Cryptosporidium Contamination Research Articles

The prevalence of Cryptosporidium/Giardia in the trail horse population utilizing public lands in Colorado

SummaryCryptosporidium and Giardia spp. are small coccidian parasites that infect the intestinal tract of birds, reptiles and mammals including humans. Oocysts of Cryptosporidium parvum and cysts of Giardia duodenalis are shed in the feces of infected animals and directly infect subsequent hosts following ingestion. The broad host range, resistant nature, and small size of the parasites in the environment may potentially contribute to contamination of water supplies. The perception that recreational riding horses may increase the prevalence of Cryptosporidium and Giardia in large watersheds adjacent to common trails, indirectly infecting humans, has resulted in banning recreational riding horses from some trails. However, there is currently no scientific data linking the recreational trail horse to the incidence or increased risk of human cryptosporidiosis or giardiasis. This survey was conducted to determine the prevalence of Cryptosporidium and Giardia spp. in recreational horses utilizing trails located near large watershed areas in Colorado. At the trail heads, approximately 10 g of fresh feces were collected from recreational horses (n=300) that were utilizing the trails on the day they were sampled. Fecal samples were mixed with 10% formalin at a dilution rate of 1 part feces to 4 parts formalin and were transported to the Veterinary Diagnostic Laboratory at Colorado State University. Samples were evaluated using the Merifluor™Cryptosporidium/Giardia Direct Immunofluorescent Detection Procedure. One horse (0.33%) was detected positive for Cryptosporidium and two horses (0.66%) were positive for Giardia. The low prevalence of Cryptosporidia and Giardia in the trial horse population surveyed indicates that the adult recreational trail horse population is not likely to be a significant source of Cryptosporidium and Giardia environmental contamination in watershed areas.

Zoonotic transmission of Cryptosporidium parvum: Implications for water-borne cryptosporidiosis

The emergence of Cryptosporidium parvum-associated cryptosporidiosis as a worldwide zoonosis has stimulated interest in the modes of pathogen transmission. Here, Thaddeus Graczyk, Ronald Fayer and Michael Cranfield discuss the complex epidemiology of C. parvum, emphasizing the crosstransmission potential of the pathogen, mechanical vectors involved in water-borne transmission of the oocysts, and factors contributing to contamination of pristine waters with Cryptosporidium. They also outline the public health importance of proper interpretation of positive detection of Cryptosporidium oocysts at water-treatment facilities and identify means by which watersheds can be protected from Cryptosporidium contamination.

Waterborne Disease Outbreaks, 1986–1988

From 1986 to 1988, 24 states and Puerto Rico reported 50 outbreaks of illness due to water that people intended to drink, affecting 25,846 persons. The protozoal parasite Giardia lamblia was the agent most commonly implicated in outbreaks, as it has been for the last 10 years; many of these outbreaks were associated with ingestion of chlorinated but unfiltered surface water. Shigella sonnei was the most commonly implicated bacterial pathogen; in outbreaks caused by this pathogen, water supplies were found to be contaminated with human waste. Cryptosporidium contamination of a chlorinated, filtered public water supply caused the largest outbreak during this period, affecting an estimated 13,000 persons. A large multistate outbreak caused by commercially produced ice made from contaminated well water caused illness with Norwalk-like virus among an estimated 5,000 persons. The first reported outbreak of chronic diarrhea of unknown cause associated with drinking untreated well water occurred in 1987. Twenty-six outbreaks due to recreational water use were also reported, including outbreaks of Pseudomonas dermatitis, associated with the use of hot tubs or whirlpools, and swimming-associated shigellosis, giardiasis, and viral illness. Although the total number of reported water-related outbreaks has been declining in recent years, the few large outbreaks due to Cryptosporidium, Norwalk-like agent, S. sonnei, and G. lamblia caused more cases of illness in 1987 than have been reported to the Water-Related Disease Outbreak Surveillance System for any other year since CDC and the Environmental Protection Agency began tabulating these data in 1971.