HIV and AIDS: transmission and prevalence
Human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome, or AIDS, is found primarily in blood, semen and vaginal secretions of infected persons. HIV is spread by sexual contact (vaginal, anal or oral sex) with an infected person, by needle-sharing among injecting drug users, and through transfusions of infected blood and blood clotting factors.
AIDS is a severe, life-threatening illness. The incubation period for AIDS is very long and variable, ranging from a few months to many years. Some individuals infected with HIV have remained without symptoms of AIDS for more than a decade.
Babies born to HIV-infected women may become infected before, during, or shortly after birth through breast feeding.
How is HIV transmitted?
Scientific studies have revealed no evidence that HIV is transmitted by air, food, water, insects, inanimate objects or casual contact. Even though HIV antibodies are normally detected by a test within a few weeks to 6 months after infection, the period between infection and development of disease symptoms (incubation period) may be 10 years or longer.
Is there a cure for AIDS?
Although there is no cure for AIDS, treatments for HIV infection and preventive medicines for many opportunistic diseases that characterise AIDS are available. Specific medical treatment clearly improves the health and the
survival of HIV-infected persons.
Currently, there is no vaccine available to protect against infection with HIV.
How common is AIDS?
HIV infection and AIDS have been reported worldwide. Comprehensive surveillance systems are lacking in many countries, so the true number of cases is likely to be far greater than the numbers officially reported from some areas, particularly the non-industrialised nations.
The number of persons living with HIV/AIDS as of the end of 2001 is estimated by the World Health Organization to be 40 million worldwide. Because HIV infection and AIDS are distributed globally, the risk to international travellers is determined less by their geographic destination than by their sexual and drug-using behaviours.
Last Reviewed: 11 September 2002
