Intensity Characterization of Fecal Shedding of cryptosporidium and Risk Factors In Sheep Farms In California, USA - Abstract
n epidemiological study was conducted to investigate the prevalence of Cryptosporidium spp. and intensity of fecal shedding of oocysts in sheep and to identify risk factors in sheep farms in California, USA. A total of 798 fecal samples from 372 adult ewes, 31 yearlings, and 395 lambs were collected from 16 ranches in central and northern California. Quantitative detection of Cryptosporidium oocysts in feces were performed using a direct immunofluorescent assay. The overall prevalence of Cryptosporidium spp. was 30.6% (121/395) in lambs, 16.1% (5/31) in yearlings, and 3.2% (12/372) in adult ewes. High prevalence was observed in 60-day old [37.4% (61/163)] and 90-day old [38.3% (41/107)] lambs. Infected lambs and adult ewes shed up to 6.8 ×106and 1 ×106oocystsper animal per day, respectively. Farm management practices, flock, and sheep information were collected from each ranch during each sampling event and used for statistical analysis of risk factors associated with the prevalence of fecal shedding of Cryptosporidium oocysts. Access to surface sources of drinking water (odd ratio=1.8) and contact with cattle (odd ratio=3.8) significantly increased the fecal shedding of oocysts in sheep of all ages. The odds of fecal shedding of oocysts in lambs decreased as the number of ewes increased in the flock and the odds of fecal shedding of oocysts in adult ewes decreased as the pasture size increased. Fecal shedding of Cryptosporidium oocysts was not significantly associated with diarrhea in sheep.
Importance: Cryptosporidium is an important parasite infects a wide range of vertebrates including livestock. Cryptosporidium infection in sheep impacts animal health and fecal shedding of oocysts impacts environmental health. Studying the prevalence and risk factors of fecal shedding Cryptosporidium in sheep is an important part of controlling the infection and protecting the health of sheep and the environment. This work not only determined variable prevalence of Cryptosporidium in lambs, yearlings and ewes in sheep farms and shedding intensity and environmental loading rate, but also identified accessing to surface water and contacting with cattle increased the odds of sheep infection.Incorporating this information to beneficial management practices can reduce the fecal shedding of Cryptosporidium in sheep and subsequently reduce environmental loading of this parasite.