An epidemic of sylvatic yellow fever in the Southeast region of Maranhao State, Brazil, 1993-1994: epidemiologic and entomologic findings

• Autor(a) principal: Vasconcelos, Pedro Fernando da Costa
• Data de Publicação: 1997
• Outros Autores: Rodrigues, Sueli Guerreiro, Dégallier, Nicolas, Moraes, Mário Augusto Pinto de, Rosa, Jorge Fernando Soares Travassos da, Rosa, Elizabeth Salbé Travassos da, Mondet, Bernard, Barros, Vera Lúcia Reis Souza de, Rosa, Amélia Paes de Andrade Travassos da
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Digital do Instituto Evandro Chagas (Patuá)
• Texto Completo: https://patua.iec.gov.br/handle/iec/874
• topic: Febre Amarela / epidemiologia; Febre Amarela / mortalidade; Febre Amarela / transmissão; Culicidae / virologia; Surtos de Doenças; Vírus da Febre Amarela / isolamento & purificação; Estudos Soroepidemiológicos; Vacinação; Incidência

Yellow fever virus transmission was very active in Maranhao State in Brazil in 1993 and 1994. An investigation was carried out to evaluate the magnitude of the epidemic. In 1993, a total of 932 people was examined for yellow fever from Maranhao: 70 were positive serologically, histopathologically, and/or by virus isolation, and another four cases were diagnosed clinically and epidemiologically. In Mirador (17,565 inhabitants), the incidence was 3.5 per 1,000 people (case fatality rate [number of deaths/number of cases diagnosed] = 16.4 percent), while in a rural yellow fever risk area (14,659 inhabitants), the incidence was 4.2 and the case-fatality rate was 16.1 percent (10 of 62). A total of 45.2 percent (28 of 62) asymptomatic infections were registered. In 1994, 49 serum samples were obtained and 16 cases were confirmed (two by virus isolation, two by seroconversion, and 12 by serology). No fatal cases were reported. In 1993, 936 potential yellow fever vectors were captured in Mirador and a single strain was isolated from a pool of Haemagogus janthinomys (infection rate = 0.16 percent). In 1994, 16 strains were isolated from 1,318 Hg. janthinomys (infection rate = 1.34 percent) and one Sabethes chloropterus (infection rate = 1.67 percent). Our results suggest that this was the most extensive outbreak of yellow fever in the last 20 years in Brazil. It is also clear that the lack of vaccination was the principal reason for the epidemic, which occurred between April and June, during the rainy season, a period in which the mosquito population in the forest increases.