- Clinically significant active or acute (onset within the month previous to study entry) medical problems, including the following: opportunistic infections, e.g., active cryptococcosis, Pneumocystis carinii pneumonia, herpes zoster, histoplasmosis, or cytomegalovirus; nonopportunistic diseases, including but not limited to the following: progressive multifocal leukoencephalopathy, lymphoma, or malignancy requiring systemic therapy