Spatio-temporal dynamics and aetiology of proliferative leg skin lesions in wild British finches

Abstract

Proliferative leg skin lesions have been described in wild finches in Europe although there have been no large-scale studies of their aetiology or epizootiology to date. Firstly, disease surveillance, utilising public reporting of observations of live wild finches was conducted in Great Britain (GB) and showed proliferative leg skin lesions in chaffinches (Fringilla coelebs) to be widespread. Seasonal variation was observed, with a peak during the winter months. Secondly, pathological investigations were performed on a sample of 39 chaffinches, four bullfinches (Pyrrhula pyrrhula), one greenfinch (Chloris chloris) and one goldfinch (Carduelis carduelis) with proliferative leg skin lesions and detected Cnemidocoptes sp. mites in 91% (41/45) of affected finches and from all species examined. Fringilla coelebs papillomavirus (FcPV1) PCR was positive in 74% (23/31) of birds tested: a 394 base pair sequence was derived from 20 of these birds, from all examined species, with 100% identity to reference genomes. Both mites and FcPV1 DNA were detected in 71% (20/28) of birds tested for both pathogens. Histopathological examination of lesions did not discriminate the relative importance of mite or FcPV1 infection as their cause. Development of techniques to localise FcPV1 within lesions is required to elucidate the pathological significance of FcPV1 DNA detection.

Scaly leg due to Knemidokoptes sp. in a bullfinch (Pyrrhula pyrrhula): Common is common, but keep an open mind for new findings!

“…It might be that the high number of Mesalgoides outnumbered the Knemidokoptes and gave a false negative result for Knemidokoptes at the skin scraping, or possibly the number of Knemidokoptes was low due to the therapy, or a combination of both. For the diagnostic workup of proliferative skin lesions of finches, it has been already highlighted the importance of laboratory examinations for the detection of papillomavirus, Knemidokoptes mites and avipox virus 3,4 . In our case, an extensive diagnostic workup identified the aetiology of the proliferative skin lesions.…”

Atypical Knemidokoptosis in Two Dunnocks (Prunella modularis) in Southern England

“…Most reports of knemidokoptosis in wild birds involve gregarious passerines such as the American robin (Turdus migratorius) and the common chaffinch (Fringilla coelebs) (Lawson et al, 2018a;Pence et al, 1999). In Great Britain (GB), knemidokoptosis is widespread in chaffinches and also occurs, albeit less frequently, in greenfinches (Chloris chloris), goldfinches (Carduelis carduelis), bullfinches (Pyrrhula pyrrhula), rooks (Corvus frugilegus), jackdaws (Corvus monedula) and carrion crows (Corvus corone) (Pennycott, 2016;Lawson et al, 2018a;). Whilst most cases in wild birds appear to be mild or moderate, it has been proposed that severe lesions may predispose individuals to predation, trauma or co-infection (Pence 2008;Lawson et al 2018a).…”

“…In Great Britain (GB), knemidokoptosis is widespread in chaffinches and also occurs, albeit less frequently, in greenfinches (Chloris chloris), goldfinches (Carduelis carduelis), bullfinches (Pyrrhula pyrrhula), rooks (Corvus frugilegus), jackdaws (Corvus monedula) and carrion crows (Corvus corone) (Pennycott, 2016;Lawson et al, 2018a;). Whilst most cases in wild birds appear to be mild or moderate, it has been proposed that severe lesions may predispose individuals to predation, trauma or co-infection (Pence 2008;Lawson et al 2018a).…”

“…Both dunnocks were found in the winter, when southern England experiences an influx of chaffinches migrating from continental Europe (Wernham 2002). With knemidokoptosis being widespread among chaffinches in GB, and a peak of infection known to occur in the winter months, it is possible that this creates a greater biotic reservoir of infection, heightening the risk of interspecific spillover from chaffinches to other passerines (Lawson et al 2018a). This risk could be compounded by a concomitant increase in congregations of passerines using supplementary feeding stations during the winter months when natural food sources can be scarce (Lawson et al 2018b).…”

Christmas disease in a Hovawart family resembling human hemophilia B Leyden is caused by a single nucleotide deletion in a highly conserved transcription factor binding site of the F9 gene promoter

“…35 Total reads of 1,029,601,630 (#4; sequencing depth 51x) and 1,000,503,256 (#6; sequencing depth 50x) were obtained and mapped to the reference canine F9 gene (NC_006621.3, region 109,501,341 to 109,533,798; CanFam3.1) using DNASTAR Lasergene Genomics Suite SeqMan NGen 15.2.0 (130). [36][37][38][39][40] Targeted genotyping of the promoter deletion was done by polymerase chain reaction (PCR) amplification with primers cfa_F9_Ex1_F (5'-CCACTGAGGGAGATGGACAC-3') and cfa_F9_Ex1_R (5'-CCCACATGCTGACGACTAGA-3') resulting in a fragment of 328 bp (wildtype) or 327 bp (deletion) spanning the variant position. The resulting PCR products were either directly sequenced on an ABI 3730 Genetic Analyzer (Thermo Fisher Scientific, Basel, Switzerland) or genotypes were determined by restriction fragment length polymorphism analysis after cleavage with RsaI.…”