Walsh & Hoyt: Human T-Cell Leukemia Virus Type I

HTLV-1 is endemic in Japan as well as in other parts of the world including the Caribbean, sub-Saharan Africa, and Australia. It is estimated that there are 1020 million carriers of this virus in the world. HTLV was likely present in humans before the movements of primitive populations around the world. The highest prevalence of HTLV-I infection is in southwestern Japan, where about 20% of the adult population is seropositive, and in the Caribbean basin (West Indies, northern South America, and southeastern United States), where 25% of individuals are seropositive. Seroprevalence increases with age, and rates usually are higher in women than in men. In the United States, the HTLV seroprevalence rate among volunteer blood donors is approximately 0.016%, with about half of these due to HTLVI.