Intrafamilial transmission and risk assessment of HTLV-I among blood donors in southern Taiwan.

The human T-lymphotropic virus type I (HTLV-I) is one of the important etiological agents of adult T-cell leukemia/lymphoma and of HTLV-I associated myelopathy or tropical spastic paraparesis. There is still a lack of data concerning HTLV-I transmission by seropositive carriers in Taiwan. We investigated the patterns of HTLV-I intrafamilial transmission in HTLV-I seropositive blood donors and assessed the risk factors of HTLV-I transmission in relatives of HTLV-I carriers in Taiwan. A total of twenty HTLV-I seropositive donors and their 103 relatives were enrolled. Among those 103 relatives, 40 (38.8%) were seropositive for HTLV-I. Their ages ranged from one to 70 years old with a mean age of 31.0 +/- 1.65 year-old. Three of the ten wives of male carriers were HTLV-I seropositive. However, none of the six husbands of female carriers were HTLV-I seropositive. Mother-to-child vertical transmission was found in nine of 48 (18.8%) tested. Significant risk factors of HTLV-I transmission among relatives of HTLV-I carriers were hospital admission, previous transfusion, breast feeding, anti-HCV seropositivity and female relatives of age >/= 30 with odds ratio (OR) of 9.73, 8.64, 4.36, 8.86 and 4.91, respectively (all p < 0.05). Nonsignificant risk factors of HTLV-I transmission were sharing needles, operation history, HBsAg seropositivity and male relatives of age >/= 30. Our findings suggest that mother-to-child and husband-to-wife transmissions are the important forms of intrafamilial transmission of HTLV-I in Taiwan. Screening for HTLV-I in family members of HTLV-I seropositive blood donors may be warranted.