The frist laboratory confirmed cases of dengue fever in Brazil: virus isolation and sorological results

Investigation of an extensive outbreak of febrile illness in the city of Boa Vista, Roraima State, Brazil, that began in late 1981 lasted until August 1982, established that dengue virus was incriminated in the etiology. Virological studies were madeon 31 selected patients, dengue virus (types 1 and 4) was isolated in 12 of them. The virus (both types) was also isolated from three of 51 pools (1,478 mosquitoes) of Aedes aegypti captured especially downtown. To isolate the virus, allthe material was inoculatedin Aedes albopictus cells (C6/36) and in suckling mice, and virus isolates were identified by the indirect immunofluorescence usingthe monoclonal antibodies. The results of hemagglutination inhibition and complement fixationtest with 27 paired acute convalescent phase sera and 359 single convalescent or contacts sera were highly suggestive of dengue etiology.The clinical features were those os classical dengue fever. Later, afterthe outbreak, serological survey involving899 sera was conducted in order to determine the extent of the epidemic. The results indicated that at 11,000 dengue cases ocurred. These are the first laboratory confirmed cases of dengue fever in Brazil

Entomological studies on Dengue fever vectors in Brazil: the epidemics of Boa Vista, Roraima, 1982, Niteroi, Rio de Janeiro, 1986, and Ceara State, 1986, 1994

No Brasil, o virus deo dengue é transmitido pelo mosquito urbano Aedes Aegypti. Foi na ocasiäo dos primeiros isolamentos realizados a partir de casos humanos em Boa Vstas (RR) que o virus foi também isolado - sorotipos DEN 1 (1 amostra) e DEN 4 (2 amostras) - a partir de mosquitos naturalmente infectados. Durante o segundo episódio epidêmico, em Niterói (RJ) , foram isoladas 3 amostras de DEN 1 a partir de mosquitosfêmeas coletadas com isca humana ou em repouso. Durante essa epidemia, nos locais nâo tratados por inseticidas, o índice de Breteau era de 102. A dissecaçäo de uma amostragen dos mosquitos mostrou que (1) as fêmeas agressivas eram mais velhas que as coletadas em repouso, (2) a proporçäo de repastos interrompidos ou múltiplos era elevada. Inquéritos entomológicos foram realizados durante as epidemias de 1986 e 1994 no Ceará. Tres amostras de DEN 1 e 16 amostras de DEN 2 foram isoladas a partir de AE. aegypti coletados em Cascavel e Caucaia, respectivamente. A suscetibilidade à infecçäo oral dos mosquitos sobre os pacientes com viremia pelo virus DEN 2 foi testada. Positividade dos mosquitos apareceu a partir do terceiro dia após repasto. 44 por cento dos mosquitos form infectados após ter sido alimentados com sangue contendo um título de virus ( Log TCD 50) igual a 3,5 . Tentativas de isolamento a partir de mosquitos machos, imaturos ou outras espécies foram negativas

A recente outbreak of yellow fever in south of Maranhäo State, Brazil: epidemiological, clinical and entomological findings

An outbreak of Yellow fever virus (YF) ocorred in Maranhäo State in 1993 (Barra do Corda, Esperantinopolisand Mirador) and 1994 (Pastos Bons), where several cases were reported. In 1993 a total of 932 people was examined for YF distributedas follows: 32 from Barra do Corda, 26 from Esperantinópolis and 874 from Mirador. From these, 70 cases were YF confirmed serologically (IgM capture MAC ELISA), histopathologically and/or by virus isolation. Another 4 cases diagnosed clinically and epidemiologically, brougth the total to 74 (Barra do Corda:5; Esperantinópolis:7 and Mirador: 62). The age of patients ranged from 2 to 71 years old (mean: 24):32 (43.2 percent) were female and 42 (56.8 percent) male and total lethality-rate was 17.5 percent (13/74). In Mirador ( 17,565 inhabitants), where an intesive survey was carried out, the incidence was 3,5 per 1,000 people, but in the rural YF risk area (14,695 inhabitants) the incidence was 4.2, and the mortality 16.1 percent (10/62). A total of 45.2 percent (28/62) asymptomatic infections were registered. In 1994, a total of 49 serum samples was obtained, 2 by virus isolation, 2 by seroconversion and 12 by serology. On the other hand, no fatal cases were reported in Pastos Bons. In 1993 , 936 potential YF vectors were captured in Mirador and a single strain was isolated from a pool of Haemagogus janthinomys (infection rate (IR): 0.16 percent). In 1994, 16 strains were isolated from 1,318 Hg. janthinnomys (IR: 1.34 percent) and one Sabethes chloropterus (IR:1.67 percent). Our results suggest that this was the most extensive outbreak of YF in the last 20 years in Brazil

Estudos sorológicos para pesquisa de anticorpos de arbovírus em populaçäo humana da regiäo do Vale do Ribeira: IV. Inquérito em escolares residentes no município de Iguape, SP (Brasil) / Serological studies for research of arbovirus antibodies in a human population of the Ribeira Valley region: IV. Survey in school children residents in the Iguape county, SP (Brazil)

Relatam-se os resultados de inquérito sorológico para pesquisa de anticorpos de 17 arbovírus em 337 escolares de 6 a 14 anos de idade, residentes em quatro áreas, com diferentes características ecológicas, situadas no município de Iguape, Vale do Ribeira, do Estado de Säo Paulo (Brasil): 1 - zona urbana da cidade de Iguape; 2 - Rocio, bairro periférico com características rurais; 3 - zona de cultura extensiva de banana, na planície litorânea; 4 - zona de mata primitiva na regiäo pré-serrana. Observou-se, em 8,31% dos investigados, a presença de anticorpos inibidores de hemaglutinaçäo de arbovírus dos grupos antigênicos A, B, C, Bunyamwera, Simbu e Anopheles A. Evidenciou-se diferença significante na proporçäo dos soros positivos entre escolares residentes nas zonas de bananal e de mata (19,05% e 16,67%) e moradores na zona urbana e no bairro do Rocio (1,89% e 3,81%). Crianças sempre residentes na zona urbana de Iguape, sem hábito de freqüência e ambiente silvestre, apresentaram anticorpos neutralizantes para os vírus Caraparu e Rocio, sugerindo transmisäo urbana desses agentes. Näo há indícios sorológicos de infecçöes recentes causadas pelo flavivírus Rocio