Urban and suburban malaria in Rondônia (Brazilian Western Amazon) II. Perennial transmissions with high anopheline densities are associated with human environmental changes.
Longitudinal entomological surveys were performed in Vila Candelária and adjacent rural locality of Bate Estaca concomitantly with a clinical epidemiologic malaria survey. Vila Candelária is a riverside periurban neighborhood of Porto Velho, capital of the state of Rondônia in the Brazilian Amazon. High anopheline densities were found accompanying the peak of rainfall, as reported in rural areas of the region. Moreover, several minor peaks of anophelines were recorded between the end of the dry season and the beginning of the next rainy season. These secondary peaks were related to permanent anopheline breeding sites resulting from human activities. Malaria transmission is, therefore, observed all over the year. In Vila Candelária, the risk of malaria infection both indoors and outdoors was calculated as being 2 and 10/infecting bites per year per inhabitant respectively. Urban malaria in riverside areas was associated with two factors: (1) high prevalence of asymptomatic carriers in a stable human population and (2) high anopheline densities related to human environmental changes. This association is probably found in other Amazonian urban and suburban communities. The implementation of control measures should include environmental sanitation and better characterization of the role of asymptomatic carriers in malaria transmission.
Gil
Luiz Herman Soares
LH
Instituto de Pesquisa em Patologias Tropicais, Porto Velho, RO, Brasil. herman@iapepatro.org.br
Tada
Mauro Shugiro
MS
Katsuragawa
Tony Hiroshi
TH
Ribolla
Paulo Eduardo Martins
PE
da Silva
Luiz Hildebrando Pereira
LH
D000818:Animals; D000852:Anopheles / Q000145:classification*; D001938:Brazil / Q000453:epidemiology; D005260:Female; D006801:Humans; D007303:Insect Vectors / Q000145:classification*; D008137:Longitudinal Studies; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D016780:Malaria, Vivax / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D011156:Population Density; D011157:Population Dynamics; D011159:Population Surveillance; D012621:Seasons; D013383:Suburban Population; D014505:Urban Population