HIV monitoring in Vietnam: system, methodology, and results of sentinel surveillance.

OBJECTIVE: To measure the prevalence of and trends in HIV infections in populations defined by sentinel surveillance in Vietnam.
METHODS: Surveillance was conducted in eight provinces in 1994, expanded to 12 in 1995 and to 20 in 1996. Sentinel populations were sexually transmitted disease (STD) patients, female sex workers (FSW), injecting drug users (IDU), tuberculosis (TB) patients, pregnant women, and military conscripts. Samples were collected twice yearly for high-risk populations and once yearly for low-risk populations.
RESULTS: The overall HIV epidemic in Vietnam comprises several different smaller epidemics. It is primarily associated with injecting drug use, but its extent varies widely throughout the country. In 1998, HIV prevalence rates ranged from 0 to 85% (median, 13.1%), with an aggregate prevalence rate (APR; i.e., the sum of HIV-positive study subjects divided by the sum of all study subjects tested in sentinel provinces) of 17% among IDUs; this ranged from 0 to 14.7% (median, 0.8%), with the APR of 2.4% among FSWs; and from 0 to 6% (median, 0%), with the APR of 0.9% among STD patients. The APRs among antenatal women and army conscripts were less than 0.15%. APRs increased significantly from 1994 to 1998 among STD patients (p < .001), FSWs (p < .001), TB patients (p < .001), and pregnant women (p < .05) in original sentinel provinces. HIV prevalence also increased significantly among younger age groups of IDUs and FSWs.
CONCLUSION: Vietnam's HIV epidemic is increasing predominantly and most rapidly among IDUs. However, prevalence rates among FSWs and STD patients are rising but are still low among pregnant women and army conscripts. Vietnam, at present, is still in the early phase of the HIV epidemic and has time to take effective and appropriate actions.