Epidemiological evidence that garden birds are a source of human salmonellosis in England and Wales

The importance of wild bird populations as a reservoir of zoonotic pathogens is well established. Salmonellosis is a frequently diagnosed infectious cause of mortality of garden birds in England and Wales, predominantly caused by Salmonella enterica subspecies enterica serovar Typhimurium definitive phage types 40, 56(v) and 160. In Britain, these phage types are considered highly host-adapted with a high degree of genetic similarity amongst isolates, and in some instances are clonal. Pulsed field gel electrophoresis, however, demonstrated minimal variation amongst matched DT40 and DT56(v) isolates derived from passerine and human incidents of salmonellosis across England in 2000-2007. Also, during the period 1993-2012, similar temporal and spatial trends of infection with these S. Typhimurium phage types occurred in both the British garden bird and human populations; 1.6% of all S. Typhimurium (0.2% of all Salmonella) isolates from humans in England and Wales over the period 2000-2010. These findings support the hypothesis that garden birds act as the primary reservoir of infection for these zoonotic bacteria. Most passerine salmonellosis outbreaks identified occurred at and around feeding stations, which are likely sites of public exposure to sick or dead garden birds and their faeces. We, therefore, advise the public to practise routine personal hygiene measures when feeding wild birds and especially when handling sick wild birds

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

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.We thank the members of the public and BTO Garden BirdWatch participants who reported garden bird morbidity and mortality incidents and our colleagues, Katie Beckmann, Shaheed Macgregor, Ricardo Castro Cesar de Sa, Lydia Franklinos and Tim Hopkins from the Zoological Society of London; Kirsi Peck from the Royal Society for the Protection of Birds; BTO staff members in the Garden BirdWatch team; the staff at Abbey Veterinary Services and the Animal & Plant Health Agency (Daniel Hicks, Richard Irvine, Alejandro Núñez and Scott Reid) for their assistance with this investigation. This work was financially supported by the following organisations; Birdcare Standards Association, British Trust for Ornithology, British Veterinary Association Animal Welfare Foundation, CJ Wildbird Foods, Cranswick Pet Products, UK Department for the Environment Food & Rural Affairs and Welsh Government through the Animal & Plant Health Agency’s Diseases of Wildlife Scheme Scanning Surveillance Programme (Project ED1600), Esmée Fairbairn Foundation, Gardman Ltd, Institute of Zoology, Royal Society for the Protection of Birds and the Universities Federation for Animal Welfare. RAJW was supported by the Moncloa of Excellence PICATA programme and Crafoord Foundation Sweden (grant number 20160971). Molecular and sequencing costs were funded by the Spanish Ministry of Science and Innovation, (Ref: CGL2013-41642-P/BOS)

Combining host and vector data informs emergence and potential impact of an Usutu virus outbreak in UK wild birds

Following the first detection in the United Kingdom of Usutu virus (USUV) in wild birds in 2020, we undertook a multidisciplinary investigation that combined screening host and vector populations with interrogation of national citizen science monitoring datasets to assess the potential for population impacts on avian hosts. Pathological findings from six USUV-positive wild passerines were non-specific, highlighting the need for molecular and immunohistochemical examinations to confirm infection. Mosquito surveillance at the index site identified USUV RNA in Culex pipiens s.l. following the outbreak. Although the Eurasian blackbird (Turdus merula) is most frequently impacted by USUV in Europe, national syndromic surveillance failed to detect any increase in occurrence of clinical signs consistent with USUV infection in this species. Furthermore, there was no increase in recoveries of dead blackbirds marked by the national ringing scheme. However, there was regional clustering of blackbird disease incident reports centred near the index site in 2020 and a contemporaneous marked reduction in the frequency with which blackbirds were recorded in gardens in this area, consistent with a hypothesis of disease-mediated population decline. Combining results from multidisciplinary schemes, as we have done, in real-time offers a model for the detection and impact assessment of future disease emergence events

Emerging Infectious Disease leads to Rapid Population Decline of Common British Birds

Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period

A clonal strain of Trichomonas gallinae is the aetiologic agent of an emerging avian epidemic disease

Trichomonas gallinae is a protozoan parasite that is well characterised as a cause of trichomonosis in columbid and raptor species world-wide. The parasite emerged as a novel infection of British passerines in 2005, leading to epidemic mortality associated with significant declines of breeding populations of greenfinches (Carduelis chloris) and chaffinches (Fringilla coelebs). We characterised the extent of T. gallinae genotypic heterogeneity within the affected wild British avifauna by analysing individual isolates from 17 of the species affected. To do so, we employed improved platform-based multilocus typing tools as well as the hydrogenosomal Fe-hydrogenase gene as a single marker locus for fine-typing. We found no evidence of heterogeneity amongst the parasites infecting British passerines, indicating that a clonal strain of T. gallinae is the causative agent of this emerging infectious disease

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

This work was financially supported by the following organisations; Birdcare Standards Association, British Trust for Ornithology, British Veterinary Association Animal Welfare Foundation, CJ Wildbird Foods, Cranswick Pet Products, UK Department for the Environment Food & Rural Affairs and Welsh Government through the Animal & Plant Health Agency’s Diseases of Wildlife Scheme Scanning Surveillance Programme (Project ED1600), Esmée Fairbairn Foundation, Gardman Ltd, Institute of Zoology, Royal Society for the Protection of Birds and the Universities Federation for Animal Welfare. RAJW was supported by the Moncloa of Excellence PICATA programme and Crafoord Foundation Sweden (grant number 20160971). Molecular and sequencing costs were funded by the Spanish Ministry of Science and Innovation, (Ref: CGL2013-41642-P/BOS).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.Depto. de Genética, Fisiología y MicrobiologíaFac. de Ciencias BiológicasTRUEpu