The goal of this clinical trial is to learn if nitazoxanide (NTZ) can treat Cryptosporidium infection in children age 6-12 months. The main questions it aims to answer are:

• Does NTZ treatment of diarrheal Cryptosporidium infection lower the number of days of diarrhea?
• Does NTZ treatment of diarrheal and non-diarrheal Cryptosporidium infection lower the number of days that parasites can be found in the stool?

Researchers will compare NTZ to a placebo (a look-alike substance that contains no drug) to see if NTZ works to treat Cryptosporidium.

Participants will:

• Take NTZ or placebo for 3 days
• Receive regular visits from field research assistants
• Provide blood and urine samples

Inclusion Criteria:

• tests positive for Cryptosporidium by stool point-of-care test, with or without active diarrhea
• family plans on remaining in the area for next 6 months

Exclusion Criteria:

• history of hypersensitivity to nitazoxanide.
• taking warfarin. Tizoxanide, the metabolite of nitazoxanide is highly bound to plasma proteins and may compete with binding sites of other highly plasma bound drugs with narrow therapeutic indices, including warfarin.
• history of renal insufficiency or a baseline serum creatinine = 40 µmol/L. Renal clearance of the drug has not been studied.
• history of hepatic dysfunction or serum aspartate aminotransferase (AST) ;
• 50 U/L, serum alanine transaminase (ATL) ;
• 50 U/L, or serum bilirubin ;
• 23 µmol/L. Hepatic clearance of the drug has not been studied.