Statewide seasonal trends and small scale spatial patterns of fecal shedding of Cryptosporidium in California ground squirrels. Larsen, Royce^*,1, Atwill, Rob, Phillips, Ralph ³, Tate, Ken⁴, ¹ UC Cooperative Extension, Paso Robles, CA, USA³ UC Cooperative Extension, Bakersfield, CA, USA⁴ UC Cooperative Extension, Davis, CA

ABSTRACT- Waterborne transmission of pathogenic protozoa has emerged as an important public health concern. Given that the parasite readily infects a large number of mammalian hosts, there are a number of possible contributing sources of oocysts present for any given watershed. California ground squirrels have some of the highest rates of infection among the mammalian hosts. Current results show the prevalence of Cryptosporidium infection among California ground squirrels changes by season, age and location. Infection rates are lowest during winter and fall (can be less than 5%) and highest during spring and summer (can be greater than 50%). Juveniles have the highest infection rates that can be over 50 percent. The Infection rate in adults is less than juveniles, but can be higher than 30 percent. There does not appear to be any distinction between infection rates of individual squirrels in the small scale spatial pattern between different colonies. However, there may be differences of infection rates in squirrel populations in different areas of the state.

KEY WORDS: Pathogens, Water Quality, Rangeland