Pathology and epidemiology of nasopulmonary acariasis (Halarachne sp.) in southern sea otters (Enhydra lutris nereis)

Colleen E Shockling Dent; Melissa A Miller; Francesca Batac; Erin Dodd; Woutrina Smith; Risa Pesapane; Janet Foley

doi:10.1016/j.ijppaw.2019.03.009

Pathology and epidemiology of nasopulmonary acariasis (Halarachne sp.) in southern sea otters (Enhydra lutris nereis)

Int J Parasitol Parasites Wildl. 2019 Mar 24:9:60-67. doi: 10.1016/j.ijppaw.2019.03.009. eCollection 2019 Aug.

Authors

Colleen E Shockling Dent¹, Melissa A Miller^{2

3}, Francesca Batac², Erin Dodd², Woutrina Smith^{3

4}, Risa Pesapane⁴, Janet Foley⁴

Affiliations

¹ College of Veterinary Medicine, The Ohio State University, 1900 Coffey Road, Columbus, OH, 43210, USA.
² California Department of Fish and Wildlife, Marine Wildlife Veterinary Care and Research Center, 151 McAllister Way, Santa Cruz, CA, 95060, USA.
³ One Health Institute, School of Veterinary Medicine, University of California, 1089 Veterinary Medicine Dr., Davis, CA, 95616, USA.
⁴ Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, One Shields Ave., Davis, CA, 95616, USA.

Abstract

Halarachne sp. nasal mites infest harbor seals (Phoca vitulina) and southern sea otters (Enhydra lutris nereis) in California, but little is known about the pathophysiology of these infestations, or risk factors for exposure. To investigate these questions, a retrospective case-control study was performed using necropsy data from 70 mite-infested sea otters, and 144 non-infested controls. Case records for sea otters examined by pathologists from February 1999 through May 2015 were examined to assess risk factors for infestation, and lesions associated with nasopulmonary acariasis. Animals with a history of captive care within 10 days of death or carcass recovery were 3.2 times more likely to be infested with nasopulmonary mites than those with no history of recent rehabilitation. Sea otters stranding within 1 km of Elkhorn Slough in Monterey Bay were 4.9 times more likely to be infested with nasal mites than other areas; this site is characterized by high sea otter contact with sympatric harbor seals (a common host for Halarachne sp.), and a comparatively large population of rehabilitated and released sea otters. Aged adult otters were 9.4 times more likely to be infested than younger animals, and sea otters with nasopulmonary acariasis were 14.2 times more likely to have upper respiratory inflammation than un-infested animals. Additional findings in otters with nasopulmonary acariasis included lower respiratory tract bacterial infections, presence of medium-sized and/or fresh nose wounds at necropsy (indicators of recent face-to-face interaction between otters during copulation or fighting), and turbinate bone erosion. Our findings, although preliminary, suggest that captive rehabilitation and close contact with harbor seals could facilitate nasopulmonary mite transmission to sea otters. We also identified a high-risk zone for nasopulmonary acariasis in sea otters. We also provide preliminary data to suggest that nasopulmonary mite infestations can cause significant respiratory pathology in sea otters.

Keywords: Enhydra lutris; Epidemiology; Halarachne sp.; Nasal (nasopulmonary) mite; Risk factor; Sea otter.