Thursday, June 25, 2020

Parasitic disease found in British donkeys

A chronic and potentially debilitating parasitic equine disease which causes cystic lesions in the skin and eyes, has been found in donkeys in the UK for the first time.
The study was carried out by experts from the University of Nottingham and the Donkey Sanctuary. A full report is published in the journal Parasites and Vectors.

Equine besnoitiosis is a disease of donkeys, horses, zebra and mules. Affected donkeys develop multiple nodules in the skin, over the nostrils, ears and face. Cases may show tiny cysts on the surface of the eye. Some infected animals remain otherwise healthy, while others become thin and debilitated. 

The condition has been identified in a growing number of countries. The USA, Africa, Spain, Belgium, Italy, and Portugal are among countries reporting cases in donkeys. In horses, it is found especially in the tropics.

The disease is caused by Besnoitia bennetti, a protozoan parasite whose life cycle is poorly understood. 

The first UK case was identified in 2013, when a donkey at the Donkey Sanctuary was presented with skin lumps. They were initially presumed to be sarcoids, but microscopic examination revealed the presence of cysts typical of those caused by Besnoitia bennetti, along with tissue changes associated with sarcoids.

This case triggered a collaboration between a team of clinicians from the Donkey Sanctuary and a veterinary parasitologist from the School of Veterinary Medicine and Science at the University of Nottingham. Since then 20 clinical cases of this emerging parasitic infection have been identified and studied.

Other than one donkey that had come from Ireland, none of the donkeys included in the study had been abroad.

Dr Rebekah Sullivan, co-author of the report and a vet at the Donkey Sanctuary, said: “Given the relative proximity to other European countries, where clinical besnoitiosis is apparent, our findings will inform British vets of the potential for this emerging disease so that they can better recognise the pattern of clinical signs during clinical examination.”

 “It is absolutely essential – particularly now – that vets in the UK learn more about besnoitiosis, so they can identify and protect donkeys potentially at risk” said Dr Hany Elsheikha, lead author of the study and Associate Professor of Parasitology at the University of Nottingham. “Knowledge obtained in this study should improve our response to this emerging parasitic disease in donkeys in the UK, especially with the few treatment options and the unknown routes of transmission.”

The research team also developed serological and molecular screening methods, which allow earlier diagnosis of the disease.

Gereon Schares from the Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Germany, and co-author of the report,  added: “This study is particularly important because by using a suite of molecular methods we were able to confirm for the first time in Europe that the parasite agent involved in these cases is specifically Besnoitia bennetti and infection can be shown by serological methods.”

The correct identification of Besnoitia cysts in skin biopsies taken from UK allows veterinarians to give a more accurate prognosis. 

“It can no longer be assumed that skin masses are either neoplastic in origin or inflammatory, such as eosinophilic granulomas, for example,” said George Paraschou, co-author and pathologist at the Donkey Sanctuary.

For more details, see:

First record of besnoitiosis caused by Besnoitia bennetti in donkeys from the UK
Hany M. Elsheikha, Gereon Schares, Georgios Paraschou, Rebekah Sullivan and Richard Fox
Parasites Vectors (2020) 13:279

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