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HIV-2 testing also is indicated for continued...

Among all HIV-infected people, the prevalence of HIV-2 is very low compared with HIV-1. However, the potential risk for HIV-2 infection in some populations (such as those listed) may justify routine HIV-2 testing for all people for whom HIV-1 testing is warranted. The decision to implement routine HIV-2 testing requires consideration of the number of HIV-2-infected persons whose infection would remain undiagnosed without routine HIV-2 testing compared with the problems and costs associated with the implementation of HIV-2 testing.

The development of antibodies is similar in HIV-1 and HIV-2. Antibodies generally become detectable within 3 months of infection. Testing for HIV-2 antibodies is available through private physicians or state and local health departments.

Are blood donors tested for HIV-2?

Since 1992, all U.S. blood donations have been tested with a combination HIV-1/HIV-2 enzyme immunoassay test kit that is sensitive to antibodies to both viruses. This testing has demonstrated that HIV-2 infection in blood donors is extremely rare. All donations detected with either HIV-1 or HIV-2 are excluded from any clinical use, and donors are deferred from further donations.

Is the clinical treatment of HIV-2 different from that of HIV-1?

Little is known about the best approach to the clinical treatment and care of patients infected with HIV-2. Given the slower development of immunodeficiency and the limited clinical experience with HIV-2, it is unclear whether antiretroviral therapy significantly slows progression. Not all of the drugs used to treat HIV-1 infection are as effective against HIV-2. In vitro (laboratory) studies suggest that nucleoside analogs are active against HIV-2, though not as active as against HIV-1. Protease inhibitors should be active against HIV-2. However, non-nucleoside reverse transcriptase inhibitors (NNRTIs) are not active against HIV-2. Whether any potential benefits would outweigh the possible adverse effects of treatment is unknown.

Monitoring the treatment response of patients infected with HIV-2 is more difficult than monitoring people infected with HIV-1. No FDA-licensed HIV-2 viral load assay is available yet. Viral load assays used for HIV-1 are not reliable for monitoring HIV-2. Response to treatment for HIV-2 infection may be monitored by following CD4+ T-cell counts and other indicators of immune system deterioration, such as weight loss, oral candidiasis, unexplained fever, and the appearance of a new AIDS-defining illness. More research and clinical experience is needed to determine the most effective treatment for HIV-2.

The optimal timing for antiretroviral therapy (i.e., soon after infection, when symptoms appear, or when CD4+ T cell counts fall below a certain level) remains under review by clinical experts. Guidelines for the Use of Antiretroviral Agents in HIV-Infected Adults and Adolescents, by the Department of Health and Human Services Panel on Clinical Practices for Treatment of HIV Infection, may be helpful to the clinician who is caring for a patient infected with HIV-2; however, the recommendations on viral load monitoring and the use of NNRTIs would not apply to patients with HIV-2 infection. Copies of the guidelines are available from the CDC National Prevention Information Network (1 800 458-5231) and from its Web site (www.cdcnpin.org). The guidelines also are available from the HIV/AIDS Treatment Information Service (1 800 448-0440; Fax 301 519-6616; TTY 1 800 243-7012) and on the ATIS Web site (www.hivatis.org).

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