Surveillance for Rodent External Parasites at Sheep River Provincial Park, Alberta.

Rodents often are reservoirs for numerous infectious agents, or pathogens, that can be transmitted from animals to humans. External parasites such as fleas, ticks and mites that reside on rodents can act as carriers and assist in transmitting diseases to humans.  This is how a large number of emerging diseases that humans contract from animals are being transmitted and these pathogens are anticipated to expand their range under current climate change scenarios; there is therefore a growing interest in active surveillance for rodent pathogens and their carriers. During the summer of 2012, the Alberta Canadian Cooperative Wildlife Health Centre office led a surveillance project at Sheep River Provincial Park (SRPP) to document the external parasites found on rodents and test them for pathogens that have the potential to be transmitted to humans.

SRPP is located 100 km southwest of Calgary, Alberta in the foothills of the Rocky Mountains. This park is heavily used by people, has seasonal cattle grazing, and thus there is a significant interface between humans, domestic animals and wildlife. The project involved live rodent trapping to collect and identify external parasites, and detect the pathogens that they carried.  Michael Zabrodski, a DVM student at the University of Calgary Veterinary Medicine (UCVM) college was hired as a summer student to work on this project. He was funded by the Merial Veterinary Scholar Program, the Natural Sciences and Engineering Research Council of Canada (NSERC) and the UCVM to carry out this study. Jesse Patterson, a Biological Sciences PhD student at University of Calgary who is studying red squirrels and their parasites, guided the field sampling.

Over the summer, 224 rodents were trapped and 872 external parasites (fleas, ticks, lice and mites) were collected. Fleas were abundant in our collection and were processed for species identification. Overall, 10 different species of fleas were recorded from five different rodents – American Red Squirrel, Colombian Ground Squirrel, Southern Red-backed Vole, Yellow-pine chipmunk and Least chipmunk. The ticks collected were mostly at young stages and the species are yet to be identified. The presence of potential insect-borne pathogens that can also infect humans is currently being evaluated by screening fleas and ticks for agents that cause Plague (Yersinia pestis), Rocky Mountain spotted fever (Rickettsia sp.), Tularemia (Francisella tularensis), Lyme Disease (Borrelia burgdoferi), Babesiosis (Babesia microti), and Human Granulocytic Ehrlichiosis (Anaplasma phagocytophilia). Although analysis of samples collected from the park is ongoing, preliminary results confirm the presence of a Francisella sp in fleas.

Flea Photos courtesy: Michael Zabrodski, Mani Lejeune

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