Patients with toxoplasmosis are given azithromycin at doses starting at the lowest dose for the first cohort, an intermediate dose for the second cohort, and a higher dose for the third cohort. Subsequent cohorts may receive azithromycin in increased dosage, if needed to determine the MTD. All patients also receive pyrimethamine. Folinic acid is also provided for as long as patients receive pyrimethamine. Patients are evaluated for clinical response to treatment at days 3, 7, and 14, and weekly for 6 weeks. Maintenance treatment with azithromycin continues for an additional 24 weeks. Patients who complete the study period without relapse or significant toxicity are offered continued therapy by the drug company and are followed for survival and relapse on a monthly basis for 1 year. After the MTD is determined, a subsequent cohort may be added for special studies.