BEIJING, Nov. 24 -- As the World AIDS Day approaches, China has launched a nationwide campaign for knowledge on HIV testing.

HIV testing enables those infected to start treatment or take preventive measures as early as possible, such as by using condoms and receiving antiretroviral therapy, according to experts.

In most cases, HIV antibodies can be detected four weeks after high-risk HIV behavior. If the testee has not engaged in any further high-risk behavior for 12 weeks and is HIV-negative, the possibility of HIV infection can be generally excluded, experts said.

Local disease control and prevention centers offer free consulting and testing services and most grassroots medical institutions and hospitals provide such services. Some universities have dispensers selling HIV antibody testers.

The 31st World AIDS Day falls on Dec. 1.

China has 820,756 people living with HIV/AIDS, and 253,031 people had died of AIDS-related diseases as of the end of June, according to a report released at the fifth National Conference on HIV/AIDS in September.