Detection of humoral immunity to mycobacteria causing leprosy in Eurasian red squirrels (Sciurus vulgaris) using a quantitative rapid test

Eurasian red squirrels ( Sciurus vulgaris , ERS) in the British Isles are a recently discovered natural host for Mycobacterium leprae and Mycobacterium lepromatosis . Infected squirrels can develop skin lesions or carry the bacteria without showing clinical signs. Until now the clinical diagnosis of leprosy could only be confirmed in squirrels by isolating DNA of leprosy bacilli from carcasses or by establishing the presence of acid-fast bacilli in skin sections of carcasses with clinical signs. In this study, we assessed the performance of a field-friendly diagnostic test for detection of M . leprae / M . lepromatosis infection in ERS. This up-converting phosphor lateral flow assay (UCP-LFA) is well established for detection of M . leprae specific anti-phenolic glycolipid-I antibodies (αPGL-I) IgM antibodies in humans and associated with bacterial load. Assessment was performed on serum and blood drops from live squirrels and body cavity fluid samples from dead squirrels. Clinically diseased squirrels showed significantly higher αPGL-I levels than healthy animals or subclinically infected individuals ( p