Exposure to Select Pathogens in an Expanding Moose (Alces alces) Population in North Dakota, USA

Forty female moose (Alces alces) captured in North Dakota, US, in March 2014 were tested for antibodies to a variety of pathogens. Antibodies to West Nile virus (WNV) were detected in 39 (98%) moose following a year with a high number of human cases, suggesting the population accurately reflects WNV activity. Fifteen percent of moose (6/40) had antibodies to Borrelia burgdorferi, implying expansion of the tick vector into the area. Antibodies to Anaplasma spp. were detected in 55% of moose (22/40), a higher rate than previously detected in cattle from the region. Low titers (100-400) to one or more serovars of Leptospira spp. were detected in 23% of moose (9/40), a common finding in wild ruminants. Exposure to other pathogens was uncommon (<8%; <3/40) or not documented. Survival and recruitment were high during the study period, suggesting a limited population-level impact at current levels of exposure and environmental co-stressors.