Cryptosporidiosis is a common causes of diarrhea in people and livestock. Cryptosporidiosis is caused by coccidial parasites of the genus Cryptosporidium. Transmission occurs through the ingestion of infectious oocysts in contaminated water or food and by direct contact with fecal material from individuals or animals actively shedding oocysts (1). Oocysts shed in feces are fully sporulated and immediately infective (2). This has critical ramifications in the development of control strategies for Cryptosporidiosis. In the case of Eimeria and Isospora sp., common coccidial pathogens of livestock, sporulation of oocysts occurs in the environment, rather than within the intestinal lumen of the host (2). Consequently, the oocysts contained in the fecal material shed by an Eimeria or Isospora sp. infected host poses minimal risk unless the fecal material remains in contact with new hosts for the obligatory period of sporulation. As a direct consequence, frequent removal of feces or movement to clean sites will halt transmission of these pathogens, unlike for cryptosporidia. Cryptosporidiosis most commonly affects neonatal calves. However, infections have been reported in sheep, goats, horses, swine, camels, deer, raccoons, dogs, cats and birds (3). Regardless of the species affected, young animals are at greater risk for either infection or disease. The primary clinical sign in calves is a profuse watery diarrhea. Over 90% of dairy farms and 40% of beef farms are endemically infected with Cryptosporidiosis (4). Approximately half of dairy calves between the ages of 1 and 3 weeks of age are actively shedding oocysts at any time (5,6,7). Cryptosporidiosis also is one of the most common causes of infectious diarrhea in humans (8). Although clinical manifestations of Cryptosporidiosis vary with age and immune status, they include voluminous, self-limiting diarrhea of 1-14 days duration, often accompanied by abdominal cramps, fatigue, vomiting, fever and malaise. The prevalence and incidence of Cryptosporidiosis is higher in people infected with HIV (9-17) and in residents of developing countries whereas in developed countries it is sporadic with large scale outbreaks associated with contaminated water and food sources, recreational exposures to contaminated waters, and horizontal transmission in child care settings. In immunodeficient humans, Cryptosporidiosis can cause a chronic, life- threatening diarrhea (18) with case fatality rates of approximately 50% (19). No drug or drug combination effectivelytreats Cryptosporidiosis in humans.
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