HIV Infection and AIDS

From the National Institute of Allergy and Infectious Diseases

    AIDS - acquired immune deficiency syndrome - was first reported in the U.S. in 1981 and has since become a major worldwide epidemic.  AIDS is caused by the human immundeficiency virus (HIV).  By killing or impairing cells of the immune system, HIV progressively destroys the body' ability to fight infections and certain cancers.  Individuals diagnosed with AIDS are susceptible to life-threatening diseases called opportunistic infection, which are caused by microbes that usually do not cause illness in healthy people.
     More than 500,000 cases of AIDS have been reported in the U.S. ince 1981, and as many as 900,000 americans may be infected with HIV.  The epidemic is growing most rapidly among minority populations and is the leading killer of African-American males.  According the U.S. Centres for Disease Control and Prevention (CDC), the prevelance of AIDS is six times higher in African Americans and three times Higher among Hispanics than among whites.

Transmission

    HIV is spread most commonly by sexual contact with an infected partner.  The virus can enter the body through the lining of the vagina, vulva, penis, rectum or mouth during sex.
     HIV also is spread through contact with infected blood.  Prior the the screening of blood for evidence of HIV infection and before the introduction in 1985 of heat-treating techniques to destroy HIV in blood products, HIV was transmitted through transfusions of contaminated blood or blood components.  Today, the risk of acquiring HIV from such transfusions is extremely small.
     HIV frequently is spread among injection drug users by sharing the needle or syringes contaminated with minute quanities of blood of someone infected with the virus.  However, transmission from patient to health-care worker or vice-versa via accidental sticks with contaminated needles or other medical instruments is rare.
     Women can transmit HIV to their fetuses during pregnancy or birth.  Approximately one-quarter to one-third of all untreated pregnant women infected with HIV will pass the infection to their babies. HIV also can spred to babies through the breast milk of mothers infected with the virus.  If the drug AZT is taken during pregnancy, the chance of transmitting HIV to the baby is reduced signifigantly.
     Although researchers have detected HIV in the saliva of infected individuals, no evidence exists that the virus is spread by contact with saliva.  Labratory studies reveal that saliva has natural compounds that inhibit the infectiousness of HIV.  Studies of people infected with HIV have found no evidence that the virus is spread to others through saliva such as kissing.  However, the risk of infection from so-called "deep kissing", involving the exchange of large amounts of saliva, is unknown.  Scientists also have found no evidence that HIV is spread through sweat, tears, urine, or feces.
     Studies of families of HIV-infected people have shown clearly that HIV is not spread through casual contact such as the sharing of food utensils, towels and bedding, swimming pools, telephones or toilet seats.  HIV is not spread by biting insects such as mosquitoes or bedbugs.
     HIV can infect anyone who practices risky behaviors such as:
           - sharing drug needles or syringes;
           - having unprotected sex with an infected person or with someone whose HIV status                          is unknown
     Having another sexually transmitted disease such as syphillis, herpes, chlamydia or gonorrhea appears to make someone more susceptible to acquiring HIV infection during sex with an infected partner.