Background:

Clinically apparent human immunodeficiency virus (HIV) infection first was recognized in 1981 in homosexual men in New York City who presented with evidence of a profound acquired immune deficiency syndrome (AIDS). We now appreciate that HIV infection is a worldwide health problem that affects millions of men and women. HIV has the capability to affect every organ system in the body by direct damage by the virus or by rendering the host susceptible to opportunistic infections. This article discusses some of the more common HIV-related illnesses that are seen frequently in the ED.

Pathophysiology:

HIV is a Lentivirus, a subgroup of retroviruses. This family of viruses is known for latency, persistent viremia, infection of the nervous system, and weak host immune responses. HIV has high affinity for CD4 T lymphocytes and monocytes. HIV binds to CD4 cells and becomes internalized. The virus replicates itself by generating a DNA copy by reverse transcriptase. Viral DNA becomes incorporated into the host DNA, enabling further replication.

HIV is transmitted primarily through sexual contact (over 70%); worldwide, it is more common in heterosexual men and women than in homosexual men. Although the majority of initial HIV-related AIDS cases in the United States were homosexual men, more recently the majority of new cases of HIV infection are in the heterosexual population. Parenteral transmission occurs largely among intravenous drug users; transmission by contaminated blood products is rare in the United States, though this remains a serious problem in developing countries. Since the introduction of universal precaution practices, infection of health care workers through parenteral exposure remains rare. Children are infected primarily by perinatal transmission.

Frequency:

* In the US: More than 887,000 persons have AIDS, and an estimated 1-2 million persons have asymptomatic HIV infection.

* Internationally: Since the AIDS epidemic began, more than 20 million deaths have been attributed to AIDS. The current estimate of worldwide disease prevalence is more than 38 million HIV infections. Ninety-five percent of these cases are in developing countries, generally in sub-Saharan Africa and Southeast Asia.

Mortality/Morbidity:

The course of HIV infection is characterized primarily by latency. Unfortunately, profound immune suppression eventually develops and the illness appears to be almost uniformly lethal. More than 500,000 persons have died of AIDS in the United States.

Progression from HIV infection to AIDS occurs at a median of 11 years after infection. In the recent past, most patients would not survive more than 1-2 years following diagnosis of AIDS. However, since the introduction of highly active antiretroviral therapy (HAART) and prophylaxis against opportunistic pathogens, death rates from AIDS have begun to decline significantly.

Race:

In the United States, the breakdown of HIV infections by race is as follows:

* Whites - 41% of all cases

* African Americans - 39%

* Hispanics - 18%

Sex:

Most HIV infections still occur in men; however, the frequency of infection in women is increasing, especially in developing countries. In the United States, fewer than 18% of all HIV cases are in women, whereas worldwide an estimated 50% of all HIV patients are women.

Age:

Most AIDS cases occur in adults aged 25-44 years. Children represent fewer than 1% of AIDS cases in the United States. Internationally, children younger than 15 years are estimated to account for close to 10% of all HIV cases.

Reference:

excerpted from eMedicine.com. HIV Infection and AIDS. Jeff Dubin, MD, Medical Director, Emergency Department, Washington Hospital Center, Assistant Professor, Department of Emergency Medicine, Georgetown University School of Medicine.