[Human T-cell lymphotropic virus in family members of seropositive blood donors: silent dissemination].

Objective: To investigate human T-cell lymphotropic virus transmission among family members of asymptomatic carriers identified through blood donor screening tests; and to determine the most likely direction of transmission in sexual partners having the same (concordant) serological diagnosis.

Methods: Between March 1997 and June 2003 the relatives and steady sexual partners of seropositive, asymptomatic blood donors were investigated for the presence of human T-cell lymphotropic virus type I and II. Diagnosis was based on enzyme-linked immunoassay and Western blot. To determine the direction of transmission, demographic and behavioral data were obtained through questionnaires. All participants lived in the metropolitan region of Belo Horizonte capital of the state of Minas Gerais, Brazil.

Results: The overall prevalence of infection with human T-cell lymphotropic virus type was 25.9% among 352 relatives of 343 seropositive patients. The prevalence rates in mothers, sexual partners, and children of seropositive donors were 36.6% (15/41), 35.9% (42/117), and 17.5% (34/194), respectively. The demographic and behavioral data obtained suggest greater efficiency of male-to-female transmission.

Conclusion: The observed prevalence rates suggest there is familial aggregation of human T-cell lymphotropic virus infection. The main transmission mode was horizontal (sexual). It is important to identify the presence of the virus in family members of infected individuals, even if they are asymptomatic. Doing so may lead to a better understanding of how the virus spreads and more efficient measure for preventing disease transmission.