Description

HIV is a retrovirus that integrates into CD4 T lymphocytes (a critical component of cell-mediated immunity), causing cell death and resulting in severe immunodeficiency, opportunistic infections, and malignancies:

• Because of treatment advances, HIV is now a chronic disease.
• The natural history of untreated HIV infection includes viral transmission, acute retroviral syndrome, recovery and seroconversion, asymptomatic chronic HIV infection, and symptomatic HIV infection or AIDS.
• Without antiretroviral treatment, the average patient develops AIDS ~10 years after transmission.
• All HIV-infected persons with CD4 <200 cells/mm³ or having AIDS-defining illnesses are categorized as having AIDS.

Epidemiology

• At the end of 2008, 33.4 million people were estimated to be living with HIV/AIDS worldwide per UNAIDS and the World Health Organization. Yearly, 2.7 million new HIV infections and 2 million deaths are attributable to AIDS
• US: 47,129 new cases in 2010; estimated 17,774 deaths of persons with AIDS in 2009. 619,400 Americans have died from AIDS since beginning of epidemic (1,2)

• Estimated 1.2 million persons in the US are living with HIV/AIDS; 20% unaware of their status (2)
• HIV/AIDS cases are disproportionately high among racial/ethnic minority populations
• Transmission of a drug-resistant virus rising
• Younger females particularly vulnerable

Risk Factors

• Sexual activity (70% of world transmission): Viral load strongest predictor of heterosexual transmission with ulcerative urogenital lesions (3)[B].
• Male-to-male sexual contact accounted for 61% of newly diagnosed HIV/AIDS cases in 2009.
• Injection drug use
• Children of HIV-infected women:
  • Maternal HIV-1 RNA level is the best predictor of transmission risk.
  • HIV testing and use of antiretroviral drugs in pregnant women and their newborns has reduced the incidence of perinatal HIV transmission by >70% (from 25–29% without treatment to 8% with treatment) (4)[B].
  • Pregnant women should be treated until viral load is undetectable.
  • Can be transmitted through breast-feeding
• Recipients of blood products between 1975 and March 1985
• Occupational exposure

Genetics
People who lack CCR5, a cell-surface chemokine coreceptor used by HIV to infect cells, are highly resistant to HIV infection

General Prevention

Avoid unprotected sexual intercourse and injection drug abuse.

Etiology

HIV, a retrovirus

Commonly Associated Conditions

• Syphilis may be more aggressive if HIV-infected
• Tuberculosis (TB) is coepidemic with HIV; test all persons with HIV for TB. Dually infected patients: 100× greater risk of developing active TB disease (compared with non-HIV) and higher rates of multidrug-resistant TB
• Patients coinfected with hepatitis C have a more rapid progression to cirrhosis.