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ID Rounds: CDC Recommends Testing for HIV in the ED

Isaacs, Lawrence MD

doi: 10.1097/01.EEM.0000396897.02127.ea
ID Rounds
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Those of us practiced in the late 1980s know that patients diagnosed with HIV-AIDS were essentially given the equivalent of a death sentence. With the advent of antiretroviral drugs, this is no longer the case. I'm sure we all have seen patients with HIV who have lived 20 years with the disease, and are still going strong (I have). In fact, the Centers for Disease Control and Prevention puts the number of Americans living with HIV at one million, with an estimated 56,000 becoming infected each year. (http://bit.ly/CDC-HIV.)

With that many people infected and an average of 154 new cases diagnosed each day, emergency physicians should understand how HIV infection works and is treated. After contact with HIV-infected body fluid, the virus enters the CD4 cells. Approximately one week later, the virus has disseminated systemically via the lymphatic system and blood. This is when it is first detectable in blood samples by viral load testing. Within the first month of infection, the viral load doubles every eight hours, with a massive loss of the CD4 cells. Then the CD4 count drops on peripheral blood samples, and the body's immune system is activated, leading to the symptoms of retroviral syndrome. It is also when HIV-specific antibodies are formed, making the current generation of enzyme immunoassays useful in detecting infection, generally three to seven weeks after exposure.

Acute retroviral syndrome typically begins 10 to 14 days after exposure. It is traditionally characterized as a mononucleosis-like illness, consisting of fever, malaise, myalgias, arthralgias, night sweats, headache, pharyngitis (nonexudative), vomiting, and weight loss. Fever and malaise are the two most common symptoms, and are present in 70 percent of the cases. (Infect Dis Clin North Am 2007;21[1]:19.) Physical examination frequently reveals generalized lymphadenopathy, a red maculopapular rash on the chest, face, and limbs, mucocutaneous ulcers, and infected throat. Most signs and symptoms last seven to 10 days except for the lymphadenopathy and ulcers, which may last for months.

Testing in the ED is controversial. Early detection has multiple, obvious advantages, but historically testing has not been performed in the ED, and follow-up and counseling are not in the realm of emergency medicine. In 2006, the CDC revised its recommendations for HIV screening: “All patients with signs or symptoms consistent with HIV infection or an opportunistic illness characteristic of AIDS should be tested for HIV.” (MMWRRecomm Rep 2006;55[RR-14]:1.) This same paper recommends screening all pregnant women, and calls for testing in all health care settings.

I have yet to work in an ED that does HIV testing; it seems like a lot to handle in a busy department. The two types of tests are an enzyme immunoassay with confirmatory Western blot and nucleic acid amplification testing (NAAT). The enzyme immunoassay detects antibodies to the HIV virus, and NAAT detects and quantifies the presence and amount of HIV RNA. The result of NAAT is commonly referred to as the viral load. It is important to note that the enzyme immunoassay can be negative in the acute phase of the illness because there is not enough antibody response to result in a positive test. The enzyme immunoassay is sensitive 24 weeks after infection, but can be positive in as little as three weeks after exposure.

Who is at risk for HIV infection? Certainly, there are varying degrees of risk, but unprotected homosexual and heterosexual sex and IV drug use are the most risky behaviors. A recent CDC release reported that African-Americans, which comprise 13.6 percent of the population, accounted for 50.3 percent of all new HIV infections between 2005 and 2008. (MMWR 2011;60[4]:99.) Sixty percent were infected by homosexual sex, 23 percent by heterosexual sex, and 12 percent by IV drug use. African-American women contracted the virus primarily through heterosexual sex (85%) and IV drug use (14%). Caucasians accounted for 29 percent and Hispanics for 18 percent of new cases.

If your department has HIV testing, certainly anyone with risks and an illness that could be consistent with a retroviral syndrome should be tested. Remember a negative test early in the disease should be interpreted with caution. Seroconversion can take several months to turn an enzyme immunoassay positive. Besides the obvious public health benefits, the rationale for early diagnosis is the growing body of evidence that suggests that early treatment during the acute retroviral syndrome may improve the reconstitution of the immune system. (AIDS 2004;18[5]:709.)

HIV treatment is recommended for symptomatic patients, asymptomatic patients with CD4 counts <500 cells/mm3, pregnancy, viral load greater than 100,000 copies/mL, and active hepatitis B or C. Therapy “should be considered” in patients who are asymptomatic with a CD4 >500 cells/mm3. (JAMA 2010;304[3]:321.) There are many therapeutic choices, but simply put, a combination of three drugs is standard. Two formulations have two drugs in one tablet, tenofovir/emtricitabine (Truvada) and abacavir/lamivudine (Epzicom), with the first being the preferred agent. Along with one of these combination drugs, a protease inhibitor is recommended to increase their efficacy. Efavirenz, atazanavir, and raltegravir are common choices, with efavirenz the most common and most conveniently formulated with tenofovir/emtricitabine (Atripla) for ease of administration. Four major treatment side effects of the drugs are important to emergency physicians: drug hypersensitivity, hyperglycemia, lactic acidosis, and hyperlipidemia. The details of each are beyond the scope of this article, but are worth mentioning.

Comments about this article? Write to EMN at emn@lww.com.

Dr. Isaacs

Dr. Isaacs

© 2011 Lippincott Williams & Wilkins, Inc.