RESUMEN
Serological studies on 926 blood samples from 703 Brazilian Kayapo (Cayapo) Indians showed, by conventional definition of HTLV seropositivity, a 28% prevalence of human T lymphotropic virus (HTLV) infection, the highest yet reported. Immunoblot (WB) and SYNTH-EIA patterns indicate that the predominant infecting agent is type II. Of children under 15 years old, 12% were positive, and of persons over 60, more than 60%. Perinatal and heterosexual modes of transmission offer an adequate explanation of this incidence. Infection in infancy may include infection via breast milk from women other than the mother. Evidence of new infection in adults is apparent at an earlier age in women than in men. This pattern of antibody prevalence was not determined by cohort effects, as demonstrated by tests of serial specimens. Enzyme immunosorbent assay (EIA) absorbencies were not stable in the paired specimens: five serum pairs reverted and mean absorbencies declined over some age ranges. Many specimens with relatively high, but less than positive, EIA results were positive by immunoblot (WB). This suggests that the standard EIA end point does not identify all infected persons. If the WB alone indicates positivity, 47% of the whole population, and more than 80% of the older age groups, are infected with HTLV-II.
Asunto(s)
Anticuerpos Anti-HTLV-II/sangre , Infecciones por HTLV-II/epidemiología , Infecciones por HTLV-II/transmisión , Indígenas Sudamericanos , Adolescente , Adulto , Factores de Edad , Brasil/epidemiología , Niño , Preescolar , Demografía , Ensayo de Inmunoadsorción Enzimática , Familia , Femenino , Infecciones por HTLV-II/sangre , Humanos , Lactante , Masculino , Persona de Mediana Edad , Prevalencia , Factores SexualesRESUMEN
Detection of human T lymphotropic virus type I (HTLV-I) antibody was assessed on 368 sera from subjects with different clinical features and from different parts of the world. Enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay for purified p24 antibodies (p24-RIA) used as screening tests agreed in 88.7% of the sera. The results from 247 selected sera were compared with western blot (WB). WB was reactive in sera five to 25 times more dilute than the last positive ELISA or p24-RIA, but different WB batches varied in sensitivity. ELISA was more sensitive than p24-RIA, and p24-RIA was more specific than ELISA. Indeterminate WB interpretations were common (25.5%). Most seropositive intravenous drug abusers had unusually strong p24 bands by WB. Among healthy individuals, positive WB reactivity increased with age, whereas indeterminate reactivity declined (P = .034). Thus, more-sensitive and -specific HTLV-I antibody tests are needed.