Isolation of dengue 2 virus from a patient with central nervous system involvement (transverse myelitis)

A dengue fever case is described in a 58-year-old male patient with febrile illness and thrombocytopenia complicated by neurological involvement characterized by transverse myelitis followed by weakness of both legs and flaccid paralysis. Muscle strength was much diminished and bilateral areflexia was observed. Dengue 2 (DEN-2) virus was isolated and the patient sero-converted by hemagglutination-inhibition and IgM-ELISA tests. The RT-PCR test was positive to DEN-2 in acute phase serum and culture supernatant, but negative in the cerebrospinal fluid. After three weeks of hospitalization the patient was discharged. No other infectious agent was detected in the blood and cerebrospinal fluid samples. The patient had full recovery from paralysis six months after the onset of DEN-2 infection.

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

Um total de 187 diferentes espécies de arbovírus, além de outros vírus de vertebrados, foram identificados pelo Instituto Evandro Chagas (IEC) no período de 1954 a 1998, entre as mais de 10.000 cepas de vírus isoladas de seres humanos, insetos hematófagos e vertebrados-sentinela e silvestres. Apesar dos estudos intensivos realizados na Amazônia brasileira, sobretudo no Estado do Pará, pouco se sabe a respeito da maioria desses vírus, com exceçäo de dados a respeito de data, hora, fonte e método de isolamento, assim como a capacidade de infectar animais laboratoriais. Fazem uma revisäo dos dados ecológicose epidemiológicos e procuram associar o impacto, sobre os diversos vírus, das mudanças populacionais dos vetores e hospedeiros induzidas por profundas alteraçöes no meio ambiente. O desmatamento, o uso do subsolo, a construçäo de represas e de rodovias, a colonizaçäo humana e a urbanizaçäo foram as principais modificaçöes ambientais introduzidas pelo homem e associadas à emergência ou reermegência de importantes arbovírus, inclusive alguns com atividade patogênica em seres humanos.

Inquérito soro-epidemiológico na Ilha de Säo Luis durante epidemia de dengue no Maranhäo / Seroepidemiologic survey in Säo Luis Island, State of Maranhäo, Brazil, during a dengue fever epidemies

Nos anos de 1995 e 1996, ocorreu em Säo Luis uma epidemia de dengue (DEN), causada pelo sorotipo DEN1. Objetivando avaliar o impacto da mesma na populaçäo da grande Säo Luis (municípios de Paço do Lumiar - PL, Säo José de Ribamar - SJR e Säo Luis SL), realizamos um inquérito soro epidemiológico aleatório, onde aplicamos um questionário. Os soros foram testados por inibiçäo da hemaglutinaçäo (IH) e os resultados negativo e positivo (resposta primária - RP e resposta secundária RS), foram analisados utilizando os "software's" Lotus 123, Epi-info 6.0. Excel 5.0 e STATA. Coletaram-se 1277 amostras, (101 de PL, 100 de SJR e 1016 de SL). A positividade foi: 55,4 por cento em PL, 28 por cento em SJR e 41,4 por cento em SL. Destes, 505(4.1,2 por cento) amostras foram positivas sendo 96 RP (7,9 por cento) e 405 RS (33,3 por cento). Da amostra obtida, 508 soros (227 positivos) foram do sexo masculino e 709 (278 positivos) do feminino, näo havendo diferença estatística significativa. Houve significância (p < 0,003) na estratificaçäo de acordo com a renda, sendo mais freqüente nas populaçöes com melhor nível sócio econômico. Estimou-se em 401.933 infecçöes causadas pelo vírus dengue. Os pacientes referiram febre, cefaléia, calafrios, tonturas, astenia, dor retro ocular, mialgia, artralgia, náuseas, anorexia, prurido e exantema. Há uma grande populaçäo sensibilizada pelo DEN-1, suscetível a outro sorotipos o que aumenta o risco de dengue hemorrágico

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

Neste trabalho säo descritos tres casos de dengue com manifestaçöes neurológicas incomuns durante a epidemia de dengue em Fortaleza, Estado do Ceará, em 1994. Todos os pacientes eram do sexo feminino. A paciente do primeiro caso tinha 17 anos e apresentou além da sindrome febril, sinais de comprometimento meningeo com rigidez de nuca, e sangramento genital. No segundo caso a paciente de 86 anos apresentou quadro febril, intensa dor muscular e articular, alteraçöes da consciencia, desmaio, rigidez de nuca e meningismo. A terceira, de 67 anos, teve um quadro inicial de sindrome febril, seguido de comportamento anormal, tremores de extremidades, trombocitopenia, hematocrito aumentado, leucopenia, hipotensäo arterial e choque, evoluindo para obito...

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

Epidemia de dengue em Fortaleza, Ceará: inquérito soro-epidemiológico aleatório / Dengue epidemic in a Northeastern Brazil: random epidemiological serum survey

Seguindo-se à epidemia de dengue (DEN), em 1994, em Fortaleza, Ceará, causada pelo sorotipo 2 (DEN-2), realizou-se inquérito soro-epidemiológico aleatório para avaliar e dimensionar o impacto da mesma e a prevalência do dengue por distrito sanitário. Foi aplicado questionário contendo informaçöes gerais, condiçöes socio-econômicas, informaçöes sobre o quadro clínico e tempo de doença. A amostra foi calculada para estimar uma prevalência de 20 por cento, com erro relativo de 10 por cento, e intervalo de confiança de 95 por cento (erro a de 5 por cento). O sorteio e as análises foram realizadas por meio de computador usando programas apropriados. Foram colhidas 1.341 amostras de soro de 9 distritos sanitários, testadas por inibiçäo da hemaglutinaçäo, sendo classificadas como negativas e positivas (respostas primária - RP e secundária - RS). Foram reativas 588 (44 por cento) amostras, sendo 93 (7 por cento) RP e 495 (37 por cento) RS. A prevalência global em Fortaleza variou de 21 por cento a 71 por cento. Houve 41 por cento (243/588) de infecçöes assintomáticas (IA) e 59 por cento (346/588) sintomáticas (IS). Näo houve diferença da prevalência quanto ao sexo, faixa etária e escolaridade, ao contrário da condiçäo socioeconômica que apresentou diferenças estatisticamente significantes (p<0,001). Ocorreram mais IA (p<0,001) e IS (p<0,0001) em casos de RS que RP, com significância estatística em ambos os sexos. Os sintomas mais prevalentes nos casos confirmados foram febre, cefaléia, mialgias, exantema, mal estar geral, tontura e artralgias, sendo que prirido, dor ocular, exantema e gengivorragia foram estatisticamente significantes (p<0,005). Tontura e artralgias foram mais associados com RS que com RP, havendo diferenças estatísticas (p<0,05)

Epidemia de febre do Oropouche em Serra Pelada, município de Curionópolis, Pará, 1994 / Fever epidemic of Oropouche virus in Serra Pelada, municipality of Curionópolis, Pará State, 1994

In the final of November 1994, an outbreak of a febrile disease was observed in the Serra Pelada gold mine (5 degrees 35'S: 49 degrees 30'W) in the Southeast region of Pará State. Twenty samples were collected and sent to the laboratory of Arbovirus of Instituto Evandro Chagas. The tests showed that the disease was caused by Oropouche virus (Bunyaviridae, Bunyavirus, Simbu serological group). Between 8-22 December 296 serum samples were taken (54 from febrile patients, 16 paired samples and 242 from contacts and convalescent patients) of the 73 familiar groups. From febrile patients, ten Oropouche virus strains were obtained. From paired serum, six seroconversions were obtained and 242 other Oropouche infections were diagnosed by HI and MAC ELISA. The clinical-picture of febrile disease accompanied by severe bedache, chills, myalgia, photophobia retrobulbar pain and malaise was observed. Involvement of central nervous system was not observed. Based on the serological data, we estimated that in the outbreak of Serra Pelada around 5,000 cases occurred corresponding to a prevalence of 83 per cent.

Modifications of arbovirus transmission in relation to construction of dams in Brazilian Amazonia

The Amazonian region of Brazil seems to be the world's richest reservoir of arboviruses. To date, 183 different types of arboviruses have been detected in the Amazonian region, accounting for more than one third of the 535 arboviruses reported in the world. Of these, 136 (74.3 per cent) are endemic. The main objective of this paper was to evaluate what the effects of the construction and flooding of dams would be on the transmission and epidemiology of sylvatic arboviruses, in order to define the potential health hazards to which the human population would be subjected. Five areas were surveyed but only one could be thoroughly studied. Comparisons were made between surveys: i) inside the dam region, before, during and after the flooding period; ii) outside the dam region, in an area with a similar climate, landscape and vegetation, during the total time of the studies. The two chosen areas, namely Altamira and Tucuruí, were studied since 1974, and since September, 1982, respectively. The former, and the latter before the outset of flooding (September 6, 1984) were considered as a control or reference for comparisons with data obtained in Tucuruí during flooding and thereafter. The surveys consisted of sampling as many wild vertebrates and haematophagous Diptera as possible. Human sera were collected from febrile cases and random serological surveys. Very few variations seem to have occurred among the three phases of the study, with a maximum of positive serologies during the flooding period, but the differences were not statistically significant. Similarly, in the reference region, the prevalence of antibodies against the four more important arbovirus groups did not vary significantly. The arboviruses were classified under two categories: i) those which showed enhanced transmission and ii) those which showed no apparent modifications in their transmission patterns (referring to the control area). Three new and three already known types in the Anopheles A group of Bunyavirus were favoured by the great proliferation of Anopheles nuneztovari and An. triannulatus which accompanied the flooding of the dam. An epizootic of the Gamboa virus (Bunyavirus, Gamboa serogroup), newly reported in Brazil, was observed one year after the outset of flooding, when the mosquito Aedeomyia squamipennis showed very large populations. Guaroa (Bunyavirus, California group), an endemic arbovirus, showed an epizootic probably as a consequence of the proliferation of anopheline mosquitoes. A temporary proliferation of Culex spp. mosquitoes and the presence of a rich avifauna in the dam area during flooding are probable causes of the enhanced circulation of Turlock (Bunyavirus, Turlock group) and Kwatta-like (Rhabdoviridae, Kwatta group) viruses...

New entomological and virological data on the vectors of sylvatic fever in Brazil

The present report focuses on recent ecoepidemiological data on yellow fever, obtained recently in two very distinct ecoepidemiological contexts: the Barcarena (PA) area, situated in the dense Amazonian rain forest, and the Campo Grande (MS) region, situated in the cerrado with gallery forest in central Brazil. In the first region, one strain was isolated from a pool of 6 Haemagogus janthinomys. In the other region, 2,480 anthropophilous mosquitoes were collected, of which near 40 per cent were potential YF vectors. These species, classified by decreasing relative abundance, were: Aedes scapularis, Sabethes chloropterus, Hg.janthinomys, Hg. leucocelaenus, Hg. spegazinii, and Sa. soperi. Four strains of YF virus were isolated from Hg. janthinomys, one from Sa. cheoropterus (first report for South America) and one from Sa. soperi (first report). The minimal infection rates varied among the three localities of collection but were all high, compared with previous data. The mean daily survival rate was O.9635 for the populations of Hg. janthinomys, allowing extrapolation of the value of the infection rate when people were infected most recently. It was deduced that the epizootics were intense and more or less concomitant in the three areas. The main problem that remained to be solved concerns the mode(s) of reintroduction or survival of YF virus in each of the two regions under study.

A comparative study of yellow fever in Africa and South America

In order to look for an ecoepidemiological model of sylvatic yellow fever (YF) transmission in South America, differences from and similarities to available African YF data are considered. Strains from both areas, representing various topotypes, are distinct serologically, genetically and biochemically. In Africa, all vector mosquitoes are Aedes species, some related to the forest cycle and others responsible for the transmission in dryer areas. In South America, and particularly in Brazil, the main vector is Haemagogus janthinomys. Hg. albomaculatus has been incriminated in human peridomestic transmission in Central Amazonia. In the two continents, monkeys are the only regular vertebrate hosts of YF but the indigenous neotropical monkeys, show higher mortality rates. The South American and African vectors are diurnal and crespuscular/nocturnal in habit, respectively. The urban vector (Ae. aegypti) has the same habits in both continents, but its competence in transmitting the virus is very variable, and no urban epidemic has been notified in South America since the 4Os. A general ecoepidemiological model was elaborated to explain the maintenance and circulation of YF virus in West and Central Africa, which are related to the phytoclimatical regions. Because no such hypothesis has yet been presented in the case of YF in South America, we tested this with the available data from Brazil. All occurrences (of which 386 were lab-confirmed) were distributed in five phytogeographical zones: dense rain forest (l89), open rain forest (30), savannah with gallery forest (l47), ecotones (lO) and decidual seasonal forest (7). For each of these zones mean intervals between years with occurrences of YF were estimated. They were all found to be lower than 3 years, and lower than 5 years when standard deviation was added. Despite the close values obtained for the means, the distribution of the years as a function of number of occurrences of YF showed two groups: a) gallery forest and dense forest and b) open forest and ecotones. However, more data are necessary to enable the study of such variations which are thought to be related to ecological differences in YF transmission.

Arboviruses in Serra Norte, Carajás region, Pará, Brazil

mhis report outlines studies carried out from 1982 to 1987 in Serra Norte, Carajás region, Pará State, to ascertain the existence of known or new arbovirus types in the area, especially those of medical interest, and to gather information about their natural patterns of activity. These studies have included both serological tests and attempts to isolate viruses from haematophagous insects, wild animals and man. A total of 184,884 haematophagous insects were collected and blood and tissue samples were obtained from 1,726 wild vertebrates caught in the area. Attempts to isolate viruses in suckling mice yielded 21 strains, including 15 different serological types, of which 7 have been shown to constitute new types, so far found only in the Brazilian Amazonian region, and two of them have already been confirmed to be new types to the world. Serological studies performed on 2,680 sera (1,380 humans and 1,300 wild animals) against selected arboviruses pointed out the circulation of several of these agents in the investigated area. The Carajás region therefore, maintains established ecosystems which are rich in arbovirus fauna, and exploration of these natural niches must be done carefully and rationally to avoid breaking out the current foci of infestation maintained in the forest. Further studies are necessary to obtain a better understanding of these agents in this region and of the threats that they may pose to the health of humans and livestock.