Cryptosporidium oocysts

Montecino-Latorre, Diego, Li, Xunde, Xiao, Chengling & Atwill, Edward R., 2015, Elevation and vegetation determine Cryptosporidium oocyst shedding by yellow-bellied marmots (Marmota flaviventris) in the Sierra Nevada Mountains, International Journal for Parasitology: Parasites and Wildlife 4 (2), pp. 171-177 : 174

3.1. Fecal shedding of Cryptosporidium oocysts

A total of 224 fecal samples were collected. Thirty three (~15%) fecal samples had detectable levels of Cryptosporidium oocysts (95% CI: 10.0–19.4%). Among these 33 positive fecal samples, 22 had one oocyst, 6 had 2 oocysts, 2 had 4 oocysts and one of each had 8, 26 and 35 oocysts per smear. This distribution of oocyst shedding intensity resulted in a mean of 535 oocysts per gram of feces wet weight (95% CI: 204–865), ranging from 35 to 1,646 and a median value of 129 oocysts per gram of feces. The mean ELR was estimated as 10,693 Cryptosporidium oocysts per adult marmot per day.

Elevations of the sample collection sites ranged from 6,985 to 11,070 ft, with a median elevation of 9,068 ft. Total sample size of sites with and without vegetation was 158 and 66 respectively, with a median elevation of 8,657 and 9,374 ft, respectively. Bridaveil Creek, Chocolate Lakes, Courtright Reservoir, Lembert Dome, Pothole Dome, and Tenaya Creek were accessed from dirt/paved roads and the remaining locations were reached through hiking trails. The prevalences of Cryptosporidium oocysts in fecal samples collected at sites with and without vegetation were 11% and 23%, respectively. A summary of the number of samples collected by location and the positive proportion is presented in Table 2.