Inclusion Criteria

Concurrent Medication:

Allowed:

• Patients who require anti-diarrheal medication must have received only one anti-diarrheal medication, loperamide, for at least 7 days prior to study entry. Dose of loperamide cannot be increased during study.
• Aerosolized pentamidine.
• Ganciclovir for cytomegalovirus (CMV) retinitis only but patient must be stable at least 4 weeks prior to study entry.
• Zidovudine (AZT).
• Nystatin for oropharyngeal infections if not taken within 2 hours of diclazuril.

Patients must have:

• Diagnosis of AIDS that is confirmed HIV positive by Western blot or AIDS defined diagnosis, or CDC defined AIDS. Stool specimens positive for cryptosporidium oocysts.
• Given written informed consent after the purpose and nature of the study, as well the possible drug-related adverse effects, have been explained.
• Ability to return for all subsequent applicable visits on days 8, 15, 21, and, if necessary, 28.

Prior Medication:

Allowed:

• Aerosolized pentamidine.
• Loperamide.
• Ganciclovir for cytomegalovirus (CMV) retinitis.

Exclusion Criteria

Co-existing Condition:

Patients with the following are excluded:

• Diagnosis of cryptosporidiosis less than 4 weeks prior to study entry, unless patient has been diagnosed with AIDS for more than 4 weeks.
• Other treatable enteric pathogens including Clostridia must be treated and eradicated prior to study entry.
• Inability to swallow capsules.
• Uncontrolled vomiting.

Concurrent Medication:

Excluded:

• Trimethoprim/sulfamethoxazole (Bactrim).
• Ganciclovir for any other reason except cytomegalovirus (CMV) retinitis.
• Other antibiotics.
• Other anti-protozoal drugs.
• Anti-fungal drugs other than nystatin.
• Amphotericin B.
• Other investigational drugs.

Patients with the following are excluded:

• Diagnosis of cryptosporidiosis less than 4 weeks prior to study entry, unless patient has been diagnosed with AIDS for more than 4 weeks.
• Inability to swallow capsules.
• Uncontrolled vomiting.
• Life expectancy of < 28 days.
• Can not be depended upon to follow the instructions of the investigator.
• Participation in an investigational study within 15 days of study entry.

Prior Medication:

Excluded within 15 days of study entry:

• Another investigational drug or device (except aerosolized pentamidine).

Prior Treatment:

Excluded within 15 days of study entry:

• Participation in an investigational study.