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Echinococcus multilocularis infection is more prevalent in young coyotes (Canis latrans) with varied effects of diet
- Author / Creator
- Steckler, Deanna Kari
Urban environments can influence parasite transmission and prevalence by altering the diets, distribution, abundance, and behaviour of wildlife. Echinococcus multilocularis is a zoonotic cestode that typically parasitizes coyotes (Canis latrans) and rodents (Myodes spp., Microtus spp.) as definitive and intermediate hosts, respectively. E. multilocularis has historically been widespread among Canadian wildlife, however, it is of emerging concern because a variant of a European strain is associated with 17 human infections, primarily in Alberta. This variant is now widespread among coyotes in the province and the pathogen appears to be especially prevalent among urban coyotes in Edmonton. I hypothesize that an altered diet in urban coyotes contributes to a higher prevalence of E. multilocularis either by (a) greater exposure from consumption of infected rodents, or (b) increased overall susceptibility to infection from consumption of anthropogenic food that may reduce body condition.
I tested these hypotheses by examining coyote carcasses donated from urban and rural sources in and near Edmonton. In close collaboration with other researchers, I compared the presence and intensity of E. multilocularis infection in the carcass intestine to physiological data (cementum age, sex, body condition) and measures of short and long-term diet (stomach contents, stable isotope values). E. multilocularis was detected in the intestine by molecular testing (qPCR) and quantified by worm counts of filtered intestinal contents. Long-term diet was tested for prey (δ15N) and anthropogenic food (δ13C) stable isotopic values. Stomach contents were separated into 10 diet components: prey (ungulates, rodents, meso-mammals, birds), vegetation (herbaceous, woody), native fruit, insects, anthropogenic food (digestible, indigestible). I examined the effects that consumption of rodents and anthropogenic food had on the presence of E. multilocularis with logistic regression models and the intensity of infection with a negative binomial generalized linear model. I analyzed each location separately and accounted for the effect of age.
I detected E. multilocularis DNA in 70% of coyote intestines and worms were detected in 48%. Edmonton’s urban coyotes exhibited infection prevalence much higher than other Canadian locations. We found few direct short- and long-term diet differences between infected and uninfected coyotes until we assessed urban and rural coyotes separately, which revealed that the volumes of rodents and anthropogenic food related to E. multilocularis infection differently in each location. Unexpectedly, uninfected urban coyotes consumed large volumes of rodents, primarily as older adults. Similarly, the presence and intensity of E. multilocularis infection in rural coyotes was most strongly driven by young age, but uninfected rural coyotes also consumed large volumes of digestible anthropogenic food. Young coyotes hosted the most intense infections and young, urban coyotes that consumed greater quantities of rodents and anthropogenic food were more likely to be infected. Taken together, our results suggest that young age is the most important contributor to the presence and intensity of E. multilocularis infection in coyotes and aspects of young coyote ecology, such as diet composition, may increase the likelihood of becoming infected.
- Graduation date
- Fall 2021
- Type of Item
- Master of Science
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