Acquired Immune Deficiency Syndrome

Risk: In general, risk factors for HIV/AIDS include unprotected homosexual or heterosexual sex, intravenous drug abuse with contaminated needles, exposure to infected body fluids (e.g., needlestick), and maternal-fetal transmission during pregnancy and childbirth.

Between 1998 and 2002, the incidence of HIV decreased in whites and Hispanics while increasing in Asians/Pacific Islanders, blacks, and Native Americans. In those with HIV infections that progressed to AIDS in 2001, 32% were white, 55% black, and 12% Hispanic. Asians/Pacific Islanders and Native Americans accounted for less than 1% during that period ("HIV/AIDS Surveillance Report").

Incidence and Prevalence: Through 2002, almost 400,000 people in the US were living with AIDS. Of those, 42% were black, 37% white, and 20% Hispanic, and less than 1% each were Native Americans or Asians/Pacific Islanders. The reported cases during the year 2002 alone numbered 32,513 cases in males and 11,279 cases in females ("HIV/AIDS Surveillance Report"). At the end of 2001, almost half of AIDS patients live in four states: New York (17%), California (14%), Florida (11%), and Texas (7%). Cities with a population of over 500,000 account for 83% of those currently living with AIDS. Close to 45% of AIDS patients contracted HIV through male homosexual contact, 27% from drug injection needles, and 20% through heterosexual activity ("HIV/AIDS Surveillance Report").

A recent report by UNAIDS found the following: Worldwide in 2003, about 38 million people globally were estimated to be living with HIV. The AIDS epidemic claimed nearly 3 million lives and close to 5 million people acquired HIV in 2003. Sub-Saharan Africa continues to have high incidence, with southern Africa most affected. Prevalence rates exceed 20% in the most southern countries. Uganda has dramatically reversed the trend by very active public health measures with prevalence now reduced to 4% from a rate of over 12% a decade ago. Asia is now home to some of the fastest growing AIDS epidemics in the world. In Asia, an estimated 7.4 million people (range: 5.0 to 10.5 million) are living with HIV. Incidence in Western Europe has stabilized in a similar manner to North America. However, the epidemics in Eastern Europe continue unabated. Estonia, Latvia, the Russian Federation, and Ukraine are the countries in this region most affected.

History: The symptoms of AIDS reflect a failed immune response, resulting in variable and nonspecific physical signs. Typically, the patient will present with a range of complaints. Those complaints might include short-term memory loss, difficulty concentrating, mood changes (usually depression, apathy, or suicidal ideation), altered mental status/dementia, cough and shortness of breath, night sweats, skin rashes or growths, easy bruising, unexpected nosebleeds, persistent fever, difficulty swallowing (dysphagia), vomiting, abdominal pain, headache, diarrhea, weight loss, chest pain, and visual changes, including blurred vision or spots that interfere with vision (floaters). The history may also relate to a specific disease that the immune-compromised individual has contracted, such as toxoplasmosis or tuberculosis.

Physical exam: Individuals with AIDS have symptoms of specific opportunistic infections or cancers. Those with full-blown AIDS may have a combination of skin (dermatologic), digestive (gastrointestinal), lung (pulmonary), brain and nerve (neurologic), eye (ophthalmologic), and/or muscle and bone (musculoskeletal) conditions. One type of growth (neoplasm) seen commonly in individuals with AIDS is Kaposi's sarcoma (KS). It appears as reddish-brown raised growths on the skin or in the mouth. Bleeding (hemorrhage) in the retina, yeast infections of the mouth (thrush) and vagina (candida), viral infections in the mouth, chronic herpes, and aggressive tooth or gum disease are also common. Weight loss and decreased physical vigor, appetite, and mental activity (wasting syndrome) may be present.

Tests: AIDS testing focuses initially upon verification of HIV infection, using blood or urine tests in a doctor's office or a home test.

Blood tests: HIV infection is determined by either direct detection of the virus itself or detection of the antibodies the individual produces in response to viral infection. Direct detection of the virus may be done following infection but may be negative early in infection. HIV polymerase chain reaction (PCR) or HIV culture tests are commonly used.

For antibody detection tests, there is a time delay before the immune system can mount a response against HIV; therefore, a 6-month waiting period following infection is usually recommended in order to increase the reliability of the test. Note that HIV-infected individuals with AIDS symptoms are usually infected with the virus much longer than 6 months, and HIV antibodies are almost always present in the bloodstream. The most common types of antibody tests for HIV diagnosis include the enzyme-linked immunoabsorbent assay (ELISA, with sensitivity and specificity more than 95% accurate), Western blot, immunofluorescence, radioimmune-precipitation, and hemagglutination.

Oral/Urine tests: The Food and Drug Administration (FDA) has approved one oral test. The Oral Fluid Vironostika HIV-1 MicroElisa System and the OraSure HIV-1 WB kit in combination with the OraSure Collection system are highly reliable in identifying HIV-infected individuals. A urine test approved by the FDA is the HIV-1 antibody ELISA. It has not been approved, however, as a stand-alone diagnostic test, and individuals with reactive urine specimens should be tested again using a blood test.

Home tests: The first FDA-approved at-home testing service, called Confide, was withdrawn from the market because of lack of consumer demand. Subsequently, the FDA approved the Home Access and Home Access Express tests, which are currently available. The individual is provided a specimen collection device in which a drop of the individual's blood is blotted onto a card. The specimen card is mailed to a central testing service, and the individual is informed anonymously of the results by telephone. Post-test counseling is also provided.

The rate of progression of HIV and AIDS is directly related to the rate of increase in the number of viral particles (viral load) in the bloodstream or tissue of an infected individual. Viral load measurement can therefore serve as both an accurate predictor of HIV-related disease progression and an indicator of the effects of antiviral drug treatment. Viral load can be determined by measuring HIV ribonucleic acid (RNA) in plasma. The three types of assays commonly used to measure HIV RNA are the reverse transcription polymerase chain reaction (RT-PCR), the branched deoxyribonucleic acid (bDNA) test, and the nucleic acid sequence-based amplification (NASBA) test.

Other tests may be performed to monitor the extent of damage done to the immune system by the virus. Most important is a count of the number of CD4+ T-lymphocytes in the bloodstream using flow cytometry analysis. This test is also useful in monitoring the effectiveness of antiretroviral drug therapy, determining the risk for opportunistic diseases and the need for preventative (prophylactic) drug administration, and assessing the prognosis for the individual with AIDS.

Other tests may include a complete blood count (CBC) with a white blood cell differential count, blood urea nitrogen (BUN), creatinine and electrolytes, a blood culture, arterial blood gases (ABG), liver function tests, glucose and lipid profiles, stool culture, lumbar puncture and CSF analysis, a rapid plasma reagin (RPR) test or a Venereal Disease Research Laboratory (VDRL) test for syphilis, a hepatitis B core antibody test, hepatitis C and toxoplasmosis serology, a purified protein derivative (PPD) test for tuberculosis, and a Pap smear in women. In some clinical settings, urinalysis, cytomegalovirus (CMV) serology, and a qualitative test for glucose-6-phosphate dehydrogenase (G6PD) may be advisable. A CT or MRI can be used to identify whether pneumonia or cancer is present.