BACKGROUND: Moose (Alces alces) are a culturally and economically valued species in Minnesota. However, the moose population has experienced a sudden, marked decline in their range, including extirpation in the northwest and a 66% decline in the last decade in the northeast portions of the state. Although the exact cause of this decline is unclear, parasitic metastrongylid and filarioid nematode infections are known causes of morbidity and mortality in moose across North America. METHODS: To determine if these parasitic nematodes could be contributing to the Minnesota moose population decline, we molecularly examined banked tissues obtained from moose that died of known and unknown causes for the presence of nematode DNA. Extracted brain DNA of 34 individual moose was amplified utilizing primers targeting the 18S rRNA gene and internal transcribed spacer regions of nematodes. RESULTS: DNA sequencing revealed that PCR products obtained from 15 (44.1%) of the moose were 99% identical to Parelaphostrongylus tenuis, a metastrongylid known to cause neurological disease and death. Additionally, brain tissue from 20 (58.8%) individuals yielded sequences that most closely aligned with Elaeophora schneideri, a parasite associated with neurological impairment but previously unreported in Minnesota. Setaria yehi, a common filarioid parasite of deer, was also detected in the brain tissue of 5 (14.7%) moose. Molecular screening of 618 captured tabanid flies from four trapping sites revealed E. schneideri was present (6%) in the Minnesota environment and transmission could occur locally. Prevalence rates among the flies ranged between 0-100% per trapping site, with Chrysops spp. and Hybomitra spp. implicated as the vectors. CONCLUSIONS: Ultimately, these data confirm that P. tenuis is widespread in the Minnesota moose population and raises the question of the significance of E. schneideri as a contributing factor to morbidity and mortality in moose.
Bibliographical noteFunding Information:
Funding for the research was provided by the Minnesota Department of Natural Resources Section of Wildlife and the University of Tennessee Department of Biomedical and Diagnostic Sciences. Fellowship funding for graduate student (CG) was provided by the University of Tennessee, Department of Microbiology.
The authors thank Rebecca Trout-Fryxell for her help with technical advice on tabanid molecular analysis. We would like to thank Carl Betlach and Sam-antha Schroth for their help in processing tabanid specimens. We would also like to thank Mabre Brand for her help in processing tabanids for molecular analysis. We also thank Amanda Hand (funded by the University of Tennessee College of Veterinary Medicine) for technical editing of the manuscript. Reference nematodes were generously donated by Kimberlee Beckmen at the Alaskan Department of Wildlife, Fish and Game, John Henningsen at the Wyoming State Veterinary Laboratory, Sauli Laaksonen of the Finnish Food Safety Authority and Kevin Keel of the University of Georgia.
- Elaeophora schneideri
- Moose (Alces alces)
- Parasitic infections
- Parelaphostrongylus tenuis