Inclusion Criteria

Patients must have:

• Documented HIV infection.
• Intestinal cryptosporidiosis.
• Willingness to undergo a 1 week washout phase of all anticryptosporidial medications and stabilization on a protocol directed, antidiarrheal regimen.
• Greater than or equal to 4 stools per day, on average, for a minimum of 21 out of 28 days prior to study entry, secondary to cryptosporidiosis.

AS PER AMENDMENT 2/10/97:

• Four or more stools per day, on average, during the 5-day screening period prior to baseline.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms and conditions are excluded:

• Inability to tolerate oral medications.
• Life expectancy less than 3 months in the opinion of the investigator.
• Active CMV colitis, C. difficile colitis, giardiasis, salmonellosis, shigellosis, campylobacteriosis, inflammatory bowel disease, diarrhea secondary to another documented intestinal pathogen, or active or uncontrolled MAC disease, defined as symptomatic MAC disease and/or a patient who is not on appropriate anti-MAC therapy in the presence of MAC disease.

NOTE:

• Patients who have been treated for MAC disease for at least 4 weeks and have resolved their symptoms may be enrolled. Patients dually infected with microsporidiosis may be randomized to the study but will not count toward the sample size.

AS PER AMENDMENT 2/10/97:

• Failure to record a minimum of four days of information on the use of antidiarrheal medication and the frequency of bowel movements in the daily diary during the screening period.
• Allergy to corn or corn products.

Concurrent Medication:

Excluded:

• Need for continuing use of any medications with putative anticryptosporidial activity, including paromomycin, azithromycin, clarithromycin, spiramycin, bovine colostrum, monoclonal anticryptosporidial antibody preparations, letrazuril, atovaquone, diclazuril, octreotide and albendazole (prohibited during the acute treatment phase for patients dually infected with microsporidiosis)..

NOTE:

• Patients who develop cryptosporidiosis while taking azithromycin or clarithromycin may be enrolled as long as they have been taking those medications for at least four weeks and remain on a stable dosage.
• All antidiarrheals that are not part of the protocol directed Antidiarrheal Stabilization Regimen.
• The addition of any new antiretroviral agent or immunomodulator therapy the first 63 days on the study.

Prior Medication:

Excluded:

• Treatment at any time prior with nitazoxanide.
• Addition of any new antiretroviral or increase in the dosage or current antiretrovirals within 4 weeks to study entry.