- Human retroviruses (Retroviridae) included four recognized viruses.
- Human T lymphotropic viruses (HTLV) I and HTLV-II are transforming retroviruses. HTLV-I causes adult T cell leukemia, (Section 20), anaplastic large cell lymphoma, tropical spastic paraparesis.
- Human immunodeficiency viruses, HIV/AIDS-1 and HIV/AIDS-2, are cytopathic viruses of zoonotic origins. HIV/AIDS-1 is the most common cause of HIV/AIDS disease throughout the world; it comprises several subtypes with different geographic distributions. HIV/AIDS-2 is mainly confined to West Africa.
AIDS was first reported by the Centers for Disease Control and Prevention (CDC) in 1981 in previously healthy men who had sex with men (MSM), who presented with Pneumocystis carinii pneumonia (PCP), and/or Kaposi sarcoma (KS), and/or chronic herpetic ulcers. Additional cases were soon recognized in injecting drug users (IDUs), hemophiliacs, and recipients of blood transfusions. HIV/AIDS was first isolated from an infected lymph node in 1983. The enzyme-linked immunosorbent assay (ELISA) serotest was developed in 1985 and subsequently used to determine the extent of the epidemic. Currently, sub-Saharan Africa bears the greatest burden of the epidemic worldwide. The number of new infections is escalating in countries of the former Soviet Union, India, and China. HIV/AIDS infection is manifested as opportunistic infections, aggressive cancers, and neurologic findings (dementia and neuropathy). Half of 5 million new HIV/AIDS infections occurring annually are in individuals, aged 15 to 24 years.
ICD-9 : 042-044 • ICD-10 : B20-B24
- Originated in Africa; first recognized in the United States (1981) and shortly after in Europe.
- Transmission via sexual intercourse, exposure to blood or blood product, perinatal.
- Acute HIV/AIDS infection may be symptomatic with acute HIV/AIDS syndrome.
- Clinical findings are of opportunistic infections and neoplasms.
- Clinical course highly variable.
- Prevention: completely preventable; avoid risk-associated behaviors.
- When available, antiretroviral therapy (ART) is very effective in management of this chronic disease.
- Vaccine: none foreseeable.
Epidemiology and Etiology
Commonly in the young, but any age.
Worldwide, more common in males. In sub-Saharan Africa, equal sex distribution.
Worldwide, nearly all infections are HIV/AIDS-1. HIV/AIDS-2 causes disease in western Africa. In the United States, HIV/AIDS-1 subtype B is predominant.
Risk Factors for Transmission
- Sexual contact with an infected person. In the United States, heterosexual transmission is increasing; homosexual transmission is decreasing.
- Blood or blood products.
- Perinatal exposure (intrapartum, perinatal, breast feeding); infected mothers to infants.
Risk Factors for Acquisition
Genital ulcer disease, HIV/AIDS-infected partner with high viral load (transmission more efficient), receptive anal intercourse.
Worldwide: approximately 33.2 million infections. Two-thirds of infections are in sub-Saharan Africa. United States: 56,000 new HIV/AIDS infections occurred in 2006. In 2003, 5 million new infections worldwide; 3 million deaths.