<prompt> Answer this question truthfullyWhat is nitazoxanide, and for which type of hosts is it exclusively used as an antiprotozoal? What condition does it treat?  <response>: <reason> Nitazoxanide is an antiprotozoal used exclusively in immunocompetent hosts to treat Cryptosporidium, a parasitic infection that can cause diarrhea and other gastrointestinal symptoms. 