PREVALENCE AND CONCENTRATION OF CRYPTOSPORIDIUM PARVUM OOCYSTS IN BEEF CATTLE PADDOCK SOILS AND FORAGE

Authors: Boyer, Douglas; KUCZYNSKA, EWA - FORMER USDA POST-DOC

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2010
Publication Date: 7/28/2010
Citation: Boyer, D.G., Kuczynska, E. 2010. PREVALENCE AND CONCENTRATION OF CRYPTOSPORIDIUM OOCYSTS IN BEEF CATTLE PADDOCK SOILS AND FORAGE. Foodborne Pathogens and Disease. 7(8):893-900.

Interpretive Summary: Cryptosporidium parvum is pathogenic organism that infects humans and animals. It is important because of its widespread occurrence in surface waters, its high degree of infectivity, and the difficulty of controlling it. Information about environmental loading and the seasonal occurrence of Cryptosporidium is important for development of watershed management plans to protect public health. Healthy adult beef cattle are known to shed oocysts into the environment and Cryptosporidium parvum oocysts are often present all year in streams and groundwater in livestock agriculture areas. Surface soil and forage samples from 12 Virginia paddocks were analyzed bimonthly over three years for the presence and concentrations of Cryptosporidium oocysts. Half of the paddocks were grazed by stocker beef from November to September. The other half were managed for hay, but were grazed briefly by the same animals in late fall and early spring. More than half of the pasture soil and forage samples contained Cryptosporidium oocysts. More than 40 percent of the hay soils and vegetation contained Cryptosporidium oocysts. Cryptosporidium concentrations increased with increasing occurrences in the soil and on the forage in both management systems. Cattle and wild animals were sources of the Cryptosporidium oocysts. Canopy management, short-cycle rotational grazing, and control of wildlife are recommended as potential strategies for reduction of Cryptosporidium oocysts in pasture and lessening the risk of contamination of water supplies.

Technical Abstract: Cryptosporidium parvum is an enteric coccidian protozoan that receives a great amount of interest because of its widespread occurrence in surface waters, its high degree of infectivity, and the difficulty of risk management associated with its presence and control. Information about environmental loading and the seasonal prevalence of oocysts is important for development of watershed management plans to protect public health. Healthy adult beef cattle are known to shed oocysts into the environment and Cryptosporidium parvum oocysts are often present all year in streams and groundwater in livestock agriculture areas. Surface soil and forage samples from 12 Virginia paddocks were analyzed bimonthly over three years for the presence and concentrations of Cryptosporidium oocysts. Half of the paddocks were grazed by stocker beef from November to September. The other half were managed for hay, but were grazed briefly by the same animals in late fall and early spring. Annual mean prevalence in the soils was 57.9 and 48.4 percent in the pasture and hay paddocks, respectively. No seasonality of prevalence in the soils was observed. Mean oocyst prevalence on forage was 52.4 and 40.5 percent in the pasture and hay paddocks, respectively. Prevalence and concentration of oocysts on the hay forage was highest in summer and lowest in winter. Oocyst concentrations increased with increasing prevalences in the soil and on the forage in both management systems. Wild animals appeared to be sources of oocysts. Canopy management, short-cycle rotational grazing, and control of wildlife are recommended as potential strategies for reduction of Cryptosporidium oocysts in pasture and lessening the risk of contamination of water supplies.