Infection with HIV is the cause of acquired immunodeficiency syndrome (AIDS), and it is a major global health problem. There are 2 virus types, HIV-1 and HIV-2. The virus is transmitted primarily by sexual contact. It can also be transmitted parenterally (through injection drug use, through blood transfusion, or at the time of organ transplant) or perinatally (in utero, intrapartum, or during breastfeeding). Men who have sex with men and patients who abuse intravenous drugs are at increased risk for this infection. The virus attacks CD4 T-lymphocytes, leading to progressive immune dysfunction.

The case definition for HIV infection for adults and adolescents includes 3 stages:

• Stage 1 for CD4 cells greater than or equal to 500 cells per microliter.
• Stage 2 for CD4 cells greater than or equal to 200 cells per microliter.
• Stage 3 (AIDS) with less than 200 cells per microliter or the presence of an AIDS-defining condition.

Diagnosis of HIV infection is made when a highly sensitive screening test and a highly specific confirmatory test are both positive. There are many approved commercial assays for HIV testing, all with different testing characteristics. Commonly used fourth-generation screening tests combine testing for HIV-specific antibodies and a p24 antigen test. While the confirmatory test of choice was the Western blot, many laboratories now are using the HIV Multispot ELISA for confirmation of infection.

The clinical manifestations of HIV infection vary widely from asymptomatic to the varied presentations of AIDS-defining conditions that are a result of profound immunosuppression.

Patients with acute HIV infection may present with signs and symptoms of the acute retroviral syndrome, a mononucleosis-like illness. They may have fever and lymphadenopathy and in some cases may have rash. Other symptoms, including mucocutaneous ulcers, sore throat, nausea, vomiting, diarrhea, and headache, may also be present.

Patients may present with a variety of other nonspecific symptoms or signs. Endocrine abnormalities may include hypogonadism, insulin resistance, and lipid abnormalities. Renal dysfunction, myocarditis, and pericarditis may be present. Oral disease may include thrush, oral hairy leukoplakia, and gingivitis. Patients may present with cutaneous infections due to herpes simplex virus, varicella-zoster virus, and molluscum contagiosum.

The most common dermatologic finding associated with HIV infection is seborrheic dermatitis, seen in 31% of otherwise asymptomatic patients with HIV and 83% of patients with AIDS, compared to only about 2% of the general population.

Patients may present with signs and symptoms of one of many AIDS-defining conditions, including multiple or recurrent bacterial infections, candidiasis, disseminated coccidioidomycosis, extrapulmonary cryptococcosis, chronic intestinal cryptosporidiosis, cytomegalovirus retinitis, chronic ulcers of herpes simplex, disseminated histoplasmosis, chronic intestinal isosporiasis, Kaposi sarcoma, Burkitt lymphoma, primary lymphoma of the brain, disseminated Mycobacterium avium complex or Mycobacterium kansasii infection, Mycobacterium tuberculosis infection, Pneumocystis jirovecii pneumonia, progressive multifocal leukoencephalopathy, recurrent Salmonella septicemia, or toxoplasmosis of the brain.

The most common conditions leading to evaluation and diagnosis with AIDS are P jirovecii pneumonia, HIV wasting syndrome, and esophageal candidiasis.

Associated malignancies of HIV include lung cancer, Kaposi sarcoma, Hodgkin lymphoma, non-Hodgkin lymphoma, cervical cancer, hepatocellular cancer, anal cancer, and mouth cancer (human papillomavirus [HPV] associated; see oral mucosal wart).

Related topics: HIV/AIDS-related pruritus, HIV-associated lung disease, papular pruritic eruption of HIV