Epidemiologia da malária em comunidades do rio Padauiri, médio rio Negro, uma área de extrativismo vegetal da piaçaba no estado de Amazonas,Brasil. / Epidemiology of the malaria in communities of the river Padauiri, medium Black river, an area of vegetal extraction of piaçaba in the State of Amazon, Brazil.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The Padauiri River - a tributary of Rio Negro in the Amazonas state - is a piaçaba extraction area located in a high endemic malaria region. In this study, an investigation of the local epidemiology, which has not been previously reported, was accomplished. In order to establish Plasmodium infection prevalence, malaria new cases and to determine risk factors we conducted a cohort study (n=188) after carrying out basic epidemiology researches in that area (a retrospective analysis and a cross-sectional study). Following a questionnaire and physical examination of all local inhabitants, blood samples were collected for carrying out thick and thin smears, DNA extraction for molecular diagnosis and serological probes. Simultaneously, entomological studies were conducted to figure out the main vectors and their behavioral. Breeding water collections were also searched for in the surrounding forest. Malaria case was defined as the patients presenting signs and symptoms of malaria disease with at least one of the human Plasmodium parasite determined by thick smear. Asymptomatic infection was defined as carriers of Plasmodium parasite - observed by thick smear and/or positive PCR - without presenting symptoms before or after 30 days of the blood sample collection. Asymptomatic carriers could not have used antimalarial drugs in the last 30 days before blood collection. During the follow-up period, any death or hospital admission caused by malaria was registered in the area in the cohort. A total of 53.2% (100/188) of inhabitants had malaria with 169 malaria episodes. The Annual Parasitic Incidence (API) was 602.3 / 1000 inhabitants. The mean of malaria episodes was 1.7. Children <5 years old showed higher risk for disease compared with older people (RR: 1.64, CI95%=1.26- 2.14, p=0.012). The mean of malaria episodes in those children was 2.2. P. vivax was the main parasite detected in this cohort, which showed an epidemiology changing pattern. Interestingly, P. falciparum was the prevalent parasite in the last decade. We found asymptomatic Plasmodium infections (both P. vivax and P. falciparum) ranging from 8.2 to 24.0%. The clinical malaria episodes were seasonal with a trend to occur in the beginning and end of the rainy season. Asymptomatic infection was more frequent in the dry season. The most important insect vector in the studied area was the Anopheles darlingi with epidemiological regional differences. The probability of capture the vector was higher in the piaçabas areas. In this place of the Amazonian region, An. darlingi has predominantly endofagic behavioral. The main determinant risk for parasite transmission was geographical localization. The population living in localities near at the piaçaba collocations had more malaria cases and asymptomatic Plasmodium infections. Likewise, An. darlingi was found inside of the dwellings although permanent breeding water collection was not observed in the surrounding area. On the other hand, only temporary breeding water collections were found with anophelines immature phases. We observed differences in the malaria prevalence and asymptomatic Plasmodium infection along the few kilometers within the researched area. Diverse malaria situations were observed in a small geographical space limiting the control strategies. It is crucial to apply different malaria control strategies for each transmission area.

ASSUNTO(S)

doencas infecciosas e parasitarias plasmodium vivax malária plasmodium falciparum comunidades pequenas plasmodium falciparum plasmodium vivax small communities malaria

ACESSO AO ARTIGO

Documentos Relacionados