Arboviruses Pathogenic for man in Brazil

Os mais importantes aspectos clinicicos e ecoepidemiologicos e aspectos preventivos acerca das arboviroses associadas com doenca humana no Brasil sao discutidos.Trinta e seis arbovirus dentre os tipos presentemente isolados no Pais tem sido incriminados como causadores de doenca humana. Destes, cinco sao importantes em termos de saude publica pois estao associados com epidemias , sao os virus Dengue (DEN), Mayaro(MAY), Oropouche (ORO), Rocio (ROC) e Febre amarela (FA). DEN e ORO estao associados com doenca humana epidemica em areas urbanas enquanto MAY, ROC e FA especialmente em areas rurais. Basicamente, o virus ORO determina um quadro febril algumas vezes acmpanhado por meningite asseptica. MAY e DEN sao responsaveis por quadros exantematicos, sendo que DEN, nos ultimos anos tem sido associado com quadros de febre hemorragica, o que sabidamente e o mecanismos pelo qual o virus FA determinaa sua apresentacao clinica classica e o ROC esta associado com graves quadros de encefalite. Trinta e um outros arbovirus tem sido associados com doenca febril benigna em poucos e esporadicos casos. Afora DEN e os Arenavirus Flexal e Sabia ( nao sao arbovirus), todos os arbovirus envolvidos com doenca humana na AmazoniaBrasileira, sao mantidos em natureza atraves de um ciclo silvestre desenvolvido na floresta, onde diversas especies de insetos hematofagos e vertebrados silvestres atuam como vetores e hospedeiros, respectivamente.O virus DEN tem um ciclo urbano em que o mosquito Aedes aegypti e o vetor e o homem atua como hospedeiro. Os arenavirus sao transmitidos diretamente ao homen atraves de excretas de roedores que sao seus principais hospedeiros.Excetuando os cinco virus associados com epidemias que causam um grande impacto socio-economico, inclusive levando a morte, casos verificados com FA, DEN e ROC, o verdadeiro papel dessesvirus como agentes sistematicos de doencas humanas e ainda puco conhecido. Novos estudos sao necessarios para esclarecer aspectos ainda obscuros acerca da epidemiologia da maioria desses arbovirus

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

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