Abstract
Orthohalarachne attenuata is a nasal mite commonly found in the nasal turbinates and nasopharynx of wild pinnipeds including California sea lions (Zalophus californianus). Orthohalarachne typically do not cause clinical disease; however, clinical signs of infection can range from sneezing and nasal discharge to lung infections.1,2 Nasal mites are traditionally diagnosed by detection of the mite in nasal secretions.1
In this case, a 17-year-old adult female walrus presented for copious inflammatory nasal discharge for ~ 1 week's duration. The patient is housed with two additional walrus that were considered clinically normal. The patient had a normal appetite and attitude. Treatment with doxycycline (4 mg/kg PO BID) was initiated for a bacterial rhinitis based on culture results from the nasal discharge. The amount of nasal discharge decreased dramatically, and after three weeks of treatment, doxycycline was discontinued. The nasal discharge returned within two weeks, and the walrus started having difficulty breathing through her nares. Blood work was performed and revealed a leukocytosis with a mature neutrophilia. A nasal swab culture revealed mostly contaminant bacteria with no fungal growth. Doxycycline was restarted for a few weeks, and the discharge improved but the rhinitis continued. Thoracic ultrasound and skull radiographs were performed and considered normal. The patient's appetite started to decline, and she became mildly lethargic. Cytology of the nasal discharge revealed marked mucopurulent discharge with no etiology identified. Voluntary endoscopy of the anterior nasal cavity was then pursued in order to obtain deeper samples for cytology and culture and to visualize the nasal turbinate mucosa. Within four weeks the walrus trainers were able to de-sensitize all three walrus to having the endoscope placed ~ 3–5 cm into the nares without using sedation or local anesthesia. The initial scoping in the clinical walrus revealed mucus surrounding white to yellow raised material with filamentous structures, which were collected. The nasal turbinate mucosa was mildly inflamed. The structures were examined microscopically in-house and determined to be nasal mites.
The mites were sent to the National Marine Life Center and were determined to be Orthohalarachne attenuata. The nasal mite was identified in all three walrus but the largest burden was in the clinical walrus. All three walrus were treated with ivermectin 0.2 mg/kg PO once, and then repeated two weeks later.1 The walrus handled the ivermectin treatment well and were free of the mites when the scoping was repeated three weeks later. This report highlights the importance of medical training in order to accomplish critical diagnostics without the risk of anesthesia.
Acknowledgments
We thank the marine mammal staff at Six Flags Discovery Kingdom for their dedication to excellent and innovative training and for their patience throughout this case. We also thank Kelly Goulet, Dawn Robles and Eric Calvo for their hard work and support.
* Presenting author
Literature Cited
1. Dierauf LA, Gulland FMD. CRC Handbook of Marine Mammal Medicine. New York: CRC Press; 2001:372.
2. Kim KC, Haas VL, Keyes MC. Populations, microhabitat preference and effects of infestation of two species of Orthohalarachne (Halarachnidae: Acarina) in the northern fur seal. J Wildl Dis. 1980;16:45–51.