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