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Sheep and goats
High mortality in a sheep flock caused by coinfection of louping ill virus and Anaplasma phagocytophilum
  1. Roger Daniel1,
  2. Beverley Ann Mary Hopkins1,
  3. Mara S Rocchi2,
  4. Mark Wessels3 and
  5. Tobias Floyd4
  1. 1Wales Veterinary Science Centre, Aberystwyth, UK
  2. 2Virus Surveillance Unit, Moredun Research Institute, Penicuik, UK
  3. 3Histopathology, Finn Pathologists, Diss, UK
  4. 4Pathology, Animal and Plant Health Agency, Addlestone, UK
  1. Correspondence to Roger Daniel;{at}; Dr Beverley Ann Mary Hopkins; bevhopkins{at}


Fifty-three of a mixed flock of 180 one-year-old lambs (hoggs) and older, barren ewes (ewes that were non-pregnant or had not lambed that spring) died in May 2019 following introduction to 30 acres of unimproved hill pasture. The flock was moved onto this pasture in early May, and clinical signs and deaths were observed 14 days later. Clinical signs included dyspnoea, lethargy, and sternal and lateral recumbency; the majority were found dead. The flock was removed from the hill the day after the first deaths were discovered. Deaths continued for a further 14 days until a total of 53 animals had died. Three hoggs were submitted for postmortem examination to the Wales Veterinary Science Centre. Anaplasma phagocytophilum, the causal organism of tickborne fever, was detected by PCR testing. Coinfection with louping ill virus was also suspected and later confirmed. The laboratory findings are described, and the risk of these diseases to grazing sheep in upland areas is discussed, as well as the measures being taken to reduce the risk of infection.

  • tickborne diseases
  • histopathology
  • pathology
  • diagnostics
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  • Contributors RD carried out the postmortem examination and test selection, and drafted the majority of the manuscript. BAMH carried out multiple postmortem examinations, test selection and revision of the manuscript. MW carried out all histopathological investigations along with description of the histopathology within the manuscript. MSR led the laboratory testing for both LIV and TBF at Moredun Research Institute along with revision of the manuscript. TF carried out immunohistochemistry on the brains from two ewes and revision of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article.

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