Sudden mortality in captive white-tailed deer (Odocoileus virginianus) with atypical infestation of winter tick (Dermacentor albipictus)

Authors: MACHTINGER, ERIKA - Pennsylvania State University; SPRINGER, HAYLEY - Pennsylvania State University; BROWN, JESSICA - Pennsylvania State University; Olafson, Pia

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2021
Publication Date: 3/25/2021
Citation: Machtinger, E.T., Springer, H.R., Brown, J.E., Olafson, P.U. 2021. Sudden mortality in captive white-tailed deer (Odocoileus virginianus) with atypical infestation of winter tick (Dermacentor albipictus). Journal of Medical Entomology. https://doi.org/10.1093/jme/tjab043.
DOI: https://doi.org/10.1093/jme/tjab043

Interpretive Summary: Winter ticks are common ectoparasites of cervids throughout their range. This tick species can carry and transmit several pathogens and can incite excessive grooming and premature loss of hair to some host species. In some cases, severe infestations can lead to death. Recently, mortality associated with severe winter tick infestation was documented in wild elk in Pennsylvania. White-tailed deer are considered a low-quality host for winter ticks and there have been no reports of severe negative effects associated with winter tick infestation on this species. While winter ticks were found in moderate numbers on hunter-harvested deer in 2019 in Pennsylvania, in 2020 three captive male white-tailed deer were found to have died with heavy infestations of winter ticks less than two weeks after being placed into protected paddocks in the central region of the state. A fourth buck was euthanized with a similar heavy infestation. Genetic analysis confirmed the tick identification. Because these deer have been raised in captivity, natural grooming behaviors may be impacted, or natural acquired resistance to ticks in this population may have been lost. This suggests that captive deer should be monitored for winter tick infestations and tick burdens should be considered before transporting captive deer.

Technical Abstract: In October 2020, three captive male white-tailed deer were found dead in central Pennsylvania, US and a fourth was euthanized due to extreme lethargy. The deer presented with high burdens of Dermacentor albipictus (winter tick). There were no other clinical symptoms and deer were in good physical condition with no observed alopecia. Winter tick epizootics have been associated with mortalities of moose, and more recently elk in Pennsylvania, but has not been reported in white-tailed deer. Mild winters are favorable to winter ticks and deer producers should be aware of possible infestations after regionally mild winters.