Protozoan donkey infection in Europe: “Widespread distribution … would be of international concern”

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A histopathological preparation from the male donkey showing a cyst full of bradyzoites (encysted parasites). Photo: Liénard et al. https://doi.org/10.1186/s13071-018-2993-3
A histopathological preparation from the male donkey showing a cyst full of bradyzoites (encysted parasites). Photo: Liénard et al. https://doi.org/10.1186/s13071-018-2993-3

Vets in Europe should consider the possibility of besnoitiosis when tackling hard-to-treat dermatitis in donkeys, according to researchers, after confirming the first case in a jack in Belgium.

Besnoitiosis is caused by different species of intracellular protozoan parasites and can affect many species worldwide.

Ten species are known to infect animals, including Besnoitia bennetti, which has been found in horses, donkeys and zebras. It has been described in Africa and the United States, where donkey besnoitiosis is considered an emerging disease.

The Belgium case, described this week in the journal Parasites & Vectors, involved a two-year-old male donkey bought in May 2016 by its present owner from a milk-producing donkey farm in Frasnes-lez-Buissenal, Blegium.

Yannick Caron and his colleagues reported that the donkey had been purchased in poor body condition, with body wasting, bald areas and severe itching, mainly on the neck and head.

Shortly after its purchase and shearing, the donkey presented with crusts and skin thickening on its flanks and neck, as well as ongoing weight loss.

A treatment with phoxim was given with no improvement.

Further tests revealed a thick-walled cyst with evidence of parasite infection highly suggestive of besnoitiosis.

DNA-based testing confirmed infection with Besnoitia bennetti.

Pin-head sized cysts caused by the parasitic infection. Photo: Liénard et al. https://doi.org/10.1186/s13071-018-2993-3
Pin-head sized cysts caused by the parasitic infection. Photo: Liénard et al.  https://doi.org/10.1186/s13071-018-2993-3

Another ten-year-old female donkey purchased in France and sharing the same accommodation showed good clinical condition, but a thorough clinical examination showed the presence of many cysts on the inner face of upper labial mucosa.

Testing for B. bennetti was negative, but the presence of antibodies directed to Besnoitia species were detected.

The case of the male is the first unequivocal report of B. bennetti infection in donkeys in Europe, the study team said, based on clinical, histological, serological and molecular tools.

“Difficulties in confirming diagnoses and the absence of efficient treatment options are probably responsible for the under-reporting of besnoitiosis in European donkeys,” they said.

“This report aimed to highlight to clinicians the necessity to include besnoitiosis in the differential diagnosis of chronic dermatitis unresponsive to routine topical and systemic treatments.”

They continued: “Whether this finding represents an unusual cluster of infections or reflects a wider distribution of subclinical infections which have largely gone undetected to date requires further study.

“Donkeys are increasing in number and particularly in developing countries.

“Widespread distribution of this infection would be of international concern and veterinary medical importance.

“Further investigations are necessary to unravel the phylogeny (evolution) of B. bennetti and its epidemiology in Europe and elsewhere.”

First evidence of Besnoitia bennetti infection (Protozoa: Apicomplexa) in donkeys (Equus asinus) in Belgium
Emmanuel Liénard, Adriana Nabuco, Sophie Vandenabeele, Bertrand Losson, Irène Tosi, Émilie Bouhsira, Françoise Prévot, Shukri Sharif, Michel Franc, Caroline Vanvinckenroye and Yannick Caron.
Parasites & Vectors 2018 11:427 https://doi.org/10.1186/s13071-018-2993-3

The study, published under a Creative Commons License, can be read here.  

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