Human Immunodeficiency Virus Infection

Incidence and Prevalence: Since the beginning of the epidemic in the early 1980s, almost 70 million people in the world have been infected with the HIV virus. About 35 million people have died of AIDS. Worldwide, 35.3 million people were living with HIV at the end of 2012 (WHO). The Centers for Disease Control and Prevention estimates that 1,148,200 persons aged 13 years and older are living with HIV infection in the U.S, including 207,600 (18.1%) who are unaware of their infection (HIV Surveillance report).

The estimated incidence of HIV infection in the US has remained stable overall in recent years, at about 50,000 new HIV infections per year. However, some groups are affected more than others. Men who have sex with men (MSM) continue to bear the greatest burden of HIV infection, and among races/ethnicities, blacks continue to be disproportionately affected (HIV Surveillance Reports).

History: An HIV-infected individual may report high-risk sexual behavior, intravenous drug use, or rarely, multiple transfusions of blood or blood products. Two to four weeks after the initial infection, individuals will experience a brief flu-like illness with a sore throat, weakness, fever, or rash. These symptoms will disappear within a few days or weeks and are followed by a long incubation (latency) period, during which there are no overt signs of infection. After this latency period, HIV-infected individuals most often progress to AIDS, reporting altered mental status that includes short-term memory loss, concentration difficulties, mood changes (usually toward depression, apathy, or suicidal ideation) or dementia; symptoms may also include cough, shortness of breath, night sweats, skin growths, easy bruising, unexpected nosebleeds, difficulty swallowing (dysphagia), chest pain, persistent fever, diarrhea, abdominal pain, vomiting, headaches, and/or weight loss.

Physical exam: The HIV-infected individual may have a fever, skin rash, and/or enlarged lymph nodes that show up 2 to 4 weeks after initial infection. This is followed by a latent phase that can last up to 10 years or more. During this phase, there are no clear physical signs, except for occasional nonthreatening infections such as chronic herpes (shingles) or oral fungal infection with Candida (thrush). HIV-infected individuals who have developed AIDS may have one or several AIDS-defining illnesses such as lesions in the digestive or respiratory tract that are characteristic of yeast infections (candidiasis), plaque-like lesions in the mouth (oral hairy leukoplakia), or raised blue or purple spots anywhere on the body (Kaposi's sarcoma). An eye examination may reveal blurry vision, spots before the eyes (floaters), or loss of vision. It may be difficult to visualize the retina during an eye examination, and the retina may have a "cottage cheese and ketchup" appearance. Wheezes or crackling (dry rales) sounds in the lungs, enlarged nodes, abdominal masses, fluid in the abdominal cavity (ascites), enlarged liver (hepatomegaly), enlarged spleen (splenomegaly), reflex abnormalities, gait problems, and cranial nerve impairment may also be noted during physical examination.

Tests: HIV infection can be determined by blood or urine tests or by home testing.

Blood tests: HIV infection can be determined by either direct detection of the virus or detection of the antibodies that the individual produces in response to HIV. Direct detection of the virus may be done at any time following infection, and the HIV polymerase chain reaction (PCR) or HIV culture tests are commonly used. However, with antibody detection tests, there is a time delay before the immune system will mount a response against HIV, and a waiting period of 6 months following infection is usually recommended to increase reliability. The most common types of antibody tests for HIV diagnosis include the enzyme-linked immunoabsorbent assay (ELISA), Western blot, immunofluorescence, radioimmune-precipitation, and hemagglutination.

Oral/Urine tests: Oral tests use oral fluid (not saliva) that is collected from the mouth using a special collection device. This is an enzyme immunoassay (EIA) antibody test similar to the standard blood EIA test. These tests require a follow-up confirmatory Western Blot using the same oral fluid sample.

The accuracy of urine tests is less than the accuracy of blood and oral fluid tests. These tests require a follow-up confirmatory Western Blot using the same urine sample.

Home tests: Home HIV tests are available over-the-counter at local drug stores. The individual collects a sample, run the test, and obtain their test results at home.

The rate of HIV disease progression is measured by the rate of increase in viral load in the bloodstream or tissue of an infected individual. Thus, repeated viral load measurement can serve as both an accurate indicator of disease progression and an indicator of the effectiveness of anti-viral drug treatment. Viral load can be determined by measuring HIV ribonucleic acid (RNA) in plasma. Commonly, three types of assays are used to measure HIV RNA: reverse transcriptase polymerase chain reaction (RT-PCR), the branched deoxyribonucleic acid (bDNA) test, or the nucleic acid sequence-based amplification (NASBA).

Other tests may be performed to monitor the extent of damage the virus has done to the immune system. The most important of these counts the number of CD4+ T lymphocytes in the bloodstream using flow cytometry. This test is also used to monitor the effectiveness of antiretroviral drug therapy, to determine the risk for opportunistic diseases and the need for preventative (prophylactic) drug administration, and to assess the prognosis for the HIV-infected individual.

Other tests may include a complete blood count (CBC) with a white blood cell differential count, blood urea nitrogen (BUN) and creatinine, liver function tests, glucose and lipid profiles, arterial blood gases (ABGs), blood chemistries, electrolytes, blood culture, stool culture, 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. Additional diagnostic tests include chest x-ray, head computed tomography (CT) scan, cerebrospinal fluid analysis, and lumbar puncture.

Risk: In an immune compromised individual, working with heavy public contact, indigent or incarcerated populations, or in health care settings may place the individual at increased risk of further or recurrent infection. Some risk can be mitigated by frequent hand washing, gloves, or masks. Universal blood and body fluid precautions must be exercised in both directions to protect the individual and those he or she comes into contact with. Occupations with high risk of cuts in close proximity to other workers should be examined for safety precautions.

Capacity: In the short term, once stabilized and treated, there would not be expected to be any change in an individual’s capacity limits. However, HIV stage 3 is a progressive disease and long term fatigue, anemia, recurrent infections and pulmonary limits may reduce capacity. Testing with stress ECHO and Pulmonary Function would be useful.

Tolerance: Fatigue is a prominent symptom of untreated HIV infection as well as the accompanying opportunistic infections. Once infection is stabilized, and CD4+ T lymphocytes counts are restored to normal, most patients can return to work and will function well. Limits may be due to perceived worksite acceptance. Counseling may be of great use in newly diagnosed individuals to assist in return to work transition.