Sources Of Contamination

Cryptosporidium can be acquired by ingestion of contaminated water and foods. The oocysts are already infectious when excreted; therefore, cryptos-poridiosis can also be transmitted via the fecal-oral route involving person-to-person or animal-to-person transmission. Recreational [15-18] and drinking waters [19,20] have been responsible for various cryptosporidium waterborne outbreaks. Chlorine concentrations suitable for drinking water have proven insufficient to inactivate cryptosporidium oocysts. Prepared foods and apple cider have also been described as sources for cryptosporidium contamination [21-24]. Inappropriate manipulations of foods by food handlers [25] or fruits contaminated with cattle feces have also been sources of cryptosporidium contamination. Zoonotic transmission has also been important, particularly for hikers who drink river or lake water without disinfecting it. Cryptospori-dium can infect a diverse variety of animals, particularly cattle. Zoonotic contaminations have been described in veterinary students and animal caretakers [26,27]. Outbreaks in day care centers have also been reported. Children are highly susceptible to infection, and transmission of this parasite can be high if proper hygiene practices are not in place, either at home or day care centers [28-33]. The same conditions are favorable for cryptosporidium outbreaks in hospitals [34, 35].

Investigations of cyclospora outbreaks suggest that it can be acquired when ingesting water [36-38] and food [39-44] that contain the parasite's oocysts. Cyclospora has been isolated from fresh produce in the U.S. and elsewhere [36,45,46], suggesting that foods play an important role in cyclos-pora transmission. The mechanisms and dynamics of transmission of cyclospora are more complicated than those of cryptosporidium since oocysts are not fully sporulated and therefore infective when passed from an infected human.

Contaminated water used for irrigation [47] or pesticide spraying support oocyst survival [48]. Aerosols, insects [49-51], and contaminated water courses and streams used in crop irrigation may factor in the introduction of viable oocysts into fresh produce.

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