Environmental Aspects of Cryptosporidium

Cryptosporidium, formerly classified to subclass Coccidia has been relocated to genus Gregarina which includes free living stages, enabling host-free multiplication and therefore may constitute an additional risk factor for human infection. The free stage of this parasitic protozoon, the oocyst, is incredibly durable under various environmental conditions, elucidating its long survival potential. The present review describes, based on published literature, the survival and behavior of Cryptosporidium oocysts in water, soil and other environmental surroundings as related to public health and infection prevention. As a zoonotic disease, cryptosporidiosis starts by infecting the intestinal tract of a large variety of mammals (~152 species) including humans. The excretion rate of oocysts (Cryptosporidium environmental stage) is high and favors the spread of this parasite to water and food sources. Such an extensive number is highly supportive for the wide spread of the parasite. Furthermore, a recent publication revealed that Cryptosporidium is not only an intracellular parasite but is also able to form a large or gigantic gamont-like stage-as additional extracellular life stage in vivo, where biofilm on gut cell surfaces may support Cryptosporidium growth and multiplication without the prerequisite for host cell invasion (inside the cell it acquires a unique epicellular location). This newly reported feature raises new question about its environmental survival. The agricultural link is obvious and its environmental impact involves soil, water and food once untreated waste water and effluents are applied for irrigation. These sources should be monitored for presence of Cryptosporidium to prevent infection and disease, and measures should be taken, such as water filtration, to prevent its spread to extended populations.