RÉSUMÉ
This study analyzed the evolution of socioeconomic, sanitary, and personal factors as well as spatiotemporal changes in the prevalence of helminthiasis and giardiasis in urban Amazonian children between 2003 and 2011. Child age, lack of sanitation, and lack of access to bottled water were identified as significant associated factors for helminthiasis and giardiasis. There was an overall improvement in socioeconomic and sanitary conditions in the city resulting in decreased helminth prevalences from 12.42 to 9.63% between 2003 and 2010, but the prevalence increased to 15.03% in 2011 due to migratory movement and unstable sanitary conditions. As for Giardiasis, socioeconomic and environmental changes were not enough to reduce prevalence (16% in 2003 and 23% in 2011). Spatial analysis identified a significant cluster for helminthiasis in an area of poor housing conditions. Control programs in the Amazon need to target high-risk areas focusing changes in sanitation, water usage, and health education.
Sujet(s)
Giardiase/épidémiologie , Helminthiase/épidémiologie , Facteurs socioéconomiques , Enfant , Enfant d'âge préscolaire , Villes , Femelle , Giardiase/économie , Helminthiase/économie , Humains , Mâle , Prévalence , Facteurs de risque , Amélioration du niveau sanitaireRÉSUMÉ
Vaccinia virus strains from the family Poxviridae have been frequently isolated in Brazil and associated with outbreaks of exanthematic disease affecting cows and humans. An ELISA IgG was applied to evaluate the seroprevalence of orthopoxviruses in a community located in a rural settlement in the Amazon region, where no orthopoxvirus outbreaks have yet been reported. An overall seroprevalence of 27.89% was found, and it was 23.38% in the non-vaccinated population (smallpox vaccination). These results strongly suggest that orthopoxviruses circulate in this population, and it is the first finding of seropositivity for orthopoxviruses in a population without any previously reported outbreaks.
Sujet(s)
Immunoglobuline G/sang , Orthopoxvirus/immunologie , Infections à Poxviridae/épidémiologie , Adolescent , Adulte , Sujet âgé , Anticorps antiviraux/sang , Brésil/épidémiologie , Enfant , Enfant d'âge préscolaire , Études transversales , Test ELISA , Femelle , Humains , Nourrisson , Mâle , Adulte d'âge moyen , Odds ratio , Infections à Poxviridae/immunologie , Infections à Poxviridae/virologie , Facteurs de risque , Population rurale , Études séroépidémiologiques , Jeune adulteRÉSUMÉ
We describe the epidemiology of malaria in a frontier agricultural settlement in Brazilian Amazonia. We analysed the incidence of slide-confirmed symptomatic infections diagnosed between 2001 and 2006 in a cohort of 531 individuals (2281.53 person-years of follow-up) and parasite prevalence data derived from four cross-sectional surveys. Overall, the incidence rates of Plasmodium vivax and P. falciparum were 20.6/100 and 6.8/100 person-years at risk, respectively, with a marked decline in the incidence of both species (81.4 and 56.8%, respectively) observed between 2001 and 2006. PCR revealed 5.4-fold more infections than conventional microscopy in population-wide cross-sectional surveys carried out between 2004 and 2006 (average prevalence, 11.3 vs. 2.0%). Only 27.2% of PCR-positive (but 73.3% of slide-positive) individuals had symptoms when enrolled, indicating that asymptomatic carriage of low-grade parasitaemias is a common phenomenon in frontier settlements. A circular cluster comprising 22.3% of the households, all situated in the area of most recent occupation, comprised 69.1% of all malaria infections diagnosed during the follow-up, with malaria incidence decreasing exponentially with distance from the cluster centre. By targeting one-quarter of the households, with selective indoor spraying or other house-protection measures, malaria incidence could be reduced by more than two-thirds in this community.
Sujet(s)
Paludisme à Plasmodium falciparum/épidémiologie , Paludisme à Plasmodium vivax/épidémiologie , Adolescent , Adulte , Sujet âgé , Sujet âgé de 80 ans ou plus , Brésil/épidémiologie , Enfant , Enfant d'âge préscolaire , Méthodes épidémiologiques , Femelle , Humains , Nourrisson , Nouveau-né , Paludisme à Plasmodium falciparum/prévention et contrôle , Paludisme à Plasmodium vivax/prévention et contrôle , Mâle , Adulte d'âge moyen , Plasmodium falciparum/isolement et purification , Plasmodium vivax/isolement et purification , Réaction de polymérisation en chaîne , Santé en zone rurale , Jeune adulteRÉSUMÉ
Temporal changes in the prevalence of antigenic variants in Plasmodium falciparum populations have been interpreted as evidence of immune-mediated frequency-dependent selection, but evolutively neutral processes may generate similar patterns of serotype replacement. Over 4 years, we investigated the population dynamics of P. falciparum polymorphisms at the community level by using 11 putatively neutral microsatellite markers. Plasmodium falciparum populations were less diverse than sympatric P. vivax isolates, with less multiple-clone infections, lower number of alleles per locus and lower virtual heterozygosity, but both species showed significant multilocus linkage disequilibrium. Evolutively neutral P. falciparum polymorphisms showed a high turnover rate, with few lineages persisting for several months in the population. Similar results had previously been obtained, in the same community, for sympatric P. vivax isolates. In contrast, the prevalence of the 2 dimorphic types of a major antigen, MSP-2, remained remarkably stable throughout the study period. We suggest that the relatively fast turnover of parasite lineages represents the typical population dynamics of neutral polymorphisms in small populations, with clear implications for the detection of frequency-dependent selection of polymorphisms.