Acquired immunodeficiency syndrome, or AIDS, is the final, life-threatening stage of infection with any of the human immunodeficiency viruses (HIV-1, its many subtypes, or HIV-2), a condition in humans in which the immune system begins to fail, leading to life-threatening infections.

HIV is the human immunodeficiency virus. It is the virus that can lead to acquired immune deficiency syndrome, or AIDS. CDC estimates that about 56,000 people in the United States contracted HIV in 2006.

There are two types of HIV, HIV-1 and HIV-2. In the United States, unless otherwise noted, the term “HIV” primarily refers to HIV-1.

Both types of HIV damage a person’s body by destroying specific blood cells, called CD4+ T cells, which are crucial to helping the body fight diseases.

Within a few weeks of being infected with HIV, some people develop flu-like symptoms that last for a week or two, but others have no symptoms at all. People living with HIV may appear and feel healthy for several years. However, even if they feel healthy, HIV is still affecting their bodies. All people with HIV should be seen on a regular basis by a health care provider experienced with treating HIV infection. Many people with HIV, including those who feel healthy, can benefit greatly from current medications used to treat HIV infection. These medications can limit or slow down the destruction of the immune system, improve the health of people living with HIV, and may reduce their ability to transmit HIV. Untreated early HIV infection is also associated with many diseases including cardiovascular disease, kidney disease, liver disease, and cancer. Support services are also available to many people with HIV. These services can help people cope with their diagnosis, reduce risk behavior, and find needed services.

AIDS is the late stage of HIV infection, when a person’s immune system is severely damaged and has difficulty fighting diseases and certain cancers. Before the development of certain medications, people with HIV could progress to AIDS in just a few years. Currently, people can live much longer – even decades – with HIV before they develop AIDS. This is because of “highly active” combinations of medications that were introduced in the mid 1990s.

No one should become complacent about HIV and AIDS. While current medications can dramatically improve the health of people living with HIV and slow progression from HIV infection to AIDS, existing treatments need to be taken daily for the rest of a person’s life, need to be carefully monitored, and come with costs and potential side effects. At this time, there is no cure for HIV infection.1


HIV is transmitted from person to person sexually (including via anal, oral, and vaginal intercourse, both heterosexually and homosexually), through contact with blood (mainly via equipment used to inject illicit drugs and, rarely, via medical uses of blood), and perinatally (from mother to fetus or newborn during pregnancy, labor, and delivery, or after birth through breast-feeding).

Which Body Fluids Contain HIV?

HIV lives and reproduces in blood and other body fluids. We know that the following fluids can contain high levels of HIV:

  • Blood
  • Semen (cum)
  • Pre-seminal fluid (pre-cum)
  • Breast milk
  • Vaginal fluids
  • Rectal (anal) mucous

Other body fluids and waste products-like feces, nasal fluid, saliva, sweat, tears, urine, or vomit – don’t contain enough HIV to infect you, unless they have blood mixed in them and you have significant and direct contact with them.

Healthcare workers may be exposed to some other body fluids with high concentrations of HIV, including:

  • Amniotic fluid
  • Cerebrospinal fluid
  • Synovial fluid2

HIV Risk Factors

HIV is found in the blood, semen, or vaginal fluid of someone who is infected with the virus. You may be at increased risk of becoming infected with HIV if you

  • Engage in anal, vaginal, or oral sex with men who have sex with men, multiple partners, or anonymous partners without using a condom
  • Inject drugs or steroids where needles/syringes are shared
  • Have a sexually transmitted disease, such as syphilis, genital herpes, chlamydia, gonorrhea, bacterial vaginosis, or trichomoniasis
  • Have been diagnosed with hepatitis, tuberculosis, or malaria
  • Exchange sex for drugs or money
  • Are exposed to the virus as a fetus or infant before or during birth or through breastfeeding from a mother infected with HIV
  • Received a blood transfusion or clotting factor in the United States anytime from 1978 to 1985
  • Engage in unprotected sex with someone who has any of the risk factors listed above

Quick Facts About HIV Transmission

  • HIV cannot survive for very long outside of the body
  • HIV cannot be transmitted through routine daily activities such as using a toilet seat, sharing food utensils or drinking glasses, shaking hands, or through kissing.
  • The virus can only be transmitted from person to person, not through animals or insect bites
  • People infected with HIV who are taking antiretroviral therapy can still infect others through unprotected sex and needle-sharing3


CDC estimates 1.2 million people in the United States (US) are living with HIV infection. One in five (20%) of those people are unaware of their infection. Despite increases in the total number of people in the US living with HIV infection in recent years, the annual number of new HIV infections has remained relatively stable. However, new infections continue at far too high of a level, with approximately 50,000 Americans becoming infected with HIV each year.

In 2009, an estimated 42,011 people were diagnosed with HIV infection in the 40 states with confidential name-based HIV infection reporting since at least January 2006. In that same year, an estimated 34,247 people throughout the US (50 states and the District of Columbia) were diagnosed with AIDS. Since the epidemic began, an estimated 1,108,611 people in the US have been diagnosed with AIDS.

More the 16,000 people with AIDS were estimated to have died in 2008, and nearly 594,500 people in the US have died since the epedemic began. 34 million people were living with HIV at the end of 2010.4

What is the link between STDs and HIV infection?

Individuals who are infected with STDs are at least two to five times more likely than uninfected individuals to acquire HIV infection if they are exposed to the virus through sexual contact. In addition, if an HIV-infected individual is also infected with another STD, that person is more likely to transmit HIV through sexual contact than other HIV-infected persons (Wasserheit, 1992).

There is substantial biological evidence demonstrating that the presence of other STDs increases the likelihood of both transmitting and acquiring HIV.

How can STD treatment slow the spread of HIV infection?

Evidence from intervention studies indicates that detecting and treating STDs may reduce HIV transmission.

  • STD treatment reduces an individual’s ability to transmit HIV. Studies have shown that treating STDs in HIV-infected individuals decreases both the amount of HIV in genital secretions and how frequently HIV is found in those secretions (Fleming, Wasserheit, 1999).
  • Herpes can make people more susceptible to HIV infection, and it can make HIV-infected individuals more infectious. It is critical that all individuals, especially those with herpes, know whether they are infected with HIV and, if uninfected with HIV, take measures to protect themselves from infection with HIV.
  • Among individuals with both herpes and HIV, trials are underway studying if treatment of the genital herpes helps prevent HIV transmission to partners.5


The symptoms of HIV and AIDS vary, depending on the phase of infection.

Primary infection

The majority people infected by HIV develop a flu-like illness within a month or two after the virus enters the body. This illness, known as primary or acute HIV infection, may last for a few weeks. Possible symptoms include:

  • Fever
  • Muscle soreness
  • Rash
  • Headache
  • Sore throat
  • Mouth or genital ulcers
  • Swollen lymph glands, mainly on the neck
  • Joint pain
  • Night sweats
  • Diarrhea

Although the symptoms of primary HIV infection may be mild enough to go unnoticed, the amount of virus in the blood stream (viral load) is particularly high at this time. As a result, HIV infection spreads more efficiently during primary infection than during the next stage of infection.

Clinical latent infection

In some people, persistent swelling of lymph nodes occurs during clinical latent HIV. Otherwise, there are no specific signs and symptoms. HIV remains in the body, however, as free virus and in infected white blood cells.

Clinical latent infection typically lasts 8 to 10 years. A few people stay in this stage even longer, but others progress to more-severe disease much sooner.

Early symptomatic HIV infection

As the virus continues to multiply and destroy immune cells, you may develop mild infections or chronic symptoms such as:

  • Fever
  • Fatigue
  • Swollen lymph nodes
  • Diarrhea
  • Weight loss
  • Cough and shortness of breath

Progression to AIDS

If you receive no treatment for your HIV infection, the disease typically progresses to AIDS in about 10 years. By the time AIDS develops, your immune system has been severely damaged, making you susceptible to opportunistic infections — diseases that wouldn’t trouble a person with a healthy immune system. The signs and symptoms of some of these infections may include:

  • Soaking night sweats
  • Shaking chills or fever higher than 100 F (38 C) for several weeks
  • Cough and shortness of breath
  • Chronic diarrhea
  • Persistent white spots or unusual lesions on your tongue or in your mouth
  • Headaches
  • Persistent, unexplained fatigue
  • Blurred and distorted vision
  • Weight loss
  • Skin rashes or bumps

When to see a doctor

If you think you may have been infected with HIV or are at risk of contracting the virus, seek medical counseling as soon as possible.6

Test and Diagnosis

HIV is most commonly diagnosed by testing your blood or saliva for the presence of antibodies to the virus. Unfortunately, these types of HIV tests aren’t accurate immediately after infection because it takes time for your body to develop these antibodies — usually up to 12 weeks. In rare cases, it can take up to six months for an HIV antibody test to become positive.

A newer type of test checks for HIV antigen, a protein produced by the virus immediately after infection. This test can confirm a diagnosis within days of infection. An earlier diagnosis may prompt people to take extra precautions to prevent transmission of the virus to others.7


As of 2001, all of the more than seventeen antiviral drugs used to treat HIV infection act by interfering with one of the enzymes that HIV needs to complete its life cycle. No treatments result in a cure for HIV infection.

The antiviral drugs prevent HIV from growing and further damaging the host’s immune system. Thus, the goal of treatment is to preserve the patient’s health. Patients must take several antiviral drugs daily. Research on more and better antiviral drugs, and on methods to reconstitute the impaired immune system, is ongoing. A key part of treatment is the prevention of opportunistic infections with specific vaccines and antibiotics.


Prevention of HIV infections is deceptively simple: Refrain from having sexual contact and from sharing drug-injecting paraphernalia with anyone who is infected.

Consistent use of male latex condoms can help protect against HIV infection.8

Currently, there is no vaccine to prevent HIV infection nor is there a cure for HIV/AIDS. To reduce your risk of becoming infected with HIV or transmitting the virus to others

  • Get tested regularly for HIV
  • Practice abstinence
  • Remain faithful to your spouse or partner
  • Consistently use male latex or female polyurethane condoms
  • Do not share needles

Condoms, even when used correctly and 100 percent of the time during sexual activity, are ultimately an unreliable prevention against the transmission of HIV. The most recent and best studies show that condoms only provide protection against the HIV virus during vaginal intercourse 85 percent of the time. With anal intercourse, the condom prevention rate drops to only about 50 percent. To date, there is no evidence showing condoms offer any prevention when used during oral sex.


The research effort to develop a vaccine to prevent HIV infection has been intense, but the biologic obstacles to success are immense and unprecedented.

Because HIV permanently infects cells of the immune system, infection of a single cell results in lifelong infection for the host. Thus, a completely effective vaccine would need to prevent even a single cell from becoming infected. No such vaccine exists for any infection, so HIV will require a new vaccine paradigm.

Possible lines of research include stimulating the immune system to detect and eliminate HIV-infected cells, or genetically transforming the HIV in an infected person so as to render it nonvirulent.


Further information on HIV and AIDS is widely available in many user-friendly and scholarly formats.

The Internet is a rich source of information, with sites sponsored by public health agencies, such as the Joint United Nations Programme on HIV/AIDS ( and the Centers for Disease Control and Prevention (, which are particularly recommended.

Several texts, popular books, and scholarly journals have been devoted exclusively to AIDS public health issues and scientific research.

The first of December has been designated World AIDS Day, and many governments, schools, and organizations sponsor community and educational events to coincide with that date each year.9











9 Adapted from “AIDS.” Encyclopedia of Public Health, The Gale Group, Inc, 2002., accessed January 22, 2007.

Feldman, E. A., and Bayer, R. (1999). Blood Feuds: AIDS, Blood, and the Politics of Medical Disaster. New York: Oxford University Press.

Garrett, L. (1994). The Coming Plague: Newly Emerging Diseases in a World Out of Balance. New York: Farrar, Straus and Giroux.

Mann, J. M.; Tarantola, D.; and the Global AIDS Policy Coalition, eds. (1998). AIDS in the World II/Global Dimensions, Social Roots, and Responses. New York: Oxford University Press.

Shilts, R. (1987). And the Band Played On: Politics, People, and the AIDS Epidemic. New York: St. Martin’s Press.

HIV in the United States – CDC 2011,