Duffy blood group gene polymorphisms among malaria vivax patients in four areas of the Brazilian Amazon region

<p>Abstract</p> <p>Background</p> <p>Duffy blood group polymorphisms are important in areas where <it>Plasmodium vivax </it>predominates, because this molecule acts as a receptor for this protozoan. In the present study, Duffy blood group genotyping in <it>P. vivax </it>malaria patients from four different Brazilian endemic areas is reported, exploring significant associations between blood group variants and susceptibility or resistance to malaria.</p> <p>Methods</p> <p>The <it>P. vivax </it>identification was determined by non-genotypic and genotypic screening tests. The Duffy blood group was genotyped by PCR/RFLP in 330 blood donors and 312 malaria patients from four Brazilian Amazon areas. In order to assess the variables significance and to obtain independence among the proportions, the Fisher's exact test was used.</p> <p>Results</p> <p>The data show a high frequency of the <it>FYA/FYB </it>genotype, followed by <it>FYB/FYB, FYA/FYA</it>, <it>FYA/FYB-33 </it>and <it>FYB/FYB-33</it>. Low frequencies were detected for the <it>FYA/FY</it>^<it>X</it>, <it>FYB/FY</it>^<it>X</it>, <it>FYX/FY</it>^{<it>X </it>}and <it>FYB-33/FYB-33 </it>genotypes. Negative Duffy genotype (<it>FYB-33/FYB-33</it>) was found in both groups: individuals infected and non-infected (blood donors). No individual carried the <it>FY</it>^<it>X</it><it>/FYB-33 </it>genotype. Some of the Duffy genotypes frequencies showed significant differences between donors and malaria patients.</p> <p>Conclusion</p> <p>The obtained data suggest that individuals with the <it>FYA/FYB </it>genotype have higher susceptibility to malaria. The presence of the <it>FYB-33 </it>allele may be a selective advantage in the population, reducing the rate of infection by <it>P. vivax </it>in this region. Additional efforts may contribute to better elucidate the physiopathologic differences in this parasite/host relationship in regions endemic for <it>P. vivax </it>malaria, in particular the Brazilian Amazon region.</p

Epidemiology of Disappearing Plasmodium vivax Malaria: A Case Study in Rural Amazonia

Background: New frontier settlements across the Amazon Basin pose a major challenge for malaria elimination in Brazil. Here we describe the epidemiology of malaria during the early phases of occupation of farming settlements in Remansinho area, Brazilian Amazonia. We examine the relative contribution of low-density and asymptomatic parasitemias to the overall Plasmodium vivax burden over a period of declining transmission and discuss potential hurdles for malaria elimination in Remansinho and similar settings. Methods: Eight community-wide cross-sectional surveys, involving 584 subjects, were carried out in Remansinho over 3 years and complemented by active and passive surveillance of febrile illnesses between the surveys. We used quantitative PCR to detect low-density asexual parasitemias and gametocytemias missed by conventional microscopy. Mixed-effects multiple logistic regression models were used to characterize independent risk factors for P. vivax infection and disease. Principal Findings/Conclusions P. vivax prevalence decreased from 23.8% (March–April 2010) to 3.0% (April–May 2013), with no P. falciparum infections diagnosed after March–April 2011. Although migrants from malaria-free areas were at increased risk of malaria, their odds of having P. vivax infection and disease decreased by 2–3% with each year of residence in Amazonia. Several findings indicate that low-density and asymptomatic P. vivax parasitemias may complicate residual malaria elimination in Remansinho: (a) the proportion of subpatent infections (i.e. missed by microscopy) increased from 43.8% to 73.1% as P. vivax transmission declined; (b) most (56.6%) P. vivax infections were asymptomatic and 32.8% of them were both subpatent and asymptomatic; (c) asymptomatic parasite carriers accounted for 54.4% of the total P. vivax biomass in the host population; (d) over 90% subpatent and asymptomatic P. vivax had PCR-detectable gametocytemias; and (e) few (17.0%) asymptomatic and subpatent P. vivax infections that were left untreated progressed to clinical disease over 6 weeks of follow-up and became detectable by routine malaria surveillance

Duffy Negative Antigen Is No Longer a Barrier to Plasmodium vivax – Molecular Evidences from the African West Coast (Angola and Equatorial Guinea)

Recent reports of Plasmodium vivax infections, the most widely distributed species of human malaria, show that this parasite is evolving and adapting, becoming not only more aggressive but also more frequent in countries where it was not present in the past, becoming, therefore, a major source of concern. Thus, it is extremely important to perform new studies of its distribution in West and Central Africa, where there are few reports of its presence, due to the high prevalence of Duffy-negative individuals. The aim of this study was to investigate the presence of P. vivax in Angola and in Equatorial Guinea, using blood samples and mosquitoes. The results showed that P. vivax seems to be able to invade erythrocytes using receptors other than Duffy, and this new capacity is not exclusive to one strain of P. vivax, since we have found samples infected with two different strains: VK247 and classic. Additionally we demonstrated that the parasite has a greater distribution than previously thought, calling for a reevaluation of its worldwide distribution

The International Limits and Population at Risk of Plasmodium vivax Transmission in 2009

Growing evidence shows that Plasmodium vivax malaria is clinically less benign than has been commonly believed. In addition, it is the most widely distributed species of human malaria and is likely to cause more illness in certain regions than the more extensively studied P. falciparum malaria. Understanding where P. vivax transmission exists and measuring the number of people who live at risk of infection is a fundamental first step to estimating the global disease toll. The aim of this paper is to generate a reliable map of the worldwide distribution of this parasite and to provide an estimate of how many people are exposed to probable infection. A geographical information system was used to map data on the presence of P. vivax infection and spatial information on climatic conditions that impede transmission (low ambient temperature and extremely arid environments) in order to delineate areas where transmission was unlikely to take place. This map was combined with population distribution data to estimate how many people live in these areas and are, therefore, exposed to risk of infection by P. vivax malaria. The results show that 2.85 billion people were exposed to some level of risk of transmission in 2009

Leishmaniose tegumentar americana no Estado do Acre, Brasil

OBJETIVO: Apresentar levantamento estatístico descritivo da leishmaniose tegumentar americana (LTA) no Estado do Acre. MÉTODOS: Os dados obtidos foram extraídos dos formulários da "Campanha Contra a Leishmaniose", no período de janeiro de 1992 a dezembro de 1997. As variáveis estudadas foram submetidas a análise estatística descritiva. RESULTADOS: O total de casos registrados foi de 2.557. Foi adotada a divisão do Acre em meso e microrregiões para apresentação dos resultados. A maior prevalência foi na microrregião de Brasiléia (231,8 casos/10.000 hab.). A forma clínica predominante foi cutânea (84,05%). A maior ocorrência foi no sexo masculino (71,02%). Portadores com idade de até 24 anos corresponderam a 50% dos casos. Há uma predominância nas ocupações rurais. O exame clínico foi usado para diagnosticar 83,97% dos casos. A maior média de tempo de espera para procurar tratamento médico foi registrada na mesorregião do Vale do Juruá (10,37 meses). CONCLUSÃO: Os altos índices de LTA cutâneo e cutâneo-mucosa encontrados sugerem a necessidade de serem feitas pesquisas sobre os reflexos psicossociais e para identificar fatores que influem na demora do tratamento dos casos

Leishmaniose tegumentar americana no Estado do Acre, Brasil

OBJETIVO: Apresentar levantamento estatístico descritivo da leishmaniose tegumentar americana (LTA) no Estado do Acre. MÉTODOS: Os dados obtidos foram extraídos dos formulários da "Campanha Contra a Leishmaniose", no período de janeiro de 1992 a dezembro de 1997. As variáveis estudadas foram submetidas a análise estatística descritiva. RESULTADOS: O total de casos registrados foi de 2.557. Foi adotada a divisão do Acre em meso e microrregiões para apresentação dos resultados. A maior prevalência foi na microrregião de Brasiléia (231,8 casos/10.000 hab.). A forma clínica predominante foi cutânea (84,05%). A maior ocorrência foi no sexo masculino (71,02%). Portadores com idade de até 24 anos corresponderam a 50% dos casos. Há uma predominância nas ocupações rurais. O exame clínico foi usado para diagnosticar 83,97% dos casos. A maior média de tempo de espera para procurar tratamento médico foi registrada na mesorregião do Vale do Juruá (10,37 meses). CONCLUSÃO: Os altos índices de LTA cutâneo e cutâneo-mucosa encontrados sugerem a necessidade de serem feitas pesquisas sobre os reflexos psicossociais e para identificar fatores que influem na demora do tratamento dos casos