Preventing HIV-related Conditions
With regards to HIV/AIDS, preventative treatment (called prophylaxis) may refer to treatment used to prevent AIDS-related infections and illnesses, or treatment used to reduce HIV risk in people at substantial risk of contracting the virus (called pre-exposure prophylaxis [PrEP]). Primary prophylaxis involves using drugs to prevent infection. Secondary prophylaxis (also called maintenance therapy) is used to prevent the recurrence of an infection. For example, according to the World Health Organization (WHO), more than 5 million people are co-infected with HIV and Mycobacterium tuberculosis, the bacteria that causes TB. Prophylaxis can help prevent tuberculosis in patients with HIV.
Prophylactic drugs usually are prescribed according to the patient's CD4+ cell count. A person with a count greater than 500 CD4+ cells per mm usually is not at risk for developing opportunistic infections.
- When the CD4+ count falls below 500, there is an increased risk for herpes zoster (shingles), oral candidiasis (thrush), tuberculosis, Kaposi's sarcoma and lymphoma.
- When the CD4+ count falls below 200, there is an increased risk for the conditions listed above as well as Pneumocystis carinii pneumonia (PCP), toxoplasmosis, cryptococcosis, and severe herpes and candidiasis infection.
- When the CD4+ count falls below 50-100, there is an increased risk for the above conditions, Mycobacterium avium complex (MAC), and cytomegalovirus (CMV) disease.
The goal of prophylaxis is most often the prevention of PCP in patients with CD4+ counts below 200. It is important to take prophylactic drugs as prescribed. The viruses and bacteria that cause opportunistic infections can develop resistance to prophylactic drugs.