Horizontal transmission of hepatitis B virus infection to United States-born children of Hmong refugees.

There is evidence that hepatitis B virus (HBV) transmission continues among Southeast Asian refugees after resettlement. To determine the prevalence of HBV infection (hepatitis B surface antigen [HBsAg] positive or core antibody positive) and modes of transmission in Hmong refugee households in Wisconsin, results of serologic tests were reviewed for 429 US-born children not previously vaccinated with hepatitis B vaccine and 754 of their Asian-born household members. The prevalence of HBV infection was 14% (62/429) among all US-born children, 30% (21/69) among children whose mothers were HBsAg-positive, and 11% (41/360) among children whose mothers were HBsAg-negative. Among children whose mothers were HBsAg-negative, the prevalence of HBV infection increased with increasing age (chi 2 test for trend = 5.6, P = .02) and was related to the household presence of HBsAg-positive sibling(s) (relative risk = 4.0; 95% confidence interval = 1.5, 9.3; P less than .001). Of the 62 infected children, 13 (21%) lived in households with no HBsAg-positive household members. US-born children of Hmong refugees apparently acquire HBV infection through both horizontal and perinatal transmission. These findings emphasize the importance of routinely integrating hepatitis B vaccine doses into the childhood vaccination schedule for all infants whose parents are from areas where HBV infection is highly endemic. In addition, the findings support the need for pediatricians to consider vaccinating older children (up to age 7 years) whose parents are from HBV-endemic areas.