Water Resources Research Act Program

Details for Project ID 2009ND183B

Source tracking of Cryptosporidium in rural watersheds

Institute: North Dakota
Year Established: 2009 Start Date: 2009-03-01 End Date: 2012-02-29
Total Federal Funds: $28,999 Total Non-Federal Funds: $58,001

Principal Investigators: John McEvoy, Mark Clark

Project Summary: The Upper Midwest has among the highest incidences of human cryptosporidiosis in the U.S. There is therefore a critical need to determine Cryptosporidium sources and transmission dynamics in this region. One of our previous studies has shown that most human cryptosporidiosis in the region is caused by C. parvum, a species associated with humans and cattle. However, the traditional model, describing Cryptosporidium movement from livestock to humans via water, appears over simplistic in light of recent evidence of wildlife sources of contamination. Cryptosporidium species associated with wildlife are not human pathogens and are not a public health threat. To better understand the human health significance of Cryptosporidium in rural watersheds, we need to determine the source of the contamination. This will be addressed by quantifying the impact of the wildlife and cattle sources in rural watersheds in the region. This project will have regional, national, and international relevance and will be critical to the guidance of future policies on the control of Cryptosporidium transmission in water. Objectives are to determine the extent of Cryptosporidium host adaptation and co-evolution with hosts, and to determine the factors influencing the contributions of cattle and wildlife to Cryptosporidium in rivers. We expect to find that most Cryptosporidium species have coevolved with a particular host and infect only this host and a small number of related hosts. However, we also expect to find evidence that species have jumped hosts in the recent past (as is likely the case for C. parvum). Identifying and understanding the exceptions will be critical to the success of subsequent Cryptosporidium source tracking studies. The prevalence of different wildlife and cattle associated Cryptosporidium species will be dependent on host abundance, prevalence of the parasite in the host population, and the number of oocysts being shed. As host numbers and parasite shedding rates fluctuate throughout the year, we expect to observe corresponding changes in the numbers and prevalence of Cryptosporidium in river samples. Results will be used to predict when different host species are likely to be significant sources of surface water contamination. For example, deer are known to herd more in the fall months and this may correlate with an increased environmental load of deer associated cryptosporidia and a corresponding increase in water prevalence.