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Detection and Eradication of a Demodex Infestation in Specific Pathogen-free High-barrier Laboratory Mouse Facility
Samantha Le Sommer1, Yan Sun1, Levi Legler1
1Department of Biomedical Research and Translational Medicine, Masonic Medical Research Institute, Utica, New York.
Abstract:
Demodex mites are a common ectoparasite in nonlaboratory Mus musculus (mouse) populations. While infrequently reported in laboratory research mice, the prevalence is thought to be as high as 35% of all colonies. Here, we discuss an outbreak of Demodex within an SPF high-barrier vivarium housing laboratory mice first identified through commercial sentinel-free PCR testing. Consequently, in-house PCR-mediated identification of individually infected cages was conducted, and a successful method for eradication of secondary reemergent infection was generated via recurrent testing and empirical 12-wk treatment with 3 mg/kg moxidectin and 13 mg/kg imidacloprid. While we were unable to determine the source of our primary outbreak, the secondary outbreak was traced to nongenetically modified C57B6/J immunocompetent mice, which were capable of harboring subclinical infection below our PCR threshold. Our eventual successful eradication of Demodex confirmed, first, that in-house PCR detection is a cost-effective means of monitoring an outbreak; second, that treatment with 3 mg/kg moxidectin and 13 mg/kg imidacloprid does kill Demodex mites in laboratory mice; and third, that treatment of only PCR-positive mice is an insufficient way to control an outbreak. Taken together, our methodological approach for infestations such as Demodex suggests it is possible to eradicate them but that it requires a thorough, systematic, and aggressive treatment regimen. Moreover, we recommend that all cages derived from infected animals be treated as positive, regardless of PCR positivity, to prevent recurrent and/or persistent infections within an animal colony.
Insights
Demodex mite infestations in lab mice can be eradicated using a rigorous PCR testing and moxidectin/imidacloprid treatment regimen. Treating all cages from infected animals is crucial for preventing re-infection.
Area of Science:
- Veterinary Parasitology
- Laboratory Animal Science
- Infectious Disease Control
Background:
- Demodex mites are common ectoparasites in wild mice, with up to 35% prevalence in laboratory mouse colonies.
- Infestations are infrequently reported but can impact research integrity.
- This study details an outbreak in a specific SPF vivarium.
Purpose of the Study:
- To describe the identification and successful eradication of a Demodex mite outbreak in a laboratory mouse vivarium.
- To evaluate the efficacy of PCR testing and a specific drug combination for Demodex control.
- To establish a comprehensive eradication strategy for Demodex in research settings.
Main Methods:
- Initial identification via commercial sentinel-free PCR testing.
- In-house PCR for cage-level diagnosis.
- 12-week empirical treatment with moxidectin (3 mg/kg) and imidacloprid (13 mg/kg).
- Tracing secondary outbreak to immunocompetent mice with subclinical infections.
Main Results:
- In-house PCR proved cost-effective for monitoring Demodex outbreaks.
- Moxidectin and imidacloprid combination effectively killed Demodex mites in laboratory mice.
- Treating only PCR-positive cages was insufficient for outbreak control.
- Secondary outbreak traced to subclinical infections in C57B6/J mice.
Conclusions:
- Demodex eradication is achievable but requires a systematic and aggressive approach.
- Treating all cages derived from infected animals is essential to prevent recurrent infections.
- PCR detection is a valuable tool, but comprehensive treatment protocols are paramount for successful control.
