Undetectable Mycobacterium leprae complex in European Pallas's squirrels

Area of Science:

• Veterinary Microbiology
• Zoonotic Diseases
• Wildlife Health

Background:

• Eurasian red squirrels are known reservoirs for Mycobacterium leprae in the British Isles.
• Leprosy in squirrels poses a potential zoonotic risk.
• Pallas's squirrels (Callosciurus erythraeus) have been introduced to the European continent.

Purpose of the Study:

• To investigate the potential for Pallas's squirrels in Europe to act as reservoirs for Mycobacterium leprae.
• To determine if introduced Pallas's squirrels harbor leprosy-causing bacteria.
• To assess the risk of zoonotic leprosy transmission from continental squirrel populations.

Main Methods:

• Analysis of 522 samples (liver, spleen, faecal) from 281 deceased Pallas's squirrels.
• Quantitative PCR targeting specific repetitive elements of Mycobacterium leprae and Mycobacterium lepromatosis.
• Inclusion of an internal control to ensure PCR accuracy and absence of inhibition.

Main Results:

• All tested samples were negative for Mycobacterium leprae complex DNA.
• No evidence of leprosy-causing bacteria was detected in the Pallas's squirrel population studied.
• PCR inhibition was ruled out by successful amplification of internal controls.

Conclusions:

• Introduced Pallas's squirrels in continental Europe do not appear to be reservoirs for systemic leprosy.
• Current data suggest zoonotic leprosy in Europe is restricted to the red squirrel population of the British Isles.
• Further research may be needed to investigate localized infections or different geographical areas.