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ASSESSMENT OF DISEASE RISK ASSOCIATED WITH POTENTIAL REMOVAL OF ANTHROPOGENIC BARRIERS TO MOJAVE DESERT TORTOISE
Tristan L Burgess1, Josephine Braun2, Carmel L Witte2
1Acadia Wildlife Services, PO Box 56, South Freeport, Maine 04078, USA.
Journal of Wildlife Diseases
|May 21, 2021
Summary
Mojave Desert tortoise populations face threats from habitat loss and disease. Mycoplasma agassizii infection is linked to upper respiratory tract disease (URTD) clinical signs, with higher incidence observed at a translocation site, potentially impacting population connectivity.
Area of Science:
- Wildlife health
- Conservation biology
- Desert ecology
Background:
- The Mojave Desert tortoise (Gopherus agassizii), a threatened species, experiences habitat loss and fragmentation.
- Upper respiratory tract disease (URTD) poses a significant health risk to desert tortoise populations.
- URTD has been identified at the Large-Scale Translocation Study Site (LSTS) in Nevada.
Purpose of the Study:
- To estimate the prevalence of URTD and Mycoplasma infection in Mojave Desert tortoises at LSTS and nearby unfenced sites.
- To determine if Mycoplasma infection is associated with URTD clinical signs and if this association differs between fenced and unfenced areas.
- To analyze the longitudinal changes in Mycoplasma infection and its correlation with URTD development.
Main Methods:
- Sampling of 421 tortoises in 2016 across LSTS and three unfenced sites.
- Evaluation of URTD clinical signs (nasal discharge, ocular discharge, nasal erosions).
- Detection of Mycoplasma agassizii and Mycoplasma testudineum using quantitative PCR and ELISA.
Main Results:
- LSTS exhibited the highest prevalence of M. agassizii (25.0%), M. testudineum (3.0%), and URTD clinical signs (18.9%).
- M. agassizii infection was positively associated with URTD clinical signs (OR=7.7), with no difference between sites.
- Longitudinal data showed M. agassizii seroconversion in 3.2% of tortoises, with higher incidence at LSTS, and conversion was linked to increased URTD signs.
Conclusions:
- Mycoplasma agassizii infection is a significant factor in URTD development in Mojave Desert tortoises.
- While URTD is present outside LSTS, potential reconnection of populations could increase disease incidence.
- The risk of increased disease incidence must be weighed against the benefits of enhanced population connectivity for long-term viability.
Keywords:
Gopherus agassiziiMycoplasma agassiziiDisease risk assessmentMojave Desert tortoisetranslocationupper respiratory tract diseaseMore Related Videos
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