RESUMO
Aedes mosquitoes are important vectors of re-emerging diseases in developing countries, and increasing exposure to Aedes in the developed world is currently a source of concern. Given the limitations of current entomologic methods, there is a need for a new effective way for evaluating Aedes exposure. Our objective was to evaluate specific antibody responses to Aedes aegypti saliva as a biomarker for vector exposure in a dengue-endemic urban area. IgG responses to saliva were strong in young children and steadily waned with age. Specific IgG levels were significantly higher in persons living in sites with higher Ae. aegypti density, as measured by using entomologic parameters. Logistic regression showed a significant correlation between IgG to saliva and exposure level, independently of either age or sex. These results suggest that antibody responses to saliva could be used to monitor human exposure to Aedes bites.
Assuntos
Formação de Anticorpos/imunologia , Biomarcadores/sangue , Mordeduras e Picadas/diagnóstico , Dengue/epidemiologia , Dengue/transmissão , Adolescente , Adulto , Aedes , Animais , Bolívia/epidemiologia , Análise por Conglomerados , Países em Desenvolvimento , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Insetos Vetores/imunologia , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Saliva/imunologia , População Urbana , Adulto JovemRESUMO
The origin of Plasmodium falciparum in South America is controversial. Some studies suggest a recent introduction during the European colonizations and the transatlantic slave trade. Other evidence--archeological and genetic--suggests a much older origin. We collected and analyzed P. falciparum isolates from different regions of the world, encompassing the distribution range of the parasite, including populations from sub-Saharan Africa, the Middle East, Southeast Asia, and South America. Analyses of microsatellite and SNP polymorphisms show that the populations of P. falciparum in South America are subdivided in two main genetic clusters (northern and southern). Phylogenetic analyses, as well as Approximate Bayesian Computation methods suggest independent introductions of the two clusters from African sources. Our estimates of divergence time between the South American populations and their likely sources favor a likely introduction from Africa during the transatlantic slave trade.
Assuntos
Demografia , Emigração e Imigração , Variação Genética , Filogenia , Plasmodium falciparum/genética , Teorema de Bayes , Análise por Conglomerados , Genética Populacional , Humanos , Modelos Logísticos , Repetições de Microssatélites/genética , Modelos Genéticos , Filogeografia , Plasmodium falciparum/classificação , Polimorfismo de Nucleotídeo Único/genética , Análise de Componente Principal , América do SulRESUMO
Plasmodium vivax isolates from French Guiana were studied for the presence of mutations associated with sulfadoxine/pyrimethamine (SP) drug resistance. Ninety-six blood samples were collected from 2000 to 2005 from symptomatic malaria patients. SP drug resistance was predicted by determining point mutations in the dihydrofolate reductase (pvdhfr) and dihydropteroate synthase (pvdhps) genes. All samples showed mutant genotypes in both genes with a prevalence > 90% for the 58R, 117N, 382C, and 383G. A new mutation (116G) in pvdhfr was found at a frequency of 3.3%. Six different pvdhfr/dhps multilocus genotypes were observed with the predominance of the quintuple mutant-type 58R/117N/173L-382C/383G (59.3%). No significant differences were observed between the prevalence of haplotypes and the year of collection. Our results indicate that, in this area, the fixation of SP drug-resistant parasites in the P. vivax population is stable.
Assuntos
Antimaláricos/farmacologia , Di-Hidropteroato Sintase/genética , Mutação , Plasmodium vivax/efeitos dos fármacos , Plasmodium vivax/genética , Pirimetamina/farmacologia , Sulfadoxina/farmacologia , Tetra-Hidrofolato Desidrogenase/genética , Animais , Combinação de Medicamentos , Resistência a Medicamentos , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: The antimalarial drug atovaquone specifically targets Plasmodium falciparum cytochrome b (Pfcytb), a mitochondrial gene with uniparental inheritance. Cases of resistance to atovaquone associated with mutant Pfcytb have been reported, justifying efforts to better document the natural polymorphism of this gene. To this end, a large molecular survey was conducted in several malaria endemic areas where atovaquone was not yet in regular use. METHODS: The polymorphism of the Pfcytb was analysed by direct sequencing of PCR products corresponding to the full length coding region. Sequence was generated for 671 isolates originating from three continents: Africa (Senegal, Ivory Coast, Central African Republic and Madagascar), Asia (Cambodia) and South America (French Guiana). RESULTS: Overall, 11 polymorphic sites were observed, of which eight were novel mutations. There was a large disparity in the geographic distribution of the mutants. All isolates from Senegal, Central African Republic and Madagascar displayed a Camp/3D7 wild type Pfcytb sequence, as did most samples originating from Cambodia and Ivory Coast. One synonymous (t759a at codon V253V) and two non-synonymous (t553g and a581g at codons F185V and H194R, respectively) singletons were detected in Ivory Coast. Likewise, two synonymous (a126t and c793t at codons -T42T and L265L, respectively) singletons were observed in Cambodia. In contrast, seven mutated sites, affecting seven codons and defining four mutant haplotypes were observed in French Guiana. The wild type allele was observed in only 14% of the French Guiana isolates. The synonymous c688t mutation at position L230L was highly prevalent; the most frequent allele was the c688t single mutant, observed in 84% of the isolates. The other alleles were singletons (a126t/a165c, a4g/a20t/a1024c and a20t/t341c/c688t corresponding to T42T/S55S, N2D/N71I/I342L, N71I/L114S/L230L, respectively" please replace with ' corresponding to T42T/S55S, N2D/N71I/I342L and N71I/L114S/L230L, respectively). The codon 268 polymorphisms associated with atovaquone resistance were not observed in the panel the isolates studied. Overall, the wild type PfCYTb protein isoform was highly predominant in all study areas, including French Guiana, suggesting stringent functional constraints. CONCLUSION: These data along with previously identified Pfcytb field polymorphisms indicate a clustering of molecular signatures, suggesting different ancestral types in South America and other continents. The absence of mutations associated with most atovaquone-proguanil clinical failures indicates that the atovaquone-proguanil association is an interesting treatment option in the study areas.
Assuntos
Citocromos b/genética , Malária Falciparum/patologia , Plasmodium falciparum/genética , Polimorfismo Genético , África , Substituição de Aminoácidos/genética , Animais , Ásia , DNA Mitocondrial/genética , DNA de Protozoário/genética , Resistência a Medicamentos/genética , Humanos , Plasmodium falciparum/isolamento & purificação , Análise de Sequência , América do SulAssuntos
Antimaláricos , Atovaquona , Resistência a Medicamentos , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Proguanil/uso terapêutico , Animais , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Atovaquona/farmacologia , Atovaquona/uso terapêutico , Quimioterapia Combinada , Humanos , Malária Falciparum/parasitologia , Testes de Sensibilidade Parasitária , Proguanil/farmacologia , América do SulRESUMO
O objetivo deste estudo foi o de explorar (em Curaçá, município do Estado da Bahia, no Nordeste brasileiro) os possíveis fatores associados à infestação das moradias pelo Triatoma brasiliensis ou Triatoma pseudomaculata, dois triatomas das espécies silvestres. Usamos uma análise "logística" de múltipla regressão para mostrar como as características estruturais da área do peridomicílio associadas ao número de animais e a fatores sociológicos favorecem a infestação em algumas moradias. Isso sugere que T. brasilienses está associado às atividades humanas enquanto T. pseudomaculata está associado à vegetação e aos animais. Assim, o manejo da pecuária é um importante fator de risco para a infestação de triatomíneos.
Assuntos
Humanos , Animais , Triatominae , Controle de Vetores de Doenças , Fatores de RiscoRESUMO
The aim of this study in Curaça, Bahia, Northeast Brazil was to explore possible factors associated with the infestation of human dwellings by Triatoma brasiliensis or Triatoma pseudomaculata, two sylvatic triatomine species. We use multiple logistic regression analysis to show how structural features of the peridomiciliary area combine with the number of animals and sociological factors to allow infestation of some dwellings. It is suggested that T. brasiliensis is associated with human activities, while T. pseudomaculata is associated with vegetation and animals. Peridomiciliary farm animals are a strong risk factor for triatomine infestation.