Also called: Acquired
immunodeficiency syndrome, HIV,
Human immunodeficiency virus
AIDS stands for acquired immunodeficiency syndrome. It is the most advanced stages of infection with the human immunodeficiency virus (HIV). HIV is a virus that kills or damages cells of the body's immune system.
HIV most often spreads through unprotected sex with an infected person. AIDS may also spread by sharing drug needles or through contact with the blood of an infected person. Women can give it to their babies during pregnancy or childbirth.
The first signs of HIV infection may be swollen glands and flu-like symptoms. These may come and go a month or two after infection. Severe symptoms may not appear until months or years later.
A blood test can tell if you have HIV infection. Your health care provider can perform the test, or call the National AIDS hotline for a referral at (800) 342-AIDS (1-800-342-2437). There is no cure, but there are many medicines to fight both HIV infection and the infections and cancers that come with it. People can live with the disease for many years.
Since 1981, more than 980,000 cases of AIDS have been reported in the United States to the Centers for Disease Control and Prevention (CDC). According to CDC, more than 1,000,000 Americans may be infected with HIV, one-quarter of whom are unaware of their infection. The epidemic is growing most rapidly among minority populations and is a leading killer of African-American males ages 25 to 44. According to CDC, AIDS affects nearly seven times more African Americans and three times more Hispanics than whites. In recent years, an increasing number of African-American women and children are being affected by HIV/AIDS.
How HIV Causes AIDS
HIV destroys CD4 positive (CD4+) T cells, which are white blood cells crucial to maintaining the function of the human immune system. As the virus attacks those cells, the person infected with HIV is less equipped to fight off infection and disease ultimately resulting in the development of AIDS.
Most people who are infected with HIV can carry the virus for years before sufficient damage to the immune system results in the development of AIDS. However, there is a strong connection between high levels of HIV in the blood and the decline in CD4+ T cells and the development of AIDS. Antiretroviral medicines can reduce the amount of virus in the body, preserve CD4+ T cells and dramatically slow the destruction of the immune system.
The HIV-AIDS Connection
The acquired immunodeficiency syndrome (AIDS) was first recognized in 1981 and has since become a major worldwide pandemic. Abundant evidence indicates that AIDS is caused by the human immunodeficiency virus (HIV) , which was discovered in 1983. By leading to the destruction and/or functional impairment of cells of the immune system, notably CD4+ T cells, HIV progressively destroys the body's ability to fight infections and certain cancers.
Why is there overwhelming scientific consensus that HIV causes AIDS?
Before HIV infection became widespread in the human population, AIDS-like syndromes occurred extremely rarely, and almost exclusively in individuals with known causes of immune suppression, such as chemotherapy and underlying cancers of certain types. A marked increase in unusual infections and cancers characteristic of severe immune suppression was first recognized in the early 1980s in homosexual men who had been otherwise healthy and had no recognized cause for immune suppression. An infectious cause of AIDS was suggested by geographic clustering of cases, links among cases by sexual contact, mother-to-infant transmission, and transmission by blood transfusion. Isolation of the HIV from patients with AIDS strongly suggested that this virus was the cause of AIDS. Since the early 1980s, HIV and AIDS have been repeatedly linked in time, place and population group; the appearance of HIV in the blood supply has preceded or coincided with the occurrence of AIDS cases in every country and region where AIDS has been noted. Individuals of all ages from many risk groups – including men who have sex with men, infants born to HIV-infected mothers, heterosexual women and men, hemophiliacs, recipients of blood and blood products, healthcare workers and others occupationally exposed to HIV-tainted blood, and male and female injection drug users – have all developed AIDS with only one common denominator: infection with HIV.
HIV destroys CD4+ T cells, which are crucial to the normal function of the human immune system. In fact, depletion of CD4+ T cells in HIV-infected individuals is an extremely powerful predictor of the development of AIDS. Studies of thousands of individuals have revealed that most HIV-infected people carry the virus for years before enough damage is done to the immune system for AIDS to develop; however, with time, a near-perfect correlation has been found between infection with HIV and the subsequent development of AIDS. Recently developed, sensitive tests have shown a strong correlation between the amount of HIV in the blood and the subsequent decline in CD4+ T cell numbers and development of AIDS. Furthermore, reducing the amount of virus in the body with anti-HIV drugs can slow this immune destruction.
Additional documents and resources covering these issues and other evidence that HIV causes AIDS.
Transmission
HIV is spread most often through unprotected sex with an infected partner. The virus can enter the body through the lining of the vagina, vulva, penis, rectum, or mouth during sex.
Risky behavior
HIV can infect anyone who practices risky behaviors such as
Sharing drug needles or syringes
Having sexual contact, including oral sexual contact, with an infected person without using a condom
Having sexual contact with someone whose HIV status is unknown
Infected blood
HIV also is spread through contact with infected blood. Before donated blood was screened for evidence of HIV infection and before heat-treating techniques to destroy HIV in blood products were introduced, HIV was transmitted through transfusions of contaminated blood or blood components. Today, because of blood screening and heat treatment, the risk of getting HIV from blood transfusions is extremely small.
Contaminated needles
HIV is often spread among injection drug users when they share needles or syringes contaminated with very small quantities of blood from someone infected with the virus.
It is rare for a patient to be the source of HIV transmitted to a healthcare provider or vice versa by accidental sticks with contaminated needles or other medical instruments.
Mother to child
Women can transmit HIV to their babies 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 be spread to babies through the breast milk of mothers infected with the virus.
If the mother takes certain drugs during pregnancy, she can significantly reduce the chances that her baby will get infected with HIV.
If healthcare providers treat HIV-infected pregnant women and deliver their babies by cesarean section, the chances of the baby being infected can be reduced to a rate of 1 percent.
HIV infection of newborns has been almost eradicated in the United States because of appropriate treatment.
A study sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) in Uganda found a highly effective and safe drug for preventing transmission of HIV from an infected mother to her newborn. Independent studies have also confirmed this finding. This regimen is more affordable and practical than any other examined to date. Results from the study show that a single oral dose of the antiretroviral drug nevirapine (NVP) given to an HIV-infected woman in labor and another to her baby within 3 days of birth reduces the transmission rate of HIV by half compared with a similar short course of AZT (azidothymidine).
Saliva
Although researchers have found HIV in the saliva of infected people, there is no evidence that the virus is spread by contact with saliva. Laboratory studies reveal that saliva has natural properties that limit the power of HIV to infect, and the amount of virus in saliva appears to be very low. Research studies of people infected with HIV have found no evidence that the virus is spread to others through saliva by kissing.
The lining of the mouth, however, can be infected by HIV, and instances of HIV transmission through oral intercourse have been reported.
Scientists have found no evidence that HIV is spread through sweat, tears, urine, or feces.
Casual contact
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.
Sexually transmitted infections
People with a sexually transmitted infection, such as syphilis, genital herpes, chlamydia, gonorrhea, or bacterial vaginosis, may be more susceptible to getting HIV infection during sex with infected partners.
