Evaluation of the Effect of Temperature on the Die-Off Rate for Cryptosporidium parvum Oocysts in Water, Soils, and Feces

Abstract

The zoonotic protozoan parasite Cryptosporidium parvum poses a significant risk to public health and has become a global concern for water resource management (10). In order to identify the risk of potential contamination, knowledge about the survival of Cryptosporidium oocysts in the environment is required. Cryptosporidium oocysts can retain infectivity for months and resist environmental stresses more readily than many other pathogens because of a hard protective wall (10, 15, 41). As a result, the characterization of the die-off dynamics of C. parvum oocysts in the environment has received much attention (26). In this paper, we review the published data of the last two decades and the derived understanding of the relationships between temperature, one of the most important environmental stresses, and the die-off of C. parvum in water, soils, and feces. In general, the inactivation of Cryptosporidium oocysts in the environment slows down exponentially with time, presenting shoulder and tailing effects (31, 38). To cater for these two functions, a first-order exponential formula has usually been used to simulate the die-off curves for oocysts in water (5, 9, 18, 21), in soils (8, 20, 28), and in feces (30, 35), with equation 1 as follows: