AIDS (Acquired Immunodeficiency Syndrome)
A person who has been infected by the human immunodeficiency virus (HIV) is diagnosed as having AIDS after developing one of the illnesses that the Centers for Disease Control has identified as an indicator of AIDS. An HIV-positive person who has not had any serious illnesses also can receive an AIDS diagnosis based on certain blood tests (CD4+ counts).
When HIV weakens the immune system, "opportunistic" infections can take advantage of this weakened state and cause illness. Opportunistic infections include Kaposi's sarcoma and pneumocystis carinii pneumonia. Many of these illnesses are readily controlled by a healthy immune system.
Having been infected with HIV (being HIV positive and having HIV antibodies in the blood) is not the same as having AIDS.
Persons who are infected with HIV may not know it. Some people experience flu-like symptoms, such as fever, headache, muscles and joints, stomachache, swollen lymph glands or a skin rash that lasts one to two weeks.
The virus multiplies in the body for a few weeks or even months before the immune system responds. During this time a person will not test positive for HIV infection but does have the ability to infect others.
The virus uses CD4 T cells, a type of white blood cell that fights infection, to make copies of itself. This process destroys the CD4 T cells, weakening the immune system. Without treatment, a person might experience fevers, night sweats, diarrhea or swollen lymph nodes for several weeks.
HIV progresses to AIDS when:
- An HIV-infected individual's CD4 T cell count drops below 200 cells/mm
- An HIV-infected individual develops an illness that is very unusual in someone who is not HIV-positive
Opportunistic illnesses that are typical of AIDS include:
- Pneumocystis carinii pneumonia, a lung infection
- Kaposi's sarcoma, a skin cancer
- Cytomegalovirus, an infection that usually affects the eyes
- Candida, a fungal infection that can cause thrush, a white film and infections in the throat or vagina
- Invasive cervical cancer
AIDS-related diseases also include serious weight loss and brain tumors.
AIDS varies from person to person. Some people die soon after getting infected while others live relatively normal lives for many years, even after being officially diagnosed with AIDS.
Causes and Risk Factors
AIDS is caused by infection with HIV. HIV infection has been the only common factor shared by persons with AIDS throughout the world, regardless of sexual preferences, lifestyle, health, sexual practices, age or gender.
While much still needs to be learned about HIV and AIDS, certain factors can put a person at higher risk of acquiring it, including:
- Exposure to HIV infected body fluids, including blood, semen, vaginal fluid, breast milk or other fluids that usually only present a risk to healthcare workers (cerebrospinal fluid surrounding the brain and spinal cord, synovial fluid surrounding bone joints and amniotic fluid surrounding a fetus)
- Sharing of needles or syringes with someone who is infected
- Being born to or breast-fed by a woman who is HIV-positive
- Not practicing safer sex (use of a latex condom)
HIV does not reproduce outside of a living host, nor does it survive well in the environment. It cannot be spread through casual contact, such as occurs in offices, business settings or even most homes. There is no evidence that it can be spread through insects.
It is not yet known what the origins of the HIV virus are. The earliest known case of HIV was from a blood sample collected in 1959 from a man in the Democratic Republic of Congo. The virus has existed in the United States since at least the mid- to late-1970s.
In 1983 scientists isolated HIV-1. Three years later, a second type, HIV-2, was isolated from AIDS patients in West Africa. Both spread the same way, but HIV-2 appears to develop more slowly, be milder and have a shorter period of time when it is infectious compared to HIV-1. HIV-2 is rare in the United States.
While receiving donated blood or transfusions used to be a source of HIV infection, all U.S. blood donations have been tested for a combination of HIV-1 and HIV-2 since 1992.
When infected with HIV, a person's body develops antibodies against the infection, and these antibodies become detectable in laboratory tests within three months. After taking a medical history and performing a physical examination, a doctor may want to do other tests, including:
- A complete blood count
- A blood chemistry profile
- A test for hepatitis B and C
- A blood test to measure CD4 T cells. Because the virus uses these cells to copy itself, killing the CD4 T cells in the process, a low CD4 T cell count is an indicator of the progress of the disease
- A blood test to measure viral load or the amount of HIV in a sample of blood. Those with a high viral load usually develop AIDS faster than those with a low viral load.
- A syphilis screening
- A tuberculin skin test
- A toxoplasma antibody test
Women should also have a gynecological exam with a Pap smear and a pregnancy test.
At present, there is no way to cure HIV infection or remove the virus from the body. However, drug therapy can slow down the virus and the damage that it does to the immune system. Other drugs are available to prevent or treat opportunistic infections that can be life threatening to the person with HIV infection.
In deciding when to start HIV treatment, several factors need to be taken into consideration:
- Results of the CD4 T cell count
- Results of the viral load test
- The patient's willingness to consistently follow the drug therapy. HIV treatment plans are complicated and may involve taking 25 or more pills each day. Some must be taken on an empty stomach, while others are taken with meals. The treatment may need to be continued for the patient's lifetime.
- Whether the patient has AIDS or advanced HIV disease
Persons who are found to be HIV-positive are usually given drugs (antiretroviral therapy) to keep them healthy. Once treatment begins, an HIV-positive person's viral load normally drops to an undetectable level within 16 to 20 weeks. However, the drug treatment is complicated, and different people get different results. Treatment can help people at all stages of HIV disease stay healthy. Following a drug therapy plan is very important as drug resistance often develops when doses are skipped.
Early therapy can help HIV-infected individuals achieve and maintain control of viral loads, can delay or prevent weakened immunity and can lower the risk of drug resistance. Early therapy does, however, pose the potential for serious side effects, limited future therapy options and a negative impact on the patient's quality of life.
Delayed therapy may avoid quality of life impacts and side effects. However, delayed therapy may also result in permanent immune system damage from the virus.
HIV drugs are designed to slow the reproduction of the virus. The recommended treatment for HIV is a combination of three or more HIV drugs. This treatment is called highly active anti-retroviral therapy or HAART. The three types of FDA-approved antiretroviral drugs are:
- Nucleoside/neucleotide reverse transcriptase inhibitors (NRTIs)
- Protease inhibitors (PIs)
- Non-nucleoside reserve transcriptase inhibitors (NNRTIs)
Possible side effects of this type of therapy include:
- Liver problems
- Fat maldistribution
- High cholesterol
- Increased bleeding in patients with hemophilia
- Decreased bone density
- Skin rash
Symptoms, such as fever, nausea or fatigue, could be signs of more serious problems, and any side effects experienced should always be discussed with a doctor. Viral loads should be tested two to eight weeks after starting treatment and every three to four months thereafter to make sure that the therapy is still working. The patient's CD4 T cell counts should be done every three to six months during treatment.
Persons who are HIV-positive who have not started drug therapy should have a viral load test every three to four months and a CD4 T cell count every three to six months.
HIV and Pregnancy
Pregnancy presents special challenges in the treatment of HIV. Pregnant women should not take some drugs that are usually given to persons who are infected with HIV because they may cause birth defects.
It is not yet possible to predict whether a woman who is HIV-positive will pass the infection to her baby. Studies indicate that taking zidovudine (AZT) reduces the risk of passing HIV to the baby by almost 70%. It is also important for a pregnant woman with HIV to get regular prenatal care and stick with her HIV drug treatment plan.