Clinical Progression of leprosy in Eurasian red squirrels (Sciurus vulgaris) in A Naturally infected wild population

Anna Schilling, Anouk van Hooij, Peter Lurz, Darren Shaw, Annemieke Geluk, Paul L A M Corstjens, Karen Stevenson, Anna Meredith*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Leprosy has been described in Eurasian red squirrel (ERS) carcasses since 2014. Studies of ERS carcasses have not provided information about incubation or disease progression in this host but have provided important insights into pathogen presence and distribution throughout the UK. Here we present field study data on live ERS from an island population
naturally infected with Mycobacterium leprae that were assessed longitudinally over a two year time period. Clinical assessment, serological (anti-phenolic glycolipid-I antibody, αPGL-I, detection) and molecular methods (polymerase chain reaction, PCR) were used to diagnose and categorize ERS at each assessment as a leprosy case, leprosy suspect, colonized by M. leprae, or
contact ERS. Eight ERS (25.8%) were identified as leprosy cases: four at initial assessment, two at six months and two at 24 months after initial assessment. One ERS was categorized a leprosy suspect when it developed typical lesions 12 months after initial assessment, despite negative serological and molecular test results at this time, though M. leprae Desoxyribonucleic acid (DNA) had been isolated during the initial assessment. Seven ERS (22.6%) were categorized as
colonized and of these, six were re-assessed but did not develop clinical signs of leprosy within 6 (n=2), 12 (n=3), and 18 (n=1) months. Most (48.4%, n=15) were categorized as contact ERS. Progression of leprosy lesions varied between ERS, but always increased in severity over time and was paralleled with increased antibody response. Based on our dataset, we propose the hypotheses: a) leprosy in ERS is a chronic, slowly progressing disease in this species, similar to
that described for other hosts; b) lesions can undergo repeated ulceration-healing cycles; and c) in some instances M. leprae DNA and αPGL-I antibodies are detectable before the onset of clinical signs of disease. Future studies addressing the progression of leprosy in ERS should follow affected animals over a longer time period and include tissue samples to pair molecular diagnostics with serologic results.
Original languageEnglish
Pages (from-to)1159-1166
Number of pages8
JournalJournal of Zoo and Wildlife Medicine
Issue number4
Early online date16 Dec 2021
Publication statusE-pub ahead of print - 16 Dec 2021


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