Vietnamese female sex workers in rural cross-border areas of Guangxi, China: migration and HIV/STI risk behaviors

China's HIV/AIDS epidemic continues to grow in rural and less developed areas. This consecutive cross-sectional study examines demographic and behavioral factors associated with HIV/STI infection, Hepatitis C (HCV) and other sexually transmitted infections (STIs) among Vietnamese female sex workers (FSW), a vulnerable population who cross into Guangxi, China. This study is a secondary data analysis of 303 Vietnamese and 4,348 Chinese FSWs recruited over seven years from two Chinese counties that border Vietnam. Logistic regression models compared demographics, HIV/STI status, HIV/AIDS-related knowledge, attitudes, and risk behaviors between Vietnamese FSWs and Chinese FSWs. Compared with Chinese FSWs, Vietnamese FSWs were younger, had attained lower education levels, were highly mobile, more likely to report using drugs, and were more vulnerable to HIV/STIs. Younger age, less educational attainment, shorter time in their current working location, no voluntary HIV testing in the last year, greater drug use, and not using condoms for all commercial sex in the last month were associated with higher HIV/STIs. In conclusion, several factors were associated with HIV/STI risk in Vietnamese cross-border FSWs. There is a pressing need to improve support systems for Vietnamese cross-border FSW and health system cooperation across the Chinese/Vietnamese border.