Significance of Postnatal Mother‐to‐Child Transmission of Human T‐lymphotropic Virus Type‐I on the Development of Adult T‐cell Leukemia/Lymphoma

Abstract

In order to shed light on the mode of HTLV‐I infection by mother‐to‐child transmission, we examined sera of school children in a highly endemic town on two separate occasions at a 6‐year interval. The carrier rates in ages 15–17, 8.7 and 2.1%, were significantly higher than that in ages 6–8, 1.7 and 0.4%, in studies. The latter survey showed a significantly lower carrier rate in each age group. Moreover, the carrier rates of those students born in 1965–1967 and 1968–1970 were stable in the interval. The data suggested that carrier rates of children at certian ages are reflected by the date of birth rather than by age.A prospective survey of children born of carrier mothers found the overall carrier rate to be approximately 25%, which did not increase with their age. There was no sexual difference in the carrier rate of children: 5/25 in male and 9/34 in females (χ² = 0.3). Carrier mothers could be separated into two groups: HTLV‐I antigen‐positive mothers and negative mothers. Nine out of 19 antigen‐positive mothers (47%) and 2 of 19 antigen‐negative mothers (11 %) had carrier children (χ² = 6.3). Twelve of 30 children born of antigen‐positive carrier mothers (40%) were carriers, in contrast to 2 of 24 children (8%) of antigen‐negative mothers (χ² = 7.8). Furthermore, 12 of 14 carrier children (86%) were of antigen‐positive mothers. This suggests that postnatal but early transmission of HTLV‐I plays a significant role in the maintenance of HTLV‐I endemy and the development of adult T‐cell leukemia/lymphoma.