People who believe they may be infected with HIV, as well as those who know they are, can benefit from various psychological interventions. People with high-risk behaviours may have difficulty deciding whether to be tested for HIV, and psychologists can provide both information and support for these people. A significant minority of homosexual and bisexual men, intravenous drug users, and a larger proportion of heterosexual men and women with multiple partners and inconsistent users of condoms have never been tested for HIV. Indeed, an estimated 70% of people who are HIV-positive have not been tested and thus do not know their HIV status. Because HIV infection has a long incubation period, at-risk heterosexual men and women may contaminate others for years before they learn they have HIV. However, people learning of an HIV- positive test result typically react with increased anxiety, depression, anger and distress. Therefore, trained psychotherapists are needed to help such people cope with their diagnosis.