HIV-1 incidence estimates using IgG-capture BED-enzyme immunoassay from surveillance sites of injection drug users in three cities of China.

Objective: To detect recent infection in injection drug users (IDU) using the HIV-1 subtypes B, E, and D IgG-capture enzyme immunoassay (BED-CEIA) and estimate HIV-1 incidence in the IDU population in three cities of China.

Design: HIV-1-positive samples from IDU surveillance sentinel sites were collected for BED-CEIA, including 215 from city C (2001-2006), 433 from city D (2005), and 912 from city E (2000-2003). All 1560 samples were confirmed HIV positive with Western blot or alternative strategy.

Methods: HIV-1 incidence was calculated with BED-CEIA statistics software.

Results: City C: Annualized HIV-1 incidence among IDU of surveillance sentinel sites was 0.57-0.93% from 2000 to 2001, and approximately 1.0% from 2004 to 2006. City D: In IDU surveillance sentinel sites in 2005, the HIV-1 incidence was estimated to be 9.6%, whereas the incidence in all drug users was 2.1%. City E: IDU sentinel surveillance indicated a slight decrease in HIV-1 incidence from 9.2% in 2000 to 7.9% in 2003.

Conclusion: The HIV-1 incidence in IDU in city C was stable and relatively low. In contrast, there is a high HIV-1 incidence among IDU in cities D and E. The adjusted BED-CEIA estimated incidence rates indicate clearly that interventions must be strengthened continuously in IDU, especially in two Chinese cities.