ABSTRACT
The epidemiology of hepatitis A virus (HAV) infection is shifting from high to intermediate endemicity in Brazil, resulting in increased numbers of susceptible individuals and a greater potential for the emergence of outbreaks. Universal vaccination against HAV has been recommended for children, but updated sero-epidemiological data are necessary to analyze the level of natural immunity and to identify candidates for preventive measures. In addition, more molecular studies are necessary to characterize the genotypes involved in HAV infections and outbreaks. Sera from 299 school children (5-15 years old) and 25 school staff members, collected during an outbreak of HAV at a rural public school in June 2000, were tested for IgM and total anti-HAV antibodies (ELISA). Viral RNA was amplified by RT-PCR from anti-HAV IgM-positive sera and from 19 fecal samples. Direct nucleotide sequencing of the VP1/2A region was carried out on 18 PCR-positive samples. Acute HAV infection was detected by anti-HAV IgM in 93/299 children and in 3/25 adult staff members. The prevalence of total anti-HAV antibodies in IgM-negative children under 5 years of age was only 10.5 percent. HAV-RNA was detected in 46 percent IgM-positive serum samples and in 16 percent stool samples. Sequence analysis showed that half the isolates belonged to subgenotype IA and the other half to IB. On the basis of these data, mass vaccination against HAV is recommended without prevaccination screening, especially for children before they enter school, since nearly 90 percent of the children under 5 years were susceptible. Molecular characterization indicated the endemic circulation of specific HAV strains belonging to subgenotypes IA and IB.
Subject(s)
Humans , Child, Preschool , Child , Adolescent , Adult , Middle Aged , Genetic Variation , Hepatitis A Virus, Human/genetics , Hepatitis A/virology , Brazil/epidemiology , Disease Outbreaks , Hepatitis A Antibodies/blood , Hepatitis A/epidemiology , Immunoglobulin G/blood , Phylogeny , RNA, Viral/genetics , Rural Population , Seroepidemiologic StudiesABSTRACT
A heminested-PCR (hn-PCR) using primers to the nucleoprotein-coding gene in a nested set was evaluated in the detection of Brazilian strains of rabies virus (RV). A representative number of RV nucleoprotein sequences belonging to genotype 1 were aligned. Based on such alignment, primers were directed to highly conserved regions. All 42 clinical samples positive by both fluorescent antibody and mouse inoculation tests were also positive by the hn-PCR. Brain tissue that had been left to decompose, obtained from an experimentally inoculated mouse was tested by hn-PCR and yielded positive results. In conclusion, primers designed here were capable of amplifying Brazilian RV isolates obtained from a rural epidemiological cycle
Subject(s)
Animals , Mice , Polymerase Chain Reaction , Rabies , Rabies virus , Animal Diseases , Brain , Brazil , Chiroptera , DNA Primers , Fluorescent Antibody Technique , Genotype , Mammals , Nucleoproteins , Rabies , Rabies virusABSTRACT
O segmento anterior do globo ocular, mais particularmente a conjuntiva, constitui um modelo experimental de "órgäo de choque" em relaçäo a agentes agressores ambienciais. Face à hipótese de existir uma reaçäo imunológica de defesa, os autores estudam em particular a vertente humoral desta. Neste sentido, analisam um grupo de doentes com exposiçäo aerogénea, alguns deles com manifestaçöes patológicas, classificadas por outros como Granulomatoses de Causa Inalatória. Säo doseados, na secreçäo lacrimal, as imunoglobulinas dos tipos A, G, E e M. Comentam-se os resultados