Parasitic pneumonia in roe deer (Capreolus capreolus) in Cornwall, Great Britain, caused by Varestrongylus capreoli (Protostrongylidae).

Background: Roe deer (Capreolus capreolus) became extinct over large areas of Britain during the post mediaeval period but following re-introductions from Europe during the 1800s and early 1900s the population started to recover and in recent decades there has been a spectacular increase. Many roe deer are shot in Britain each year but despite this there is little published information on the diseases and causes of mortality of roe deer in Great Britain.

Case Presentation: The lungs of two hunter-shot roe deer in Cornwall showed multiple, raised, nodular lesions associated with numerous protostrongylid-type nematode eggs and first stage larvae. There was a pronounced inflammatory cell response (mostly macrophages, eosinophils and multinucleate giant cells) and smooth muscle hypertrophy of the smaller bronchioles. The morphology of the larvae was consistent with that of a Varestrongylus species and sequencing of an internal transcribed spacer-2 fragment confirmed 100% identity with a published Norwegian Varestrongylus cf. capreoli sequence. To the best of the authors' knowledge this is the first confirmed record of V. capreoli in Great Britain. Co-infection with an adult protostrongylid, identified by DNA sequencing as Varestrongylus sagittatus, was also demonstrated in one case.

Conclusions: Parasitic pneumonia is regarded as a common cause of mortality in roe deer and is typically attributed to infection with Dictyocaulus sp. This study has shown that Varestrongylus capreoli also has the capability to cause significant lung pathology in roe deer and heavy infection could be of clinical significance.