hispaniola or the northern Caribbean. MADV was isolated from virus cultures of plasma from an 8-year-old child in a school cohort in the Gressier/Leogane region of Haiti, who was seen in April, 2015, with acute febrile illness (AFI). The virus was subsequently cultured from an additional seven AFI case patients from this same cohort in February, April, and May 2016. Symptoms most closely resembled those seen with confirmed dengue virus infection. Sequence data were available for four isolates: all were within the same clade, with phylogenetic and molecular clock data suggesting recent introduction of the virus into Haiti from Panama sometime in the period from October 2012-January 2015. Our data document the movement of MADV into Haiti, and raise questions about the potential for further spread in the Caribbean or North America. [ABSTRACT FROM AUTHOR]

As part of on-going arboviral surveillance activity in a semi-rural region in Haiti, Chikungunya virus (CHIKV)-positive mosquito pools were identified in 2014 (the peak of the Caribbean Asian-clade epidemic), and again in 2016 by RT-PCR. In 2014, CHIKV was only identified in Aedes aegypti (11 positive pools/124 screened). In contrast, in sampling in 2016, CHIKV was not identified in Ae. aegypti, but, rather, in (a) a female Aedes albopictus pool, and (b) a female Culex quinquefasciatus pool. Genomic sequence analyses indicated that the CHIKV viruses in the 2016 mosquito pools were from the East-Central-South African (ECSA) lineage, rather than the Asian lineage. In phylogenetic studies, these ECSA lineage strains form a new ECSA subgroup (subgroup IIa) together with Brazilian ECSA lineage strains from an isolated human outbreak in 2014, and a mosquito pool in 2016. Additional analyses date the most recent common ancestor of the ECSA IIa subgroup around May 2007, and the 2016 Haitian CHIKV genomes around December 2015. Known CHIKV mutations associated with improved Ae. albopictus vector competence were not identified. Isolation of this newly identified lineage from Ae. albopictus is of concern, as this vector has a broader geographic range than Ae. aegypti, especially in temperate areas of North America, and stresses the importance for continued vector surveillance. [ABSTRACT FROM AUTHOR]

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Background: Haiti has a set a target of eliminating malaria by 2020. However, information on malaria vector research in Haiti is not well known. This paper presents results from a systematic review of the literature on malaria vector research, bionomics and control in Haiti. Methods: A systematic search of literature published in French, Spanish and English languages was conducted in 2015 using Pubmed (MEDLINE), Google Scholar, EMBASE, JSTOR WHOLIS and Web of Science databases as well other grey literature sources such as USAID, and PAHO. The following search terms were used: malaria, Haiti, Anopheles, and vector control. Results: A total of 132 references were identified with 40 high quality references deemed relevant and included in this review. Six references dealt with mosquito distribution, seven with larval mosquito ecology, 16 with adult mosquito ecology, three with entomological indicators of malaria transmission, eight with insecticide resistance, one with sero-epidemiology and 16 with vector control. In the last 15 years (2000-2015), there have only been four published papers and three-scientific meeting abstracts on entomology for malaria in Haiti. Overall, the general literature on malaria vector research in Haiti is limited and dated. Discussion: Entomological information generated from past studies in Haiti will contribute to the development of strategies to achieve malaria elimination on Hispaniola. However it is of paramount importance that malaria vector research in Haiti is updated to inform decision-making for vector control strategies in support of malaria elimination. [ABSTRACT FROM AUTHOR]

Background: Zika virus (ZIKV), first isolated in Uganda in 1947, is currently spreading rapidly through South America and the Caribbean. In Brazil, infection has been linked with microcephaly and other serious complications, leading to declaration of a public health emergency of international concern; however, there currently are only limited data on the virus (and its possible sources and manifestations) in the Caribbean. Methods: From May, 2014-February, 2015, in conjunction with studies of chikungunya (CHIKV) and dengue (DENV) virus infections, blood samples were collected from children in the Gressier/Leogane region of Haiti who presented to a school clinic with undifferentiated febrile illness. Samples were initially screened by RT-PCR for CHIKV and DENV, with samples negative in these assays further screened by viral culture. Findings: Of 177 samples screened, three were positive for ZIKV, confirmed by viral sequencing; DENV-1 was also identified in culture from one of the three positive case patients. Patients were from two different schools and 3 different towns, with all three cases occurring within a single week, consistent with the occurrence of an outbreak in the region. Phylogenetic analysis of known full genome viral sequences demonstrated a close relationship with ZIKV from Brazil; additional analysis of the NS5 gene, for which more sequences are currently available, showed the Haitian strains clustering within a monophyletic clade distinct from Brazilian, Puerto Rican and Guatemalan sequences, with all part of a larger clade including isolates from Easter Island. Phylogeography also clarified that at least three major African sub-lineages exist, and confirmed that the South American epidemic is most likely to have originated from an initial ZIKV introduction from French Polynesia into Easter Island, and then to the remainder of the Americas. Conclusions: ZIKV epidemics in South America, as well as in Africa, show complex dissemination patterns. The virus appears to have been circulating in Haiti prior to the first reported cases in Brazil. Factors contributing to transmission and the possible linkage of this early Haitian outbreak with microcephaly remain to be determined. [ABSTRACT FROM AUTHOR]

Background: Public health measures are poised for transition from malaria control to malaria elimination on the island of Hispaniola. Assessment of the reservoir of asymptomatic infections from which acute malaria cases may derive is critical to plan and evaluate elimination efforts. Current field technology is ill suited for detecting submicroscopic infections, thus highly sensitive survey methods capable of detecting virtually all infections are needed. In this study the prevalence of infection with Plasmodium falciparum was determined in patients seeking medical care primarily for non-febrile conditions in six departments in Haiti using a newly designed qRT-PCR-based assay. Methods: Three different methods of parasite detection were compared to assess their utility in approximating the prevalence of P. falciparum infections in the population: malaria rapid diagnostic test (RDT) designed to detect histidinerich protein 2 (HRP2), thick smear microscopy, and a quantitative reverse transcription polymerase chain reaction (qRTPCR) assay based upon the small sub-unit ribosomal RNA. The limit of detection of the qRT-PCR assay utilized was 0.0003 parasite/μL of blood. Venous blood was obtained from a total of 563 subjects from six departments in Haiti, all of whom were seeking medical attention without complaints consistent with malaria. Each subject was questioned for knowledge and behaviour using demographic and epidemiological survey to identify risk factors for disease transmission. Results: Among the 563 samples tested, ten and 16 were found positive for malaria by RDT and microscopy, respectively. Using the qRT-PCR test to assess the infection status of these subjects, an additional 92 were identified for a total of 108. Based upon the qRT-PCR assay results, a wide variation in prevalence of infection in asymptomatic subjects was seen between geographic locations ranging from 4-41 %. The prevalence of infection was highest in the Grand Anse, Nord and Sud-Est Departments, and demographic data from questionnaires provide evidence for focal disease transmission. Conclusions: The qRT-PCR assay is sufficiently sensitive to identify an unexpectedly large number of asymptomatic, submicroscopic infections. Identifying and clearing these infections presents a significant challenge to both control and elimination efforts, but the qRT-PCR assay offers a reliable method to identify them. [ABSTRACT FROM AUTHOR]

Spondweni virus (SPONV) and Zika virus cause similar diseases in humans. We detected SPONV outside of Africa from a pool of Culex mosquitoes collected in Haiti in 2016. This finding raises questions about the role of SPONV as a human pathogen in Haiti and other Caribbean countries. [ABSTRACT FROM AUTHOR]

Hispaniola, comprising Haiti and the Dominican Republic, has been identified as a candidate for malaria elimination. However, incomplete surveillance data in Haiti hamper efforts to assess the impact of ongoing malaria control interventions. Characteristics of the genetic diversity of Plasmodium falciparum populations can be used to assess parasite transmission, which is information vital to evaluating malaria elimination efforts. Here we characterize the genetic diversity of P. falciparum samples collected from patients at seven sites in Haiti using 12 microsatellite markers previously employed in population genetic analyses of global P. falciparum populations. We measured multiplicity of infections, level of genetic diversity, degree of population geographic substructure, and linkage disequilibrium (defined as non-random association of alleles from different loci). For low transmission populations like Haiti, we expect to see few multiple infections, low levels of genetic diversity, high degree of population structure, and high linkage disequilibrium. In Haiti, we found low levels of multiple infections (12.9%), moderate to high levels of genetic diversity (mean number of alleles per locus = 4.9, heterozygosity = 0.61), low levels of population structure (highest pairwise Fst = 0.09 and no clustering in principal components analysis), and moderate linkage disequilibrium (ISA = 0.05, P<0.0001). In addition, population bottleneck analysis revealed no evidence for a reduction in the P. falciparum population size in Haiti. We conclude that the high level of genetic diversity and lack of evidence for a population bottleneck may suggest that Haiti’s P. falciparum population has been stable and discuss the implications of our results for understanding the impact of malaria control interventions. We also discuss the relevance of parasite population history and other host and vector factors when assessing transmission intensity from genetic diversity data. [ABSTRACT FROM AUTHOR]

Haiti and the Dominican Republic, which share the island of Hispaniola, are the last locations in the Caribbean where malaria still persists. Malaria is an important public health concern in Haiti with 17,094 reported cases in 2014. Further, on January 12, 2010, a record earthquake devastated densely populated areas in Haiti including many healthcare and laboratory facilities. Weakened infrastructure provided fertile reservoirs for uncontrolled transmission of infectious pathogens. This situation results in unique challenges for malaria epidemiology and elimination efforts. To help Haiti achieve its malaria elimination goals by year 2020, the Laboratoire National de Santé Publique and Henry Ford Health System, in close collaboration with the Direction d'Épidémiologie, de Laboratoire et de Recherches and the Programme National de Contrôle de la Malaria, hosted a scientific meeting on 'Elimination Strategies for Malaria in Haiti' on January 29-30, 2015 at the National Laboratory in Port-au-Prince, Haiti. The meeting brought together laboratory personnel, researchers, clinicians, academics, public health professionals, and other stakeholders to discuss main stakes and perspectives on malaria elimination. Several themes and recommendations emerged during discussions at this meeting. First, more information and research on malaria transmission in Haiti are needed including information from active surveillance of cases and vectors. Second, many healthcare personnel need additional training and critical resources on how to properly identify malaria cases so as to improve accurate and timely case reporting. Third, it is necessary to continue studies genotyping strains of Plasmodium falciparum in different sites with active transmission to evaluate for drug resistance and impacts on health. Fourth, elimination strategies outlined in this report will continue to incorporate use of primaquine in addition to chloroquine and active surveillance of cases. Elimination of malaria in Haiti will require collaborative multidisciplinary approaches, sound strategic planning, and strong ownership of strategies by the Haiti Ministère de la Santé Publique et de la Population. [ABSTRACT FROM AUTHOR]

Introduction: Dengue fever is the most important mosquito-borne viral disease in the world, with 40% of the global population at risk of infection. Dengue virus is responsible for infections in over 100 countries, including the Americas and Caribbean Basin; however, it has been largely eradicated from the United States through the implementation of effective vector control programs. However, between 2009 and 2010, 27 permanent residents of Key West, Florida, were reported to have locally acquired infections, marking the first autochthonous cases detected in Florida since 1934. Despite this recent and unusual transmission, and the potential risk of serious illness associated with sequential infections, no active surveillance had been conducted since. Materials and Methods: A serosurvey of permanent residents of Key West, Florida, was conducted in March of 2012. After informed consent, enrolled participants ( n=173) were given a dengue virus rapid diagnostic test and completed a corresponding questionnaire. Results: The presence of immunoglobulin G (IgG) antibodies was indicated in 12 participants (6.9%), all of whom reported travel to endemic countries within the past 2 years. Surprisingly, six participants (3.5%) without any recent travel outside the state of Florida gave positive results for IgM antibodies. The presence of birdbaths and bromeliads on the property and sleeping outdoors emerged as significant factors related to previous exposure, whereas home air conditioning without the use of open windows and the use of mosquito repellent were protective. Conclusions: These findings suggest local transmission occurred in Key West in early 2012, indicating that transmission may not have subsided in 2010. [ABSTRACT FROM AUTHOR]

Background: Malaria transmission continues to occur in Haiti, with 25,423 confirmed cases of Plasmodium falciparum and 161,236 suspected infections reported in 2012. At low prevalence levels, passive surveillance measures, which rely primarily on reports from health systems, becomes less appropriate for capturing annual malaria incidence. To improve understanding of malaria transmission in Haiti, participants from the Ouest and Sud-Est departments were screened using a highly sensitive enzyme-linked immunosorbent assay (ELISA). Methods: Between February and May 2013, samples were collected from four different sites including a rural community, two schools, and a clinic located in the Ouest and Sud-Est departments of Haiti. A total of 815 serum samples were screened for malaria antibodies using an indirect ELISA coated with vaccine candidates apical membrane antigen (AMA-1) and merozoite surface protein-1 (MSP-119). The classification of previous exposure was established by using a threshold value that fell three standard deviations above the mean absorbance for suspected seronegative population members (OD of 0.32 and 0.26 for AMA-1 and MSP-1, respectively). The observed seroprevalence values were used to fit a modified reverse catalytic model to yield estimates of seroconversion rates. Results: Of the samples screened, 172 of 815 (21.1%) were AMA-1 positive, 179 of 759 (23.6%) were MSP-119 positive, and 247 of 815 (30.3%) were positive for either AMA-1 or MSP-1; indicating rates of previous infections between 21.1% and 30.3%. Not surprisingly, age was highly associated with the likelihood of previous infection (p-value <0.001). After stratification by age, the estimated seroconversion rate indicated that the annual malaria transmission in the Ouest and Sud-Est department is approximately 2.5% (95% CI SCR: 2.2%, 2.8%). Conclusions: These findings suggest that despite the absence of sustained malaria control efforts in Haiti, transmission has remained relatively low over multiple decades. Elimination in Haiti appears to be feasible; however, surveillance must continue to be strengthened in order to respond to areas with high transmission and measure the impact of future interventions. [ABSTRACT FROM AUTHOR]

Background In Haiti where chloroquine (CQ) is widely used for malaria treatment, reports of resistance are scarce. However, recent identification of CQ resistance genotypes in one site is suggestive of an emerging problem. Additional studies are needed to evaluate genetic mutations associated with CQ resistance, especially in the Plasmodium falciparum multi-drug resistance-1 gene (pfmdr1) while expanding the already available information on P. falciparum CQ transporter gene (pfcrt) in Haiti. Methods Blood samples were collected on Whatman filter cards (FTA) from eight clinics spread across Haiti. Following the confirmation of P. falciparum in the samples, PCR protocols were used to amplify regions of pfmdr1and pfcrt codons of interest, (86, 184, 1034, 1042, and 1246) and (72-76), respectively. Sequencing and site-specific restriction enzyme digestions were used to analyse these DNA fragments for the presence of single nucleotide polymorphisms (SNPs) known to confer resistance to anti-malarial drugs. Results P. falciparum infection was confirmed in 160 samples by amplifying a segment of the P. falciparum 18S small subunit ribosomal RNA gene (pfssurrna). The sequence of pfmdr1 in 54 of these samples was determined between codons 86,184 codons 1034, 1042 and 1246. No sequence differences from that of the NF54 clone 3D7 were found among the 54 samples except at codon 184, where a non-silent mutation was found in all samples predicted to alter the amino acid sequence replacing tyrosine with phenylalanine (Y184F). This altered sequence was also confirmed by restriction enzyme digestion. The sequence of pfmdr1 at codons 86, 184, 1034 and 1042 encoded the NFSN haplotype. The sequence of pfcrt codons 72-76 from 79 samples was determined and found to encode CVMNK, consistent with a CQ sensitive genotype. Conclusion The presence of the Y184F mutation in pfmdr1 of P. falciparum parasites in Haiti may have implications for resistance to antimalarial drugs. The absence of mutation in pfcrt at codon 76 among 79 isolates tested suggests that sensitivity to CQ in Haiti remains common. Widespread screening of the pfmdr1 and pfcrt especially among patients experiencing treatment failure may be a useful tool in early detection of the emergence of antimalarial drug resistance in Haiti. [ABSTRACT FROM AUTHOR]

Background: Malaria is a significant public health concern in Haiti where approximately 30,000 cases are reported annually with CDC estimates as high as 200,000. Malaria infections in Haiti are caused almost exclusively by Plasmodium falciparum, while a small number of Plasmodium malariae and an even smaller number of putative Plasmodium vivax infections have been reported. The lack of confirmed P. vivax infections in Haiti could be due to the genetic background of native Haitians. Having descended from West African populations, many Haitians could be Duffy negative due to a single nucleotide polymorphism from thymine to cytosine in the GATA box of the promoter region of the Duffy antigen receptor for chemokines (DARC) gene. This mutation, encoded by the FYES allele, eliminates the expression of the Duffy antigen on erythrocytes, which reduces invasion by P. vivax. This study investigated the frequency of the FYES allele and P. vivax infections in malaria patients with the goal of uncovering factors for the lack of P. vivax infections reported in Haiti. Methods: DNA was extracted from dried blood spots collected from malaria patients at four clinic locations in Haiti. The samples were analysed by polymerase chain reaction (PCR) for the presence of the P. vivax small subunit ribosomal RNA gene. PCR, sequencing, and restriction enzyme digestion were used to detect the presence of the FYES allele. Matched samples were examined for both presence of P. vivax and the FYES allele. Results: No cases of P. vivax were detected in any of the samples (0/136). Of all samples tested for the FYES allele, 99.4% had the FYES allele (163/164). Of the matched samples, 99% had the FYES allele (98/99). Conclusions: In this preliminary study, no cases of P. vivax were confirmed by PCR and 99% of the malaria patients tested carried the FYES allele. The high frequency of the FYES allele that silences erythroid expression of the Duffy antigen offers a biologically plausible explanation for the lack of P. vivax infections observed. These results provide insights on the host susceptibility for P. vivax infections that has never before been investigated in Haiti. [ABSTRACT FROM AUTHOR]

Background: Malaria caused by Plasmodium falciparum infects roughly 30,000 individuals in Haiti each year. Haiti has used chloroquine (CQ) as a first-line treatment for malaria for many years and as a result there are concerns that malaria parasites may develop resistance to CQ over time. Therefore it is important to prepare for alternative malaria treatment options should CQ resistance develop. In many other malaria-endemic regions, antifolates, particularly pyrimethamine (PYR) and sulphadoxine (SDX) treatment combination (SP), have been used as an alternative when CQ resistance has developed. This study evaluated mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes that confer PYR and SDX resistance, respectively, in P. falciparum to provide baseline data in Haiti. This study is the first comprehensive study to examine PYR and SDX resistance genotypes in P. falciparum in Haiti. Methods: DNA was extracted from dried blood spots and genotyped for PYR and SDX resistance mutations in P. falciparum using PCR and DNA sequencing methods. Sixty-one samples were genotyped for PYR resistance in codons 51, 59, 108 and 164 of the dhfr gene and 58 samples were genotyped for SDX resistance codons 436, 437, 540 of the dhps gene in P. falciparum. Results: Thirty-three percent (20/61) of the samples carried a mutation at codon 108 (S108N) of the dhfr gene. No mutations in dhfr at codons 51, 59, 164 were observed in any of the samples. In addition, no mutations were observed in dhps at the three codons (436, 437, 540) examined. No significant difference was observed between samples collected in urban vs rural sites (Welch's T-test p-value = 0.53 and permutations p-value = 0.59). Conclusion: This study has shown the presence of the S108N mutation in P. falciparum that confers low-level PYR resistance in Haiti. However, the absence of SDX resistance mutations suggests that SP resistance may not be present in Haiti. These results have important implications for ongoing discussions on alternative malaria treatment options in Haiti. [ABSTRACT FROM AUTHOR]

Mayaro virus has been associated with small outbreaks in northern South America. We isolated this virus from a child with acute febrile illness in rural Haiti, confirming its role as a cause of mosquitoborne illness in the Caribbean region. The clinical presentation can mimic that of chikungunya, dengue, and Zika virus infections. [ABSTRACT FROM AUTHOR]

Glycolysis, the citric acid cycle and other metabolic pathways of living organisms generate potentially toxic acids within all cells. One ubiquitous mechanism for ridding cells of the acids is to expel H+ in exchange for extracellular Na+, mediated by electroneutral transporters called Na+/H+ exchangers (NHEs) that are driven by Na+ concentration gradients. The exchange must be important because the human genome contains 10 NHEs along with two Na+/H+ antiporters (NHAs). By contrast, the genomes of two principal disease vector mosquitoes, Anopheles gambiae and Aedes aegypti, contain only three NHEs along with the two NHAs. This shortfall may be explained by the presence of seven nutrient amino acid transporters (NATs) in the mosquito genomes. NATs transport Na+ stoichiometrically linked to an amino acid into the cells by a process called symport or co-transport. Three of the mosquito NATs and two caterpillar NATs have previously been investigated after heterologous expression in Xenopus laevis oocytes and were found to be voltage driven (electrophoretic). Moreover, the NATs are present in the same membrane as the H+ V-ATPase, which generates membrane potentials as high as 120mV. We review evidence that the H+ V-ATPase moves H+ out of the cells and the resulting membrane potential (Vm) drives Na+ linked to an amino acid into the cells via a NAT. The H+ efflux by the V-ATPase and Na+ influx by the NAT comprise the same ion exchange as that mediated by an NHE; so the V and NAT working together constitute an NHE that we call NHEVNAT. As the H+ V-ATPase is widely distributed in mosquito epithelial cells and there are seven NATs in the mosquito genomes, there are potentially seven NHEVNATs that could replace the missing NHEs. We review published evidence in support of this hypothesis and speculate about broader functions of NHEVNATs. [ABSTRACT FROM AUTHOR]

Background: During an entomological survey in preparation for malaria control interventions in Mwea division, the number of malaria cases at the Kimbimbi sub-district hospital was in a steady decline. The underlying factors for this reduction were unknown and needed to be identified before any malaria intervention tools were deployed in the area. We therefore set out to investigate the potential factors that could have contributed to the decline of malaria cases in the hospital by analyzing the malaria control knowledge, attitudes and practices (KAP) that the residents in Mwea applied in an integrated fashion, also known as integrated malaria management (IMM). Methods: Integrated Malaria Management was assessed among community members of Mwea division, central Kenya using KAP survey. The KAP study evaluated community members' malaria disease management practices at the home and hospitals, personal protection measures used at the household level and malaria transmission prevention methods relating to vector control. Concurrently, we also passively examined the prevalence of malaria parasite infection via outpatient admission records at the major referral hospital in the area. In addition we studied the mosquito vector population dynamics, the malaria sporozoite infection status and entomological inoculation rates (EIR) over an 8 month period in 6 villages to determine the risk of malaria transmission in the entire division. Results: A total of 389 households in Mwea division were interviewed in the KAP study while 90 houses were surveyed in the entomological study. Ninety eight percent of the households knew about malaria disease while approximately 70% of households knew its symptoms and methods to manage it. Ninety seven percent of the interviewed households went to a health center for malaria diagnosis and treatment. Similarly a higher proportion (81%) used anti-malarial medicines bought from local pharmacies. Almost 90% of households reported owning and using an insecticide treated bed net and 81% reported buying the nets within the last 5 years. The community also used mosquito reduction measures including, in order of preference, environmental management (35%), mosquito repellent and smoke (31%) insecticide canister sprays (11%), and window and door screens (6%). These methods used by the community comprise an integrated malaria management (IMM) package. Over the last 4 years prior to this study, the malaria cases in the community hospital reduced from about 40% in 2000 to less than 10% by 2004 and by the year 2007 malaria cases decreased to zero. In addition, a one time crosssectional malaria parasite survey detected no Plasmodium infection in 300 primary school children in the area. Mosquito vector populations were variable in the six villages but were generally lower in villages that did not engage in irrigation activities. The malaria risk as estimated by EIR remained low and varied by village and proximity to irrigation areas. The average EIR in the area was estimated at 0.011 infectious bites per person per day. Conclusions: The usage of a combination of malaria control tools in an integrated fashion by residents of Mwea division might have influenced the decreased malaria cases in the district hospital and in the school children. A vigorous campaign emphasizing IMM should be adopted and expanded in Mwea division and in other areas with different eco-epidemiological patterns of malaria transmission. With sustained implementation and support from community members integrated malaria management can reduce malaria significantly in affected communities in Africa. [ABSTRACT FROM AUTHOR]

Mosquito larvae live in dynamic aqueous environments, which can fluctuate drastically in salinity due to environmental events such as rainfall and evaporation. Larval survival depends upon the ability to regulate hemolymph osmolarity by absorbing and excreting ions. A major organ involved in ion regulation is the rectum, the last region for modification of the primary urine before excretion. The ultrastructure and function of culicine larval recta have been studied extensively; however, very little published data exist on the recta of anopheline larvae. To gain insight into the structure and functions of this organ in anopheline species, we used immunohistochemistry to compare the localization of three proteins [carbonic anhydrase (CA9), Na+/K+ P-ATPase and H+ V-ATPase] in the recta of anopheline larvae reared in freshwater and saline water with the localization of the same proteins in culicine larvae reared under similar conditions. Based on the following key points, we concluded that anophelines differ from culicines in larval rectal structure and in regulation of protein expression: (1) despite the fact that obligate freshwater and saline- tolerant culicines have structurally distinct recta, all anophelines examined (regardless of saline-tolerance) have a structurally similar rectum consisting of distinct DAR (dorsal anterior rectal) cells and non-DAR cells; (2) anopheline larvae undergo a dramatic shift in rectal Na+/K+-ATPase localization when reared in freshwater vs saline water. This shift is not seen in any culicine larvae examined. Additionally, we use these immunohistochemical analyses to suggest possible functions for the DAR and non- DAR cells of anopheline larvae in freshwater and saline conditions. [ABSTRACT FROM AUTHOR]

The nutrient amino acid transporter (NAT) subfamily is the largest subdivision of the sodium neurotransmitter symporter family (SNF; also known as SLC6; HUGO). There are seven members of the NAT population in the African malaria mosquito Anopheles gambiae, two of which, AgNAT6 and AgNAT8, preferably transport indole- and phenyl-branched substrates, respectively. The relative expression and distribution of these aromatic NATs were examined with transporter-specific antibodies in Xenopus oocytes and mosquito larval alimentary canal, representing heterologous and tissue expression systems, respectively. NAT- specific aromatic-substrate-induced currents strongly corresponded with specific accumulation of both transporters in the plasma membrane of oocytes. Immunolabeling revealed elevated expressions of both transporters in specific regions of the larval alimentary canal, including salivary glands, cardia, gastric caeca, posterior midgut and Malpighian tubules. Differences in relative expression densities and spatial distribution of the transporters were prominent in virtually all of these regions, suggesting unique profiles of the aromatic amino acid absorption. For the first time reversal of the location of a transporter between apical and basal membranes was identified in posterior and anterior epithelial domains corresponding with secretory and absorptive epithelial functions, respectively. Both aromatic NATs formed putative homodimers in the larval gut whereas functional monomers were over-expressed heterologously in Xenopus oocytes. The results unequivocally suggest functional synergy between substrate-specific AgNAT6 and AgNAT8 in intracellular absorption of aromatic amino acids. More broadly, they suggest that the specific selectivity, regional expression and polarized membrane docking of NATs represent key adaptive traits shaping functional patterns of essential amino acid absorption in the metazoan alimentary canal and other tissues. [ABSTRACT FROM AUTHOR]

Anopheles gambiae larvae (Diptera: Culicidae) live in freshwater with low Na+ concentrations yet they use Na+ for alkalinization of the alimentary canal, for electrophoretic amino acid uptake and for nerve function. The metabolic pathway by which larvae accomplish these functions has anionic and cationic components that interact and allow the larva to conserve Na+ while excreting H+ and HCO3-. The anionic pathway consists of a metabolic CO2 diffusion process, carbonic anhydrase and CI-/HCO3- exchangers; it provides weak HCO3- and weaker CO32- anions to the lumen. The cationic pathway consists of H+ V-ATPases and Na+/H+ antiporters (NHAs), Na+/K+ P-ATPases and Na+/H+ exchangers (NHEs) along with several (Na+ or K+):amino acid+/- symporters, a.k.a. nutrient amino acid transporters (NATs). This paper considers the cationic pathway, which provides the strong Na+ or K+ cations that alkalinize the lumen in anterior midgut then removes them and restores a lower pH in posterior midgut. A key member of the cationic pathway is a Na+/H+ antiporter, which was cloned recently from Anopheles gambiae larvae, localized strategically in plasma membranes of the alimentary canal and named AgNHA1 based upon its phylogeny. A phylogenetic comparison of all cloned NHAs and NHEs revealed that AgNHA1 is the first metazoan NHA to be cloned and localized and that it is in the same clade as electrophoretic prokaryotic NHAs that are driven by the electrogenic H+ F-ATPase. Like prokaryotic NHAs, AgNHA1 is thought to be electrophoretic and to be driven by the electrogenic H+ V-ATPase. Both AgNHA1 and alkalophilic bacterial NHAs face highly alkaline environments; to alkalinize the larva mosquito midgut lumen, AgNHA1, like the bacterial NHAs, would have to move nH+ inwardly and Na+ outwardly. Perhaps the alkaline environment that led to the evolution of electrophoretic prokaryotic NHAs also led to the evolution of an electrophoretic AgNHA1 in mosquito larvae. In support of this hypothesis, antibodies to both AgNHA1 and H+ V-ATPase label the same membranes in An. gambiae larvae. The localization of H+ V-ATPase together with (Na+ or K+):amino acid+/- symporter, AgNAT8, on the same apical membrane in posterior midgut cells constitutes the functional equivalent of an NHE that lowers the pH in the posterior midgut lumen. All NATs characterized to date are Na+ or K+ symporters so the deduction is likely to have wide application. The deduced colocalization of H+ V-ATPase, AgNHA1 and AgNAT8, on this membrane forms a pathway for local cycling of H+ and Na+ in posterior midgut. The local H+ cycle would prevent unchecked acidification of the lumen while the local Na+ cycle would regulate pH and support Na+:amino acid+/- symport. Meanwhile, a long-range Na+ cycle first transfers Na+ from the blood to gastric caeca and anterior midgut lumen where it initiates alkalinization and then returns Na+ from the rectal lumen to the blood, where it prevents loss of Na+ during H+ and HCO3 excretion. The localization of H+ V-ATPase and Na+/K+-ATPase in An. gambiae larvae parallels that reported for Aedes aegypti larvae. The deduced colocalization of the two ATPases along with NHA and NAT in the alimentary canal constitutes a cationic pathway for Na+-conserving midgut alkalinization and de-alkalinization which has never been reported before. [ABSTRACT FROM AUTHOR]

We have cloned a cDNA encoding a new ion transporter from the alimentary canal of larval African malaria mosquito, Anopheles gambiae Giles sensu stricto. Phylogenetic analysis revealed that the corresponding gene is in a group that has been designated NHA, and which includes (Na+ or K+)/H+ antiporters; so the novel transporter is called AgNHA1. The annotation of current insect genomes shows that both AgNHA1 and a close relative, AgNHA2, belong to the cation proton antiporter 2 (CPA2) subfamily and cluster in an exclusive clade of genes with high identity from Aedes aegypti, Drosophila melanogaster, D. pseudoobscura, Apis mellifera and Tribolium castaneum. Although NHA genes have been identified in all phyla for which genomes are available, no NHA other than AgNHA1 has previously been cloned, nor have the encoded proteins been localized or characterized. The AgNHA1 transcript was localized in An. gambiae larvae by quantitative real-time PCR (qPCR) and in situ hybridization. AgNHA1 message was detected in gastric caeca and rectum, with much weaker transcription in other parts of the alimentary canal. Immunolabeling of whole mounts and longitudinal sections of isolated alimentary canal showed that AgNHA1 is expressed in the cardia, gastric caeca, anterior midgut, posterior midgut, proximal Malpighian tubules and rectum, as well as in the subesophageal and abdominal ganglia. A phylogenetic analysis of NHAs and KHAs indicates that they are ubiquitous. A comparative molecular analysis of these antiporters suggests that they catalyze electrophoretic alkali metal ion/hydrogen ion exchanges that are driven by the voltage from electrogenic H+ V-ATPases. The tissue localization of AgNHA1 suggests that it plays a key role in maintaining the characteristic longitudinal pH gradient in the lumen of the alimentary canal of An. gambiae larvae. [ABSTRACT FROM AUTHOR]

Background: The origin of highly competent malaria vectors has been linked to productive larval habitats in the field, but there isn't solid quantitative or qualitative data to support it. To test this, the effect of larval habitat soil substrates on larval development time, pupation rates and vector competence of Anopheles gambiae to Plasmodium falciparum were examined. Methods: Soils were collected from active larval habitats with sandy and clay substrates from field sites and their total organic matter estimated. An. gambiae larvae were reared on these soil substrates and the larval development time and pupation rates monitored. The emerging adult mosquitoes were then artificially fed blood with infectious P. falciparum gametocytes from human volunteers and their midguts examined for oocyst infection after seven days. The wing sizes of the mosquitoes were also measured. The effect of autoclaving the soil substrates was also evaluated. Results: The total organic matter was significantly different between clay and sandy soils after autoclaving (P = 0.022). A generalized liner model (GLM) analysis identified habitat type (clay soil, sandy soil, or lake water) and autoclaving (that reduces presence of microbes) as significant factors affecting larval development time and oocyst infection intensities in adults. Autoclaving the soils resulted in the production of significantly smaller sized mosquitoes (P = 0.008). Autoclaving clay soils resulted in a significant reduction in Plasmodium falciparum oocyst intensities (P = 0.041) in clay soils (unautoclaved clay soils (4.28 ± 0.18 oocysts/midgut; autoclaved clay soils = 1.17 ± 0.55 oocysts/midgut) although no difference (P = 0.480) in infection rates was observed between clay soils (10.4%), sandy soils (5.3%) or lake water (7.9%). Conclusion: This study suggests an important nutritional role for organic matter and microbial fauna on mosquito fitness and vector competence. It shows that the quality of natural aquatic habitats of mosquito larvae may influence malaria parasite transmission potential by An. gambiae. This information can be important in targeting larval habitats for malaria control. [ABSTRACT FROM AUTHOR]

Provides information on the study on the effects of high temperature on early Plasmodium falciparum development in Anopheles gambiae experimentally infected with gametocytes with mean density. Dissection of several batches of mosquitoes in their midguts at 24 hour for ookinete enumeration to quantify oocysts; Intensity of the average oocyst for infected mosquitoes; Result of the exposure of mosquitoes infected with natural parasites to high temperatures on preoocyst stages.

Background: Studies on Plasmodium falciparum gametocyte development and dynamics have almost exclusively focused on patients treated with antimalarial drugs, while the majority of parasite carriers in endemic areas are asymptomatic. This study identified factors that influence gametocytaemia in asymptomatic children in the absence and presence of pyrimethaminesulphadoxine (SP) antimalarial treatment. Methods: A cohort of 526 children (6 months - 16 years) from western Kenya was screened for asexual parasites and gametocytes and followed weekly up to four weeks. Children with an estimated parasitaemia of =1,000 parasites/μl were treated with SP according to national guidelines. Factors associated with gametocyte development and persistence were determined in untreated and SP-treated children with P. falciparum mono-infection. Results: Gametocyte prevalence at enrolment was 33.8% in children below five years of age and decreased with age. In the absence of treatment 18.6% of the children developed gametocytaemia during follow-up; in SP-treated children this proportion was 29.8%. Age, high asexual parasite density and gametocyte presence at enrolment were predictive factors for gametocytaemia. The estimated mean duration of gametocytaemia for children below five, children from five to nine and children ten years and above was 9.4, 7.8 and 4.1 days, respectively. Conclusion: This study shows that a large proportion of asymptomatic untreated children develop gametocytaemia. Gametocytaemia was particularly common in children below five years who harbor gametocytes for a longer period of time. The age-dependent duration of gametocytaemia has not been previously shown and could increase the importance of this agegroup for the infectious reservoir. [ABSTRACT FROM AUTHOR]