Seroprevalence and demographic determinants of human t-lymphotropic virus type-1 and -2 infections among first-time blood donors, u.s. 2000-2009

Objectives. We determined the seroprevalence of human T-lymphotropic virus types 1 and 2 (HTLV-1 and –2), which has not been estimated in the United States since 2001. Methods. Data on all first-time blood donors in a large network of United States blood centers was examined during the period 2000-2009. HTLV-1 and -2 antibody was measured by enzyme immunoassay (EIA) screening and repeatedly reactive samples were confirmed with immunofluorescence assay or recombinant immunoblot. Prevalence rates were calculated, and odds ratios (OR) and 95% confidence intervals (CI) for associations with demographic characteristics were assessed using multivariable logistic regression. Results. Among 2,047,740 first-time donors, 104 donors were seropositive for HTLV-I infection (prevalence 5.1 (95% CI: 4.1 - 6.1) per 100,000) and 300 donors were seropositive for HTLV-2 infection (prevalence 14.7 (95% CI 13.0 - 16.3) per 100,000). Prevalence was lower than reported in the 1990's but stable from 2000 to 2009. HTLV-1 infection was associated with female sex (OR = 1.56, 95% CI 1.05-2.32), older age, and Black and Asian race/ethnicity, whereas HTLV-2 infection was associated with female sex (OR = 2.13, 95% CI 1.67-2.73), older age, Black, Hispanic and Other race/ethnicity , Western (OR=4.12, 95% CI 2.16-7.82) and Southwestern (OR=2.47, 95% CI 1.28-4.78; both vs. Northern) regions, and lower educational level. Conclusions. HTLV-1 and -2 prevalence has stabilized in United States blood donors since the turn of the century. Higher prevalence of HTLV-2 in the West and Southwest may be attributed to localization of injection drug use or endemic Amerindians.