Debilitating parasitic disease confirmed in UK donkeys

Nottingham University scientists and The Donkey Sanctuary have partnered on a study published in Parasites and Vectors on equine besnoitiosis which is transmitted by the protozoan parasite Besnoitia bennetti. It presents as parasitic cysts on the skin, nostrils, eyes and ears. A donkey at The Donkey Sanctuary presented with similar cysts to B bennetti, and an initial study of that specimen promoted the identification and study of around 20 clinical cases between 2013 and 2019.

Associate professor of veterinary parasitology at the University of Nottingham and lead author of the study, Hany Elsheikha, said: “B bennetti can infect any members of the family Equidae so horses, donkeys, mules and zebras are susceptible to infection by this parasite. Cases reported in horses seem to be limited to certain countries, such as Mexico and France, and parts of Africa. But given the right conditions for transmission of infection and the presence of the parasites, horses in any country could be at a risk of becoming infected. There is no reason to believe that this parasitic disease we detected in donkeys at The Donkey Sanctuary will not continue to infect donkeys in other regions in the UK in the future.

Dr Elsheikha continued: “This finding is crucial, because now we know about the problem, and we should remain vigilant for the emergence of any new cases. We need to know the source of infection. Is it a wildlife, another domestic species or even an insect? It remains uncertain how the Besnoitia parasite entered the UK, because none of the donkeys surveyed had a travel history or were imported or rescued from abroad. A missing factor in the investigation we conducted, and in all previous investigations about this parasitic disease, is the route of transmission. This parasite must complete its development inside two different hosts, one of them is the donkey, commonly called the intermediate host, and the other that plays the role of the definitive host could be any animal species. Numerous vertebrate species may be involved in Besnoitia transmission to donkeys and finding out which animal is the definitive host and elucidating its role in the transmission of infection to donkeys is probably going to be a complex challenge.”