Human Immunodeficiency Virus (HIV, AIDS) (cont.)
What about treating non-HIV-infected people exposed to the blood or genital secretions of an
HIV-infected person?
Recently, a great deal of interest has focused on preventing transmission to uninfected people
who are inadvertently exposed by the early administration of antiviral therapy. Because the risk of infection after most isolated exposures is relatively small and the number of patients needed for study would be great, formal studies are difficult to perform. Animal studies and some human experience, however, suggest that post-exposure treatment may be effective. In fact, the current recommendation is that health-care workers who experience a needle stick from an infected person take antiviral medication for
four weeks in order to reduce the risk of infection. Guidelines now recommend similar preventive treatment for people with sexual exposures to HIV. Those individuals considering this type of preventative treatment, however, must be aware that post-exposure treatment cannot be relied upon to prevent HIV infection. Moreover, such treatment is not always available at the time most needed and is probably best restricted to unusual and unexpected exposures, such as a broken condom during intercourse. Although regimens with
two or three drugs generally are recommended for those exposed in the health-care setting, the best therapy for sexual exposure still is unknown and ideally should be initiated within hours of exposure and certainly within the first several days. Updated guidelines are published and available at
http://www.hivatis.org.
What can be done for people who have severe immunosuppression?
Although one goal of antiviral therapy is to prevent the
development of immune suppression, some individuals are already immunosuppressed
when they first seek medical care. In addition, others may progress to that
stage as a result of resistance to antiviral drugs. Nevertheless, every effort
must be made to optimize antiviral therapy in these patients. In addition,
certain specific antibiotics should be initiated, depending on the number of CD4
cells, to prevent the complications (that is, the opportunistic infections) that
are associated with HIV immunosuppression. Guidelines for the prevention of
opportunistic infections can be found at http://www.hivatis.org.
In summary, patients with a CD4 cell count of less than 200 should receive preventative treatment against
Pneumocystis jiroveci with trimethoprim/sulfamethoxazole (Bactrim, Septra), given once daily or three times weekly. If they are intolerant to that drug, patients can be treated with an alternative drug such as dapsone or atovaquone (Mepron). Those patients with a CD4 cell count of less than 100 cells per mm3 who also have evidence of past infection with
Toxoplasma gondii, which is usually determined by the presence of toxoplasma antibodies in the blood, should receive trimethoprim/sulfamethoxazole. Toxoplasmosis is an opportunistic parasitic disease that affects the brain and liver. If a person is using dapsone to prevent
Pneumocystis jiroveci, pyrimethamine and leucovorin can be added once a week to dapsone to prevent toxoplasmosis. Finally, patients with a CD4 cell count of less than 50 cells per mm3 should receive preventive treatment for
Mycobacterium avium complex (MAC) infection with weekly azithromycin (Zithromax), or as an alternative, twice daily clarithromycin (Biaxin) or rifabutin (Mycobutin). MAC is an opportunistic bacterium that causes infection throughout the body.
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