Serological patterns and temporal trends of HTLV-1/2 infection in high-risk populations attending Public Health Units in São Paulo, Brazil.

HTLV-1/2 diagnosis in high-risk populations from São Paulo, Brazil has been problematic due a high proportion of seroindeterminate results. To confirm and extend previous findings regarding HTLV-1/2 diagnosis in this geographic area. Sera from 2312 patients were tested for HTLV-1/2 antibodies using enzyme immunoassay (EIA) and Western blot (WB) analysis. Patients were from AIDS Reference Centers (Group I; 1393 patients) and HTLV out-patient clinics (Group II; 919 patients). Results were analyzed according to patients' age, gender, and clinic type. HTLV-1 and HTLV-2 were detected in both groups. Among seropositive females, HTLV-2 was slightly more common in Group I (54.5%), while HTLV-1 prevailed in Group II (73.9%). Males from Group II had a higher percentage of HTLV-seroindeterminate results. No correlation between HTLV serological results and age was detected. Temporal analyses disclosed a high number of HTLV-seroindeterminate samples, and a large spectrum of indeterminate WB profiles. GD21 and/or rgp46-II bands were detected in 34.6% of sera from Group I, and a p24 or p19 band was detected in 35.3% of sera from Group II. High rates of HTLV-indeterminate serological patterns during temporal analyses were confirmed in high-risk populations from São Paulo, Brazil.