Opportunistic infections have been a major source of morbidity and mortality among HIV-infected individuals since the beginning of the epidemic. Many deaths have been prevented by the effective prophylactic medications given to those patients whose CD4+ T-lymphocytes have fallen below 200 cells/ul. Both primary prevention, given to those who have never had the particular infection in question, and secondary prevention, given to those who actually acquired the infection to prevent relapse/recurrence, have been highly effective in maintaining wellness.
What about the new T-cells generated by highly active antiretroviral therapy (HAART)? Are these cells as effective as one’s original repertoire of lymphocytes in protecting against opportunistic infections? Increasing clinical data suggest that, indeed, these T-cells do work, and are effective in the prevention of these infections. Randomized trials, case-cohort trials, and observational data do support discontinuation of certain prophylactic medications, based on the extent and duration of CD4 response. Newer guidelines rely less on viral load criteria, though complete suppression predicts a more durable CD4+ response.
For some infections the recommended discontinuation CD4+ T-lymphocyte count is higher than that for initiation of prophylaxis, and in others it is the same. For Pneumocystis carinii, a sustained CD4+ T-lymphocyte count > 200 cells/ul for 3 or more months is considered to be sufficient to discontinue prophylaxis, with reinstitution of prophylaxis if the CD4+ count falls back below the 200 cells/ul threshold. For Mycobacterium avium-complex (MAC), initial prophylaxis should be initiated at 50 cells/ul, yet prophylaxis should not be discontinued until the CD4+ count is sustained over 100 cells/ul for 3 or more months.
The presentation will review both the primary and secondary prophylaxis guidelines and discontinuation recommendations for many of the HIV-related opportunistic infections for both adults and children.
Kirk O et al. Ann Intern Med 2002;137:239-50.
MMWR “Guidelines for Preventing Opportunistic Infections Among HIV-Infected Persons,” 2002;51(RR-8)1-53.