Jorge F. S Travassos da Rosa

Inadequate management of natural ecosystem in the Brazilian Amazon region results in the emergence and reemergence of arboviruses

A total of 187 different species of arboviruses and other viruses in vertebrates were identified at the Evandro Chagas Institute (IEC) from 1954 to 1998, among more than 10,000 arbovirus strains isolated from humans, hematophagous insects, and wild and sentinel vertebrates. Despite intensive studies in the Brazilian Amazon region, especially in Pará State, very little is known about most of these viruses, except for information on date, time, source, and method of isolation, as well as their capacity to infect laboratory animals. This paper reviews ecological and epidemiological data and analyzes the impact of vector and host population changes on various viruses as a result of profound changes in the natural environment. Deforestation, mining, dam and highway construction, human colonization, and urbanization were the main manmade environmental changes associated with the emergence and/or reemergence of relevant arboviruses, including some known pathogens for humans.

Epidemia de dengue em Fortaleza, Ceará: inquérito soro-epidemiológico aleatório

OBJETIVO: Seguindo-se a epidemia de dengue (DEN), em 1994, em Fortaleza, Ceara, causada pelo sorotipo 2 (DEN-2), realizou-se inquerito soro-epidemiologico aleatorio para avaliar e dimensionar o impacto da mesma e a prevalencia do dengue por distrito sanitario. METODO: Foi aplicado questionario contendo informacoes gerais, condicoes socio-economicas, informacoes sobre o quadro clinico e tempo de doenca. A amostra foi calculada para estimar uma prevalencia de 20%, com erro relativo de 10%, e intervalo de confianca de 95% (erro a de 5%). O sorteio e as analises foram realizadas por meio de computador usando programas apropriados. RESULTADOS E CONCLUSOES: Foram colhidas 1.341 amostras de soro de 9 distritos sanitarios, testadas por inibicao da hemaglutinacao, sendo classificadas como negativas e positivas (respostas primaria - RP e secundaria - RS). Foram reativas 588 (44%) amostras, sendo 93 (7%) RP e 495 (37%) RS. A prevalencia global em Fortaleza variou de 21% a 71%. Houve 41% (243/588) de infeccoes assintomaticas (IA) e 59% (346/588) sintomaticas (IS). Nao houve diferenca da prevalencia quanto ao sexo, faixa etaria e escolaridade, ao contrario da condicao socioeconomica que apresentou diferencas estatisticamente significantes (p < 0,001). Ocorreram mais IA (p<0,001) e IS (p<0,0001) em casos de RS que RP, com significância estatistica em ambos os sexos. Os sintomas mais prevalentes no casos confirmados foram febre, cefaleia, mialgias, exantema, mal estar geral, tontura e artralgias, sendo que prurido, dor ocular, exantema e gengivorragia foram estatisticamente significantes (p<0,005). Tontura e artralgias foram mais associados com RS que com RP, havendo diferencas estatisticas (p <0,05).OBJECTIVE A seroepidemiological random survey was carried out in Fortaleza city, State of Ceará, Brazil, following an epidemic of dengue virus type 2 (DEN 2), with the purpose of evaluating the frequency of clinical manifestations (signs and symptoms) and the prevalence of dengue infection. METHOD A questionnaire calling for information on address, sex, age, clinical, epidemiological and economic status was applied to the population, followed by venupuncture collection of 5-10 ml of blood for testing by hemagglutination-inhibition (HI). The sample was calculated to obtain a prevalence of 20% with relative risk of 10% and confidence interval of 95%. All information obtained was analyzed by computer using Epi Info 5.0, Lotus 123, Excel 5.0, and Stata software. RESULTS AND CONCLUSIONS A total of 1,341 serum samples were obtained from nine Health Districts (SD) and tested by hemagglutination inhibition. Of these, 589 (44%) were positive and 752 (56%) negative. Of the positive results, 93 primary responses (PR) (7%) to DEN-2 and 496 secondary responses (SR) (37%) were observed. The global prevalence in the SD ranged from 21% to 71%. There were 41% (243/589) asymptomatic infections and 59% (346/589) symptomatic infections. Data analysis showed no difference in frequency by sex, age, on schooling, although a highly statistically significant difference was found as between the different social classes, the infection most commonly observed being among people of better social status. The stratification of positive cases showed greater prevalence of AI (p < 0.001) and SI (p < 0.0001) in both sexes, among people with SR rather than PR. The most prevalent symptoms were fever, headache, muscle pains, rash, dizziness, and joint pains. Moreover, itching, retro-bulbar pain, rash, and gingival bleeding, showed statistically significant differences. On the other hand, dizziness and joint pains were more associated in the patients with SR than PR, and statistically significant differences were also observed.

Epidemiologia das encefalites por arbovirus na Amazonia brasileira

An overview of ecological, epidemiological and clinical findings of potential arthropod-borne encephalitis viruses circulating in the Amazon Region of Brazil are discussed. These viruses are the Eastern Equine Encephalitis (EEE), Western Equine Encephalitis (WEE), St. Louis Encephalitis (SLE), Mucambo (MUC) and Pixuna (PIX). These last two are subtypes (HI and IV) of Venezuelan Equine Encephalitis virus. The areas of study were the highways and projects of development, as well as places where outbreaks of human diseases caused by arboviruses had been detected. These viruses are widespread in all Amazonia, and at least four of them, EEE, WEE, SLE and MUC are pathogenic to man. EEE and WEE infections were detected by serology, while SLE and MUC by either serology and virus isolation. The PIX virus has the lowest prevalence and, it was isolated in only a few cases, one being from a laboratory infection. Wild birds are the main hosts for all these viruses, except MUC, whose major hosts are rodents. The symptoms presented by infected people were generally a mild febrile illness. Although, jaundice was observed in two individuals from whom SLE was isolated. A comparison of the clinical symptoms presented by the patients in the Amazon Region and other areas of America, especially in the USA is made. In Brazilian Amazon region epidemics have not been detected although, at least, one EEE epizootic was recorded in Braganca, Para State, in 1960. At that time, of 500 horses that were examined 61% were positive to EEE by HI and of mem 8.2% died On the other hand. SLE has caused four epizootics in a forest near Belem. Wild birds and sentinel monkeys were infected, but no human cases were reported.

Inquérito soro-epidemiológico na Ilha de São Luis durante epidemia de dengue no Maranhão

The Island of Sao Luis in the State of Maranhao, constituted by the municipalities of Sao Luis - SL (835,428 inhabitants), Sao Jose de Ribamar - SJR (60,633 inhabitants) and Paco do Lumiar - PL (80,274 inhabitants), has been suffering dengue (DEN) fever epidemics since 1995, caused by DEN-1. In 1996, from August through October, an aleatory sero-epidemiologic survey was carried out in order to estimate the incidence of DEN infection and to analyze other clinical and epidemiological parameters. A questionnaire was applied and serum samples were simultaneously obtained. Serum samples were tested by hemagglutination inhibition (HI). Results were analyzed using Lotus123, Epi-info 6.0, Excel 5.0 and STATA softwares. A total of 1,217 serum samples were obtained (101 of PL, 100 of SJR and 1017 of SL). The rate of DEN was 55.4% in PL, 28% in SJR and 41.4% in SL, suggesting the occurrence of 401,933 infections. No difference was seen between males and females, but infection occurred more in the upper social class than in poor people (p < 0.003), and was more frequent in adults than in children (p < 0.0004). In SL, the incidence was stratified into seven sanitary districts (SD), and prevalence was found to range from 26.1% in SD4 to 56.8% in SD1 (p < 0.0001). Symptoms were more frequently reported by people whose HI was positive: they included fever, headache, chills, dizziness, retrobulbar pains, muscle and joint pains, nausea, anorexia and skin rash. In spite of the high incidence of infection, no hemorrhagic cases were reported.The island of São Luis in the State of Maranhão, constituted by the municipalities of São Luis-SL (835,428 inhabitants), São José de Ribamar-SJR (60,633 inhabitants) and Paço do Lumiar-PL (80,274 inhabitants), has been suffering dengue (DEN) fever epidemics since 1995, caused by DEN-1. In 1996, from August through October, an aleatory sero-epidemiologic survey was carried out in order to estimate the incidence of DEN infection and to analyze other clinical and epidemiological parameters. A questionnaire was applied and serum samples were simultaneously obtained. Serum samples were tested by hemagglutination inhibition (HI). Results were analyzed using Lotus 123, Epi-info 6.0, Excel 5.0 and STATA softwares. A total of 1,217 serum samples were obtained (101 of PL, 100 of SJR and 1017 of SL). The rate of DEN was 55.4% in PL, 28% in SJR and 41.4% in SL, suggesting the occurrence of 401,933 infections. No difference was seen between males and females, but infection occurred more in the upper social class than in poor people (p < 0.003), and was more frequent in adults than in children (p < 0.0004). In SL, the incidence was stratified into seven sanitary districts (SD), and prevalence was found to range from 26.1% in SD4 to 56.8% in SD1 (p < 0.0001). Symptoms were more frequently reported by people whose HI was positive: they included fever, headache, chills, dizziness, retrobulbar pains, muscle and joint pains, nausea, anorexia and skin rash. In spite of the high incidence of infection, no hemorrhagic cases were reported.

Epidemia de febre classica de dengue causada pelo sorotipo 2 Em Araguaina, Tocantins, Brasil

Registramos a ocorrencia de epidemia de dengue causada pelo sorotipo 2 (DEN 2) na cidade de Araguaina, estado do Tocantins (TO) situado no Brasil central. Quatrocentos individuos de 74 familias, residentes nos bairros S. Joao, Araguaina Sul e Neblina foram entrevistados e sangrados, independentemente de terem adoecido ou nao. Os soros tanto de adultos quanto de criancas de ambos os sexos foram usados para pesquisa de anticorpos inibidores da hemaglutinacao (IH) e IgM atraves de ensaio imunoenzimatico (MAC ELISA). Nas casas onde haviam doentes no momento do inquerito, sangue total tambem foi colhido para tentativa de isolamento de virus. O quadro clinico apresentado pelos pacientes foi caracterizado por febre, cefaleia, mialgias, artralgias e exantema do tipo maculo-papular nao pruriginoso. A infeccao foi mais frequente em mulheres (33.9%) do que nos homens (23.8%), ocorrendo em todas as faixas etarias, inclusive em criancas com menos de um ano de idade, bem como em maiores de 70 anos. Um total de 1105 mosquitos (56 femeas e 45 machos de Culex quinquefasciatus e 567 femeas e 437 machos de Aedes aegypti) foram obtidos a partir de larvas coletadas em Araguaina. As femeas de Ae. aegypti obtidas das larvas fizeram repasto sanguineo em 8 pacientes febris. O diagnostico laboratorial foi feito por isolamento de virus (cultura de celulas de Aedes albopictus, clone C6/36) e por sorologia (IH e MAC ELISA). Foram isoladas 5 amostras de DEN 2 de pacientes febris e tipadas por imunofluorescencia indireta usando anticorpos monoclonais de dengue. Nenhuma amostra viral foi isolada de mosquitos. Outrossim, comprovou-se infeccao em 111 pessoas sangradas, o que revelou um indice de positividade de 27.75% (111 em 400), sendo que 66.2% das familias estudadas apresentaram pelo menos um individuo positivo. Ocorreram ainda, 26.1% de infeccoes assintomati-cas. Por outro lado, a correlacao de positividade entre os dois testes usados (IH e MAC ELISA) foi de 94.6%. Estimamos que ocorreram aproximadamente 83.250 casos da doenca, entre 15 de marco a 31 de maio de 1991. Esta e a primeira epidemia de DEN 2 em um estado da Amazonia Brasileira, portanto em area endemica de febre amarela, e a primeira evidencia da interiorizacao do DEN 2, ate entao restrito ao Rio de Janeiro.We report the first outbreak of dengue fever caused by dengue 2 (DEN 2) in Araguaina, Tocantins State. Four hundred people of 74 families, living at S. João, Araguaina Sul and Neblina districts were questioned and then bled, in order to obtain sera to test for anti-dengue antibodies. If a person was sick, a small quantity of blood was collected for virus isolation. The main clinical picture of disease was characterized by fever, headache, myalgias, arthralgias and skin rash. Were obtained 1,105 (56 females and 45 males of Culex quinquefasciatus and 567 females and 437 males of Aedes aegypti) mosquitoes from larvae collected in Araguaina. The females of Aedes aegypti obtained from larvae were allowed to feed on 8 febrile patients. The diagnosis of infection was made by both virus isolation into Aedes albopictus (C6/36) cells, and serology, by Hemagglutination-inhibition (HI) and IgM capture ELISA (MAC ELISA). No virus was isolated from mosquitoes. Although five strains of DEN 2 were obtained from humans, and another 111 infections were diagnosed serologically (IgM positive). The positivity rate of the samples was 27.75% (111 of 400), while that of the families was 66.2% (45 of 72), where at least one member of the each family was infected. It was also detected 26.1% of asymptomatic infections. All age groups were affected. Therefore, the infection was more frequent in females (33.5%) than males (23.8%).(ABSTRACT TRUNCATED AT 250 WORDS)Registramos a ocorrencia de epidemia de dengue causada pelo sorotipo 2 (DEN 2) na cidade de Araguaina, estado do Tocantins (TO) situado no Brasil central. Quatrocentos individuos de 74 familias, residentes nos bairros S. Joao, Araguaina Sul e Neblina foram entrevistados e sangrados, independentemente de terem adoecido ou nao. Os soros tanto de adultos quanto de criancas de ambos os sexos foram usados para pesquisa de anticorpos inibidores da hemaglutinacao (IH) e IgM atraves de ensaio imunoenzimatico (MAC ELISA). Nas casas onde haviam doentes no momento do inquerito, sangue total tambem foi colhido para tentativa de isolamento de virus. O quadro clinico apresentado pelos pacientes foi caracterizado por febre, cefaleia, mialgias, artralgias e exantema do tipo maculo-papular nao pruriginoso. A infeccao foi mais frequente em mulheres (33.9%) do que nos homens (23.8%), ocorrendo em todas as faixas etarias, inclusive em criancas com menos de um ano de idade, bem como em maiores de 70 anos. Um total de 1105 mosquitos (56 femeas e 45 machos de Culex quinquefasciatus e 567 femeas e 437 machos de Aedes aegypti) foram obtidos a partir de larvas coletadas em Araguaina. As femeas de Ae. aegypti obtidas das larvas fizeram repasto sanguineo em 8 pacientes febris. O diagnostico laboratorial foi feito por isolamento de virus (cultura de celulas de Aedes albopictus, clone C6/36) e por sorologia (IH e MAC ELISA). Foram isoladas 5 amostras de DEN 2 de pacientes febris e tipadas por imunofluorescencia indireta usando anticorpos monoclonais de dengue. Nenhuma amostra viral foi isolada de mosquitos. Outrossim, comprovou-se infeccao em 111 pessoas sangradas, o que revelou um indice de positividade de 27.75% (111 em 400), sendo que 66.2% das familias estudadas apresentaram pelo menos um individuo positivo. Ocorreram ainda, 26.1% de infeccoes assintomati-cas. Por outro lado, a correlacao de positividade entre os dois testes usados (IH e MAC ELISA) foi de 94.6%. Estimamos que ocorreram aproximadamente 83.250 casos da doenca, entre 15 de marco a 31 de maio de 1991. Esta e a primeira epidemia de DEN 2 em um estado da Amazonia Brasileira, portanto em area endemica de febre amarela, e a primeira evidencia da interiorizacao do DEN 2, ate entao restrito ao Rio de Janeiro.

Primeiro registro de epidemias causadas pelo vírus Oropouche nos Estados do Maranhão e Goiás, Brasil

The authors describe the occurrence of outbreaks caused by Oropouche virus (ORO) in the states of Maranhão and Goiás, Brazil in 1988. 36 strains of the virus were obtained from the intracerebral inoculation of the blood of 120 patients into 2-3 day-old infant mice. The illness was characterized by headache, fever, pain in the muscles, joints and back, photophobia, retrobulbar pain, nausea and dizziness. 128 of 197 people examined in Porto Franco, MA, had hemagglutination-inhibiting antibodies to the agent, while 106 of them had IgM antibodies by MAC ELISA test. All age groups were infected, although the incidence was higher among who had 10 to 19 years old. There was no difference, in relation to sex infections. Recurrence of symptoms was reported in 56% of sick people. Mice inoculated with 3624 Culicoides paraensis (Ceratopogonidae) and 1970 Culex (Cux.) quinquefasciatus (Culicidae) collected in Porto Franco resulted in one single isolation of ORO virus, from the Culicoides. These are the first confirmed cases of ORO infection in Maranhão and Goiás states.The authors describe the occurrence of outbreaks caused by Oropouche virus (ORO) in the states of Maranhao and Goias, Brazil in 1988. 36 strains of the virus were obtained from the intracerebral inoculation of the blood of 120 patients into 2-3 day-old infant mice. The illness was characterized by headache, fever, pain in the muscles, joints and back, photophobia, retrobulbar pain, nausea and dizziness. 128 of 197 people examined in Porto Franco, MA, had hemagglutination-inhibiting antibodies to the agent, while 106 of them had IgM antibodies by MAC ELISA test. All age groups were infected, although the incidence was higher among who had 10 to 19 years old. There was no difference, in relation to sex infections. Recurrence of symptoms was reported in 56% of sick people. Mice inoculated with 3624 Culicoides paraensis (Ceratopogonidae) and 1970 Culex (Cux.) quinquefasciatus (Culicidae) collected in Porto Franco resulted in one single isolation of ORO virus, from the Culicoides. These are the first confirmed cases of ORO infection in Maranhao and Goias states.Os autores descrevem a ocorrencia de epidemias causadas pelo virus Oropouche (ORO) nos Estados do Maranhao (MA) e Goias (GO) em 1988. 36 amostras de virus foram obtidas a partir da inoculacao do sangue de 120 pacientes em camundongos recem nascidos. A doenca foi caracterizada por febre, cefaleia, dores musculares, articulares, fotofobia, dor retro ocular, nauseas e tontura. 128 das 197 pessoas examinadas em Porto Franco, MA, tinham anticorpos inibidores da hemaglutinacao (IH) para o agente e, em 106 foram detectados anticorpos IgM por MAC ELISA. Todos os grupos etarios foram infectados, embora a incidencia tenha sido mais elevada entre aqueles com 10 a 19 anos de idade. Quanto ao sexo, a infeccao ocorreu igualmente em ambos os sexos. Recorrencia dos sintomas foi observada em 56% dos casos positivos estudados. A inoculacao em camundongos Swiss recem nascidos de 3.624 Culicoides paraensis (Ceratopogonidae) e 1.970 Culex (Culex) quinquefasciatus (Culicidae), coletados em Porto Franco-MA, resultou em um unico isolamento do virus ORO a partir dos Culicoides. Essa e a primeira descricao de casos confirmados de infeccao pelo virus Oropouche nos Estados do Maranhao e Goias, Brasil.

Involvement of the central nervous system in dengue fever: three serologically confirmed cases from Fortaleza, Ceará, Brazil

Three cases of dengue fever involving the central nervous system (CNS) are reported. All occurred in 1994 during a dengue (DEN) epidemic caused by serotypes DEN-1 and DEN-2. The first case examined was a 17-year-old girl who complained of fever, nuchal rigidity and genital bleeding. Three blood samples were positive by anti-dengue IgM ELISA and showed hemagglutination-inhibition (HI) test titers > or = 1,280. The second case concerned a 86-year-old women with fever, muscle and joint pains, altered consciousness, syncope, nuchal rigidity and meningismus. Her blood sample showed an HI titer of 1:320 for flaviviruses, and an IgM ELISA positive for dengue. The third case was a 67-year-old women with fever, abnormal behaviour, seizures, tremor of extremities, thrombocytopenia, increased hematocrit and leukopenia. The patient suffered a typical case of dengue hemorrhagic fever with ensuing shock and a fatal outcome. A single blood sample showed HI antibodies of > or = 1,280 and an IgM ELISA positive for dengue. No virus could be isolated from any patient by inoculation of blood into C6/36 cells and suckling mice. No other agent of disease was encountered in the patient.

Estudos sorológicos para pesquisa de anticorpos de arbovírus em população humana da região do Vale do Ribeira: II - inquérito em pacientes do Hospital Regional de Pariquera-Açú, 1980

Foi realizado inquerito sorologico para pesquisa de anticorpos inibidores de hemaglutinacac de arbovirus em 516 moradores das zonas urbana e rural da regiao do Vale do Ribeira, Brasil, area extensamente coberta de florestas onde ocorreu recentemente uma epidemia de encefalite atribuida ao Flavivirus Rocio. Verificou-se que 24,2% destas pessoas tinham anticorpos IH para um ou mais arbovirus (11,2% para Alphavirus; 13,2% para Flavivirus; 4,6% para o Bunyavirus Caraparu e 0,8% para outros arbovirus). Alguns dos investigados, sem antecedente de vacinacao contra febre amarela, apresentaram anticorpos neutralizantes para o virus da encefalite equina do Leste, St. Louis e da febre amarela, os dois ultimos ainda nao isolados na regiao. A analise das caracteristicas dos individuos com sorologia positiva sugeria que a transmissao de arboviroses nao era fato recente e estava se fazendo em pelo menos 9 municipios da area, nao so no ambiente silvestre como fora do mesmo. Os individuos de sexo masculino e entre estes os que trabalham em pesca, em geral no periodo vespertino e noturno, apresentaram maior risco a infeccoes arboviricas.Foi realizado inquerito sorologico para pesquisa de anticorpos inibidores de hemaglutinacac de arbovirus em 516 moradores das zonas urbana e rural da regiao do Vale do Ribeira, Brasil, area extensamente coberta de florestas onde ocorreu recentemente uma epidemia de encefalite atribuida ao Flavivirus Rocio. Verificou-se que 24,2% destas pessoas tinham anticorpos IH para um ou mais arbovirus (11,2% para Alphavirus; 13,2% para Flavivirus; 4,6% para o Bunyavirus Caraparu e 0,8% para outros arbovirus). Alguns dos investigados, sem antecedente de vacinacao contra febre amarela, apresentaram anticorpos neutralizantes para o virus da encefalite equina do Leste, St. Louis e da febre amarela, os dois ultimos ainda nao isolados na regiao. A analise das caracteristicas dos individuos com sorologia positiva sugeria que a transmissao de arboviroses nao era fato recente e estava se fazendo em pelo menos 9 municipios da area, nao so no ambiente silvestre como fora do mesmo. Os individuos de sexo masculino e entre estes os que trabalham em pesca, em geral no periodo vespertino e noturno, apresentaram maior risco a infeccoes arboviricas.

Infecção humana adquirida em laboratório causada pelo virus SP H 114202 (Arenavirus: família Arenaviridae): aspectos clínicos e laboratoriais

Sao descritos os achados clinico-laboratoriais da infeccao acidental pelo virus SP H 114202 (Arenavirus, familia Arenaviridae), um virus novo causador de febre hemorragica humana. O paciente, tecnico de laboratorio, apresentou quadro febril por 13 dias. A doenca cursou com febre elevada ( 39oC.) diaria, cefaleia, calefrios e mialgias por 8 dias. A partir do 3o dia surgiram nauseas, vomitos alimentares e anorexia e no 10o dia, epigastralgia, diarreia e gengivorragia. Laboratorialmente, foram observadas as seguintes alteracoes: leucopenia gradativa com linfocitose a medida que a doenca evoluia, passando de 5800 para 4100, 3400 e 2500 leucocitos por mm3 de sangue com 2,5,9 e 11 dias de doenca, respectivamente. Ocorreram ainda, discretas alteracoes nas transaminases (TGO=54 e TGP=52) no 9o dia de doenca. O coagulograma e velocidade de hemossedimentacao foram normais. Conversao sorologica para o virus em apreco, foi detectada atraves dos testes de fixacao do complemento, neutralizacao e ELISA. Sangue do paciente inoculado em camundongos recem nascidos, hamsters e celulas VERO, apresentou resultado negativo para isolamento de virus. Esse virus foi isolado pela primeira vez em Sao Paulo, em 1990, a partir do sangue de um paciente que apresentou febre hemorragica com evolucao fatal. Recomenda-se extremo cuidado no manuseio desse virus por tratar-se de patogeno com riscos de transmissao por aerossois (contaminante classe III ou IV).

Estudos sorológicos para pesquisa de anticorpos de arbovírus em população humana da região do Vale do Ribeira: III - inquérito em coabitantes com casos de encefalite por Flavivirus Rocio

Foi realizado inquerito sorologico para pesquisa de anticorpos de 17 arbovirus existentes no pais, em coabitantes com doentes de encefalite por Rocio, residentes em zona urbana da regiao do Vale do Ribeira, Sao Paulo (Brasil), onde ocorreu recentemente uma extensa epidemia dessa molestia. Nao se verificou maior prevalencia de anticorpos IH para virus Rocio nessas pessoas quando comparadas com individuos que nao coabitavam com doentes de encefalite. Foram observados e discutidos alguns aspectos ja verificados em outros grupos populacionais estudados anteriormente: maior prevalencia de anticorpos IH de arbovirus em homens, particularmente pescadores; aumento dessa prevalencia com a idade e presenca de pessoa com antecedente de encefalite que apresentou, exclusivamente anticorpos neutralizantes para o Alphavirus EEL, o qual ate agora nao tem sido responsabilizado por molestia na regiao. Encontrou-se baixa proporcao de individuos com anticorpos para Rocio e Flavivirus em geral, fato este estranhavel considerando a recente epidemia.