Human Immunodeficiency Virus (HIV)

The human immunodeficiency virus (HIV) kills or damages the body's immune system. Acquired immunodeficiency syndrome (AIDS) is the most advanced stage of infection with HIV.

Human Immunodeficiency Virus (HIV) Overview

Reviewed: May 19, 2014
Updated: 

The human immunodeficiency virus (HIV) kills or damages the body's immune system. By damaging your immune system, HIV interferes with your body's ability to fight the organisms that cause disease. As the immune system weakens, the body is at risk of getting life-threatening infections and cancers. Once a person has the virus, it stays inside the body for life.

Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by HIV.

HIV is often transmitted through sexual contact or through contact with an infected person’s blood. It can also be spread from mother to child during pregnancy, childbirth, or breast-feeding.

The first signs of HIV infection may be swollen glands and flu-like symptoms. These may come and go a month or 2 after infection. Severe symptoms may not appear until months or years later. HIV will eventually progress and weakens your immune system to the point that you have AIDS.

There is no cure for HIV/AIDS, but there are medications that can dramatically slow the progression of the disease and people with HIV can live longer, healthier lives than in the past.

Human Immunodeficiency Virus (HIV) Symptoms

The symptoms of HIV infection and AIDS vary, depending on the phase of infection. Symptoms related to acute HIV infection (when a person is first infected) are often flu-like. They include:

  • Diarrhea
  • Fever
  • Headache
  • Mouth sores, including yeast infection (thrush)
  • Muscle stiffness or aching
  • Night sweats
  • Rashes of different types
  • Sore throat
  • Swollen lymph glands

Many people have no symptoms when they are diagnosed with HIV.

Acute HIV infection progresses over a few weeks to months to become an asymptomatic (no symptoms) HIV infection. This stage can last 10 years or longer. During this period, the person can still spread the virus to others.

If not treated, almost all people infected with HIV will develop AIDS. People with AIDS have had their immune system damaged by HIV, and they are at very high risk of getting infections that are uncommon in people with a healthy immune system. These infections are called opportunistic infections.

Common symptoms of HIV/AIDS-related infections are:

  • Chills
  • Chronic diarrhea
  • Persistent white spots or unusual lesions on your tongue or in your mouth
  • Recurring fever
  • Skin rashes or bumps
  • Sweats (particularly at night)
  • Swollen lymph glands
  • Weakness
  • Persistent, unexplained fatigue
  • Weight loss

Human Immunodeficiency Virus (HIV) Causes

HIV is spread (transmitted) person-to-person in any of the following ways:

  • Through sexual contact -- including oral, vaginal, and anal sex
  • Through blood -- by blood transfusions (now extremely rare in the U.S.) or more often by needle sharing during illicit drug use
  • From mother to child -- a pregnant woman can spread the virus to her fetus through their shared blood circulation, or a nursing mother can pass it to her baby through her breast milk

HIV cannot survive for very long outside of the body. It 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 at high risk of getting HIV include:

  • Drug users who inject and then share needles
  • Infants born to mothers with HIV who did not receive HIV treatment during pregnancy
  • People who have unprotected sex, especially with people who have other high-risk behaviors, are HIV-positive, or have AIDS
  • People who received blood transfusions or clotting products between 1977 and 1985, before screening for the virus became standard practice
  • Sexual partners of those who engage in high-risk activities (such as injection drug use or anal sex)

After HIV infects the body, the virus has been found in many different fluids and tissues in the body. Only blood, semen, fluids from the vagina, and breast milk have been shown to transmit infection to others.

The virus may also be found in saliva, tears, nervous system tissue, and spinal fluid.

People infected with HIV who are receiving therapy can still infect others through unprotected sex and needle-sharing.

Anyone of any age, race, sex, or sexual orientation can be infected, but you are at greatest risk of contracting HIV/AIDS if you:

  • Have unprotected sex. Unprotected sex means having sex without using a new latex or polyurethane condom every time. Anal sex is more risky than is vaginal sex. The risk increases if you have multiple sexual partners.
  • Have another STI. Many sexually transmitted infections (STIs) produce open sores on your genitals. These sores allow HIV to easily enter your body.
  • Use intravenous drugs. People who use intravenous drugs often share needles and syringes. This exposes them to droplets of other people's blood.
  • Are an uncircumcised man. Studies indicate that lack of circumcision increases the risk of heterosexual transmission of HIV.

Human Immunodeficiency Virus (HIV) Diagnosis

HIV infection is most commonly diagnosed by testing your blood or saliva for antibodies to the virus. These antibodies develop up to 12 weeks after infection with HIV, so a test before this time may not be accurate.

People with AIDS usually have regular blood tests to check their immune system function and guide therapy.

Living With Human Immunodeficiency Virus (HIV)

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:

  • Do not use illegal drugs and do not share needles or syringes.
  • Avoid contact with another person's blood. If possible, wear protective clothing, masks, and goggles when caring for people who are injured.
  • Do not donate blood, plasma, body organs, or sperm.

HIV-positive women who plan to get pregnant should talk to their health care provider about the risk to their unborn child. They should also discuss methods to prevent their baby from becoming infected, such as taking medicines during pregnancy. Breastfeeding should be avoided to prevent passing HIV to infants through breast milk.

Safer sex practices, such as using latex condoms, are effective in preventing the spread of HIV. But there is a risk of getting the infection, even with the use of condoms. Abstinence is the only sure way to prevent sexual transmission of HIV.

Once diagnosed with HIV or AIDs, people can take an active role in their own care to stay healthy longer:

  • Eat healthy foods. Emphasize fresh fruits and vegetables, whole grains, and lean protein. Healthy foods help keep you strong, give you more energy, and support your immune system.
  • Avoid certain foods. Foodborne illnesses can be especially severe in people who are infected with HIV. Avoid unpasteurized dairy products, raw eggs, and raw seafood such as oysters, sushi, or sashimi. Cook meat until itis well-done.
  • Get immunizations. These may prevent infections such as pneumonia and the flu. Make sure the vaccines do not contain live viruses, which can be dangerous for people with weakened immune systems.
  • Take care with companion animals. Some animals may carry parasites that can cause infections in people who are HIV-positive. Cat feces can cause toxoplasmosis, reptiles can carry salmonella, and birds can carry the fungus cryptococcus or histoplasmosis. Wash hands thoroughly after handling pets or emptying a litter box.
  • Joining a support group where members share common experiences and problems can often help lower the emotional stress of having a long-term illness.

Human Immunodeficiency Virus (HIV) Treatments

There is no cure for HIV infection at this time, but treatments are available to manage symptoms and reduce how much the virus copies itself (replicates). Treatment can also improve the quality and length of life for those who have already developed symptoms. There are 5major types of medicines:

These medicines help people with HIV, but they are not perfect. They do not cure HIV/AIDS. People with HIV infection still have the virus in their bodies and they can still spread HIV to others through unprotected sex and needle sharing, even when they are taking their medicines.


Human Immunodeficiency Virus (HIV) Prognosis