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

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

Occurrence of Pacora virus (PAC: Bunyaviridae: Bunyavirus - like) in Brazilian Amazonia: new findings

The Pacora virus (PAC: Bunyaviridae: Bunyavirus - like), was known only through some isolates obtained from mosquitoes (culex dunni) in Panama, and two isolates obtained in the Brasilian Amazon region from the sylvatic birds Phlegopsis nigromaculata and Automolus ochrolaemus. In order to add to the knowledge of the arboviruses' cycles, mosquitoes were colected in the Zoobotanical Park of Macapá (Amapá State), from August, 18th to September, 11th, in areas of rain forest and savannah. The collections were done at both ground and canopy levels in the savannah, with human bait and light traps. 5642 mosquitoes have been collected, of which 5580 (or 184 pools) have been inoculated intracerebrally in newborn mice. Two strains of PAC virus have been isolated from unidentified Culex mosquitoes. This result is the first report of PAC virus in Amapá State. The virus has also been isolated for the first time from mosquitoes in Brazil. Thus, the presence of the complete cycle of sylvatic transmission of this agent is confirmed in Brazilian Amazonia. The ecological data available for the host show that the virus circulates at the lower level in the rain forest (0-5 m) with mostly nocturnal mosquitoes as vectors.

Infeccao humana adquirida em laboratorio causada pelo virus SPH 114202 (Arenavirus: familia Arenaviridae): aspectos clinicos e laboratoriais / Laboratory acquired infection by the virus SP H 114202 (Arenavirus : Arenaviridae) : clinical and laboratory findings

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 3§ dia surgiram nauseas, vomitos alimentares e anorexia e no 10§ dia, epigastralgia, diarreia e gengivorragia....

First documented outbreak of dengue in the Perúvian Amazon Region

This article describes a classical dengue outbreak caused by dengue serotypes 1 and 4 that occurred from March to July 1990 in the city of Iquitos and surrounding áreas of Loreto Department in the Perúvian Amazon. Epidemiologic data indicate that more than 150,000 persons may have been affected in Iquitos alone. Another dengue outbreak occurred in Tarapoto, a city in the neighboring department of San Martin. Laboratory data indicate that the same dengue serotypes were involved in both outbreaks. No cases of dengue hemorrhagic fever/shock syndrome appear to have occurred. Prior to this outbreak, no indegenous dengue cases had been documented in Perú

Epidemiologia das encefalites por arbovirus na Amazonia brasileira / Epidemiology of encephalitis caused by arbovirus in Brazilian Amazonia

Os autores reveem os aspectos ecoepidemiologicos apresentados pelos virus da encefalite de St. Louis (SLE), encefalites equinas Leste (EEE), Oeste (WEE) e Venezuelana [subtipos III, Mucambo (MUC) e IV, Pixuna (PIX)], decorrentes dos estudos realizados em diversas areas da Regiao Amazonica brasileira, especialmente ao longo das rodovias e projetos de desenvolvimento. Esses virus sao amplamente distribuidos na Amazonia e pelo menos quatro deles, EEE, WEE, MUC e SLE ja demonstraram ser patogenos do homem. O diagnostico da doenca humana foi feito por sorologia, sendo que de MUC e SLE obteve-se tambem isolamento viral. O virus PIX, parece ser o menos prevalente e foi isolado em poucas oportunidades. Virtualmente se desconhecem os vetores do PIX e WEE. As aves silvestres constituem os hospedeiros principais de todos esses virus, exceto do MUC, para o qual constituem os roedores. O quadro clinico apresentado pelos pacientes infectados na Amazonia e discutido, comparando-o ao apresentado em outras areas, especialmente nos EUA, onde periodicamente SLE, EEE e WEE causam surtos de doenca humana. Nenhuma epidemia foi ate o presente detectada, embora em 1960 uma epizootia em equinos causada pelo EEE tenha sido registrada em Braganca, Para, onde um rebanho de 500 animais ocorreu uma letalidade de 5 por cento.