Decay of Cryptosporidium parvfum DNA in cowpats in subtropical environments determined using qPCR

Abstract

Cryptosporidium oocysts pose a significant threat to public health due to its ability to contaminate environmental waters, leading to outbreaks of waterborne diseases and emphasizing the crucial need for effective water treatment and monitoring systems. This study aimed to investigate the decay of Cryptosporidium oocyst DNA in cow fecal matter under different environmental conditions prevalent in sub-tropical Southeast Queensland (SEQ) during summer and winter seasons. The effects of ambient sunlight and shaded conditions on the decay rates of C. parvum DNA in cow fecal samples were evaluated. The results showed that measurable levels of C. parvum DNA were observed for up to 60 days during the summer experiments, with a slower decay rate on the surface (k = -0.029) and sub-surface (k = -0.043) of the cowpat under shaded conditions than those on the surface (k = -0.064) and sub-surface (k = -0.079) under sunlight conditions. The decay rates of C. parvum DNA on the surface and sub-surface of the cowpat under shaded conditions were significantly slower (p = 0.004; p = 0.004) than those on the surface and sub-surface under sunlight conditions during summer experiments. During the winter treatments, measurable levels of C. parvum DNA were observed for up to 90 days, and the decay rates were slower on the surface (k = -0.036) and sub-surface (k = -0.034) of the cowpat under shaded conditions than those under sunlight conditions (k = -0.067 for surface and k = -0.057 for sub-surface). The decay rates of C. parvum DNA on the surface and sub-surface of the cowpat under shaded conditions were significantly slower than those on the surface (p = 0.009) and sub-surface (p = 0.041) under sunlight conditions during winter experiments. Moreover, the decay rate in the summer sunlight surface treatment (k = -0.064) was significantly faster from those in the winter shaded surface (k = -0.036; p = 0.018) and sub-surface (k = -0.034; p = 0.011) treatments. Similar results were also observed for summer sunlight sub-surface (k = -0.079), which was significantly faster than winter shaded surface (k = -0.036; p = 0.0008) and sub-surface (k = -0.034; p = 0.0005) treatments. Overall, these findings are important to enhance our understanding on the degradation of C. parvum DNA in cow fecal matter in SEQ, particularly in relation to seasonal variations and environmental conditions.

Keywords: C. parvum; Cowpat; Decay rates; Human health risks; Water quality.