In its early stages, HIV infection has no

In its early stages, HIV infection has no symptoms or causes only a flu-like illness with many of the following symptoms: fever, sore throat, rash, nausea and vomiting, diarrhea, fatigue, swollen lymph nodes, muscle aches, headaches and joint pain. Although 50% to 90% of people experience symptoms within the first few weeks of contracting HIV infection, most people and doctors dismiss the illness as a routine cold or flu. In a small number of cases, this early stage of infection may progress to meningitis (inflammation of membranes covering the brain) or other severe flulike symptoms that require hospitalization.

As the number of CD4 cells drops below normal (800 to 1,200 cells per cubic millimeter of blood), the person may begin to develop swollen lymph nodes and skin problems, such as seborrheic dermatitis (dandruff), new or worsening psoriasis and minor infections. Ulcers can develop around the mouth.

Over the next few years, as CD4 cells continue to die, skin problems and mouth ulcers develop more often. Recurring herpes and varicella-zoster infections (shingles) can occur. Many people develop diarrhea, fever, unexplained weight loss, joint and muscle pain, and fatigue. Old tuberculosis infections may reactivate even before AIDS develops. (Tuberculosis is one of the most common AIDS-related infections in the developing world.)

Finally, with further decreases in the levels of CD4 cells, the person develops AIDS. In an HIV-infected person, some signs that AIDS has developed are:

• The CD4 count has decreased to 200 cells per cubic milliliter of blood or fewer.
• An infection has developed, causing certain types of pneumonia, diarrhea, eye infections or meningitis. Some of the germs that can cause these opportunistic infections include Candida fungus, cryptococcosis, cytomegalovirus, herpes simplex virus, Mycobacterium avium complex and Pneumocystis carinii. The person also can develop fungal infections specific to certain areas of the United States, such as histoplasmosis and coccidioidomycosis.
• A tumor has developed, including cervical cancer, Kaposi's sarcoma (cancer-causing round, reddish spots in the skin and mouth), certain types of non-Hodgkin's lymphoma or brain lymphoma.
• An AIDS-related brain illness has developed, including HIV encephalopathy (AIDS dementia) or progressive multifocal leukoencephalopathy.
• There is severe body wasting (HIV wasting syndrome).
• There is an AIDS-related lung illness, such as pulmonary lymphoid hyperplasia or lymphoid interstitial pneumonia (usually seen only in children).

Diagnosis

Your doctor will ask about possible HIV risk factors, such as previous sexual partners, intravenous drug use, blood transfusion and occupational exposure to blood. Your doctor will ask about a variety of symptoms, such as fever, weight loss, muscle and joint aches, fatigue and headache, and about medical problems you may have had, such as skin rashes or infections, sinusitis, pneumonia and yeast infections. This typically is followed by a complete physical examination. Your doctor will look for a thick, white coating on your tongue that may be thrush (infection with Candida fungus), skin abnormalities such as Kaposi's sarcoma or recurrent infections and other abnormalities that suggest the diagnosis of AIDS.

HIV testing can be done in your doctor's office or in an anonymous clinic. Your doctor will confirm the diagnosis of HIV infection through blood tests. The initial screening test is called enzyme linked immunosorbent assay (ELISA). It detects disease-fighting proteins in your immune system (antibodies) specific to HIV. A Western blot test, which also measures the body's response to HIV, is more accurate, and is done to confirm the diagnosis. Neither the ELISA nor Western blot is accurate immediately after exposure to the HIV virus. It can take a few months for these tests to become positive.