Francisco de Paula Pinheiro

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.

Enterovirus 71 infection and acute neurological disease among children in Brazil (1988–1990)

Surveillance for Enterovirus 71 (EV-71) infection in children up to 15 years of age was carried out in Brazil, from 1988 to 1990. Patients with acute neurological diseases (AND) such as flaccid paralysis, Bells palsy, acute cerebellar ataxia and Guillain-Barré syndrome were included in the study. EV-71 infection was detected in 24 of 426 children (5.6%) with AND. EV-71 infection was confirmed only by virus isolation in 13 children, by virus isolation and seroconversion in 4, and by seroconversion alone in 7. EV-71 was also isolated from 15 of the 427 household contacts (3.5%) of 165 AND patients. There was some evidence of high infectivity of EV-71: household clusters were detected in the case of 7 of 24 children (29.1%) infected with EV-71 and manifesting AND; EV-71 was isolated from 11/40 household contacts (27.5%) of the infected patients but from only 4/387 household contacts (1.0%) of children in whom it was not possible to demonstrate EV-71 infection. Seven of the 24 children infected with EV-71 exhibited residual motor deficiency when examined 6 months after the disease onset. The relevance of these results for the Plan for Global Eradication of Wild Poliovirus is discussed, as well as the need to increase knowledge about the behaviour of this virus and its possible association with AND.

Amapari, a New Virus of the Tacaribe Group from Rodents and Mites of Amapa Territory, Brazil.

Summary Amaparí virus is a new member of the Tacaribe virus group which has been isolated on 5 occasions at Serra do Navio, Amapá Territory, Brazil, during 1964 and 1965. One strain was recovered from organs of Neacomys, 3 from organs of Oryzomys and 1 from mites combed from Oryzomys. The new virus is closely related in complement-fixation (CF) testing to the other 3 members of the group—Tacaribe, Junín and Machupo—but differs from them in neutralization testing. Limited studies revealed no neutralizing antibody in sera of human residents of Serra do Navio. Oryzomys captured in the area had CF but not neutralizing antibody.

Characterization of the Changuinola Serogroup Viruses (Reoviridae: Orbivirus)

The antigenic, biological, and chemical properties of 24 selected Changuinola serogroup viruses were examined. The viruses tested were chloroform-resistant, and they were lethal to newborn hamsters after intracerebral inoculation. The prototype Changuinola virus strain (BT-436) replicated in mosquito and sandfly cell cultures. In complement-fixation tests, the viruses were broadly cross-reacting and indistinguishable; but by neutralization test at least 12 distinct serotypes were identified, and by PAGE of double-stranded RNA 22 distinct profiles were found. These data suggest that the Changuinola serogroup may be comprised of a large number of genetically different viruses. A brief review of the natural history of Changuinola serogroup viruses is also given.

A study on dissociation of Coxsackie B4 virus-antibody complex ☆

Abstract Dissociation of neutralizing antibody from Coxsackie B4 virus was achieved by acid treatment; pH 2.5 was found to be optimal for the reaction. Reactivated virus could be reneutralized by the dissociated antibody, but at a slower rate than the initial neutralization. Simple dilution was an effective method for recovering infectious virus from virus-antibody mixtures only if these mixtures were first adjusted to an acid pH. In the presence of excess antibody, recovery of infectious virus increased five- to sevenfold if the acidified virus-serum mixture was diluted in hypertonic rather than isotonic saline.

Arbovirus antibodies in children of rural Guanabara, Brazil.

School children living in Guanabara State, Brazil, have been tested for evidence of infection with 16 arboviruses. 3 percent were positive, and in every instance the positive reaction was attributable to St. Louis encephalitis (SLE) virus. Evidence of familial aggregation was observed.