Epidemiological aspects of Toxoplasma gondii infection in riverside communities in the Southern Brazilian Amazon

INTRODUCTION: Toxoplasma gondii infection is widely prevalent in humans and other animals worldwide. Information on the prevalence of T. gondii infection is scarce in some regions of Brazil, including riverside communities along the Amazon River basin. M METHODS: The prevalence of T. gondii in 231 people, aged 1-85 years, who were living in four riverside communities along the Purus River, Lábrea, State of Amazonas, Brazil, was determined. Antibodies against T. gondii were assayed using a commercial enzyme-linked immunosorbent assay (ELISA) kit. The hearts and brains of 50 chickens, which were raised free-range in the communities, were pooled according to the community of origin and bioassayed in mice. The isolates were genotyped using polymorphisms at 12 nuclear markers (SAG1, 5' and 3'-SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico and CS3). RESULTS: The overall seroprevalence of T. gondii was 56.7% (131/231). IgG antibodies were presented by 117 (89.3%) and IgM by 14 (10.7%) of the 131 positive individuals. No association between age group and gender with prevalence was observed (chi-square test, p > 0.05); however, the comparison between localities showed that the seroprevalence of T. gondii was significantly lower among the individuals living in the Boca do Ituxi (p < 0.05) community. Five isolates of T. gondii were obtained in the mouse bioassay, and genotyping revealed two complete genotypes that had not been described previously and three mixed isolates. CONCLUSIONS: These results support previous findings that T. gondii population genetics are highly diverse in Brazil and that T. gondii infection is active in these riverside communities. .

New records of Mansonella ozzardi: a parasite that is spreading from the state of Amazonas to previously uninfected areas of the state of Acre in the Purus River region

Mansonella ozzardi infections are common in the riverside communities along the Solimões, Negro and Purus Rivers in the state of Amazonas (AM). However, little is known about the presence of this parasite in communities located in regions bordering AM and the state of Acre. The prevalence rate of M. ozzardi infections was determined in blood samples from volunteers according to the Knott method. A total of 355 volunteers from six riverine communities were enrolled in the study and 65 (18.3%) were found to be infected with M. ozzardi. As expected, most of the infections (25%) occurred in individuals involved in agriculture, cattle rearing and fishing and an age/sex group analysis revealed that the prevalence increased beginning in the 40-50-years-of-age group and reached 33% in both sexes in individuals over 50 years of age. Based on the described symptomatology, articular pain and headache were found to be significantly higher among infected individuals (56 and 65% prevalence, respectively, p < 0.05). Sera from volunteers were subjected to ELISA using a cocktail of recombinant proteins from Onchocerca volvulus to evaluate the specificity of the test in an endemic M. ozzardi region. No cross-reactions between M. ozzardi-infected individuals and recombinant O. volvulus proteins were detected, thus providing information on the secure use of this particular cocktail in areas where these parasites are sympatric.

Richness and composition of macrophyte assemblages in four Amazonian lakes / Riqueza e composição da assembleia de macrófitas em quatro lagos amazônicos

Aquatic macrophytes are an important component in the structure of lakes in Neotropical floodplains, for example, because they support a high diversity of invertebrates and vertebrates. In this paper, we tested whether or not the variability of macrophyte assemblages is lower in spatially close quadrats than among quadrats of different lakes. The study was carried in four lakes in a large Amazonian floodplain (Purus river), where floating meadows were investigated. A total of 49 taxa of macrophytes were found. Five species dominated and three species were rare. Taxa richness, composition and beta diversity differed more between than within lakes. Because high beta diversity was found among the lakes, they should be considered individually important for maintaining the gamma diversity of macrophytes within the Purus River floodplain, and this should be considered in plans of lake management.

As macrófitas aquáticas são um importante componente para a estrutura de lagos neotropicais em planícies de inundação, porque suportam alta diversidade de invertebrados e vertebrados. Neste trabalho, nós testamos se a variabilidade da assembleia de macrófitas aquáticas é menor entre "quadrats" espacialmente próximos do que "quadrats" em lagos diferentes. O estudo foi desenvolvido em quatro lagos da planície amazônica (rio Purus), onde bancos flutuantes de macrófitas foram amostrados. Um total de 49 taxa de macrófitas foi encontrado. Cinco espécies dominaram e três espécies foram raras. A riqueza de taxa, composição e diversidade de espécies diferiram mais entre os lagos do que dentro dos lagos. Pela alta diversidade beta encontrada nos lagos, esses lagos devem ser considerados importantes individualmente para manter a diversidade gamma de macrófitas dentro da planície de inundação do rio Purus. Esse fato deve ser considerado em planos de manejo desses lagos de planície.

Aspectos ecológicos e epidemiológicos de acidentes ofídicos em comunidades ribeirinhas do baixo rio Purus, Amazonas, Brasil

Snakebites were registered in 10 riverside communities of the lower Purus River through interviews with the victims. Local inhabitants answered questions about their perception on ecological aspects of snakes species involved in snakebites. Snake size and bite height on the victim body were estimated with measuring tape. Correspondence of local names and scientific species were obtained by using descriptions and images of the snakes. Additional data on the number of families with snakebites victims were obtained from social-economic surveys for other 17 communities in the Piagaçu Purus Reserve. Eighteen people and 28 snakebites events were registered in five communities. The number of victims per community was not related to population's size. The number of families with victims was higher in larger communities (r²= 0.444; p= 0.003). Approximately 88% of snakebites were inflicted on the lower limbs of the victims. There was no relationship between estimated snake's size and the height of the bite. Most snakebites occurred at daytime (82.14%), and during the high rive period (64.28%) that coincides with the extraction of brazil nut and timber by the local people when they spend more time in the forest. Only one death due to snakebite was registered. The species Bothrops atrox was responsible for most of the accidents in the region. Snake's identification by local people revealed various synonymies, with 20 local names attributed to 33 species. In their perception, B. atrox and Lachesis muta were the most dangerous species and differ in attack behavior.

Acidentes ofídicos foram registrados em dez comunidades ribeirinhas do baixo rio Purus através de entrevista às vítimas. Os ribeirinhos responderam perguntas sobre a percepção ambiental da ecologia das serpentes envolvidas nos acidentes. O tamanho das serpentes e a altura da mordida no corpo foram estimados com fita métrica. A correspondência entre os nomes locais e científicos das serpentes foi levantada utilizando descrições e imagens das espécies. Para outras 17 comunidades dados adicionais do número de famílias com vítimas de acidentes ofídicos foram avaliados através do diagnóstico sócio-ambiental da Reserva de Desenvolvimento Sustentável Piagaçu-Purus. Foram entrevistados 18 ribeirinhos e registrados 28 acidentes ofídicos em cinco comunidades. O número de vítimas por comunidade não teve relação com o tamanho da população. O número de famílias com vítimas foi maior em comunidades maiores (r²= 0,444; p= 0,003). Aproximadamente 88% das mordidas foram nos membros inferiores. Não houve relação do tamanho estimado da serpente com a altura da mordida. A maioria dos acidentes ocorreu de dia (82,14%) e no período de cheia (64,28%) na época de exploração da castanha-da-Amazônia e da madeira pelos ribeirinhos, atividades que despendem maior tempo na floresta. Um único caso de morte por acidente ofídico foi registrado. A serpente Bothrops atrox foi à espécie mais relacionada com acidentes na região. O reconhecimento das serpentes pelos ribeirinhos revelou várias sinonímias, com 20 nomes locais atribuídos a 33 espécies. Na percepção dos ribeirinhos as serpentes B. atrox e Lachesis muta foram às espécies mais temidas e diferem no comportamento de ataque.

Influência da precipitação na qualidade da água do Rio Purus / Impacts of precipitation on the water quality of the Purus River

Os impactos da precipitação na qualidade da água ao longo do rio Purus, localizado no estado do Amazonas, foi investigado por meio de dados de precipitação, estimada por satélites, e informações sobre a temperatura da água, condutividade, pH, turbidez, oxigênio dissolvido e sólidos suspensos totais, adquiridas em quatro diferentes áreas ao longo do rio. Os resultados mostraram correlação negativa entre precipitação e turbidez e positiva entre precipitação e temperatura, condutividade, oxigênio dissolvido, sólidos suspensos totais e pH. O uso do solo, juntamente com o regime de precipitação, parecem ser os fatores principais que determinam a qualidade da água nos pontos de amostragem.

The impacts of precipitation on the water quality along the Purus River, located in the Brazilian State of the Amazonas, was investigated using data of precipitation estimated by satellite and information about water temperature, conductivity, pH, turbidity, dissolved oxygen and total suspended solids. The data were acquired in four different areas along the river. The results showed negative correlation between precipitation and turbidity. They also showed positive correlation between precipitation and temperature, conductivity, dissolved oxygen, total suspended solids and pH. The land use together with the rainfall regime seems to be the main sources of impact on the water quality around the sampling places.