The AIDS Education and Training Centers National Resource Center explains that a classification system for HIV exists to help clinicians track the progression of the HIV infection. Two types of classification systems exist: one from the Centers for Disease Control and Prevention and one from the World Health Organization. CDC uses the CD4 count to classify the stage of HIV, whereas the World Health Organization's classification system uses other identifying measures, such as symptoms.
Acute HIV
The first classification for HIV is the acute HIV stage, also referred to as primary HIV. MedlinePlus explains that a person develops acute HIV two to four weeks after exposure to the virus. The World Health Organization classification system notes that patients with acute HIV may have no symptoms or have symptoms resembling the flu. These symptoms can last for one to four weeks. Symptoms that may occur during an acute HIV infection include a headache, sore throat, fatigue, swollen glands and fever. Patients may also experience a rash, muscle stiffness, decreased appetite and ulcers in the esophagus or mouth.
Asymptomatic HIV
After the acute HIV infection, patients may progress to an asymptomatic HIV infection. The AIDS Education and Training Centers National Resource Center points out that asymptomatic HIV falls under Clinical Category A for CDC's classification system and as Clinical Stage 1 under the World Health Organization's classification system. If a person has an asymptomatic HIV infection, he does not have any symptoms. MedlinePlus notes that patients may not have symptoms for up to 10 years or more. Even though the patient does not show symptoms, she may pass the virus on to other people through sexual intercourse or needle exchange.
Early Symptomatic HIV
Some HIV patients may show symptoms of the virus before it progresses into AIDS. Under the different classification systems, early symptomatic HIV is considered Clinical Category B with CDC's system and Clinical Stages 2 and 3 under the World Health Organization's classification system. Clinical Stage 2 contains more mild symptoms, whereas Clinical Stage 3 contains more advanced symptoms. Symptoms of early symptomatic HIV include persistent diarrhea, fatigue and fever. Patients may also have sweating, joint pain or peripheral neuropathy, a condition that affects sensation, movement and involuntary functions. During this stage of HIV, patients may develop oral thrush, seborrheic dermatitis or molluscum contagiosum, according to MedlinePlus.
AIDS
The final stage of HIV is AIDS. CDC classifies this stage as Clinical Category C, in which the patient has a CD4 count of below 200 cells/mm3. Under the World Health Organization's classification, AIDS is Clinical Stage 4, which contains more severe symptoms. Symptoms of AIDS result from the opportunistic infections, which are infections that develop due to a weakened immune system. Symptoms include weakness, weight loss, chills, swollen glands and night sweats. The types of opportunistic infections that may develop depend on the CD4 cell count. Opportunistic infections may develop during the early symptomatic HIV infection as well. For example, MedlinePlus notes that herpes zoster can develop when the CD4 cell count is below 350 cells/mm3. When the cell count is below 100 cells/mm3, AIDS dementia, wasting syndrome and cryptococcal meningitis may occur. If a CD4 cell count is below 50 cells/mm3, patients may develop mycobacterium avium or a cytomegalovirus infection.
