Clinical and Serologic Features of Besnoitiosis in Donkeys in the Northeastern United States and Attempted Treatment of Two Cases

Donkeys affected by besnoitiosis have characteristic clinical lesions and high antibody titers to Besnoitia bennetti. Knowledge of these features may assist clinicians in the identification and diagnosis of besnoitiosis in donkeys. Ponazuril^a does not appear to be an effective treatment. Authors’ addresses: Department of Clinical Sciences (Ness, Divers), Department of Biomedical Sciences (Peters-Kennedy), Department of Population Medicine and Diagnostic Sciences (Mittel, Mohammed), and the Department of Microbiology and Immunology (Bowman, Felippe, Wade), College of Veterinary Medicine, Cornell University, Ithaca, NY 14853; Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Epidemiology, Seestrasse 55, D-16868 Wusterhausen, Germany (Schares); United States Department of Agriculture, Agricultural Research Service, Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, Beltsville, MD 20705 (Dubey); Benton, PA 17814 (Shultz); e-mail: [email protected].

1. Introduction

Besnoitia species are coccidian parasites that infect multiple host species worldwide.^1,2  Besnoitiosis has recently been diagnosed in numerous donkeys from several states on samples sent to Cornell University. We describe the clinical and serologic features of besnoitiosis in donkeys and investigate the utility of serology as a diagnostic screening test. The outcome of a treatment trial with ponazuril^a  in 2 naturally infected donkeys is reported.

2. Materials and Methods

Field Investigation

Donkeys from 3 northeastern herds were examined for external and nasopharyngeal endoscopic lesions consistent with besnoitiosis. IFAT and immunoblot for serum antibodies to B. bennetti were performed on all individuals. Histopathology was used to confirm infection.

Clinical Treatment Trial

Two naturally infected donkeys received a 37-day course of therapy with ponazuril. Response to treatment was assessed with weekly biopsies. 

3. Results

Field Investigation

Besnoitiosis was confirmed in several donkeys. External and endoscopic lesions were numerous in infected individuals. Infected individuals had significantly higher antibody titers to B. bennetti than did noninfected individuals.

Clinical Treatment Trial

No clinical or histological response to treatment was noted.

4. Discussion

Donkeys affected by besnoitiosis develop parasitic cysts in the skin, mucous membranes, sclera, and nasopharynx. Serology may be useful for identifying infected individuals. Ponazuril does not appear to be an effective treatment.

The authors thank Bayer Animal Health for providing Marquis^® for the treatment trial.

References and Footnote

1. Dubey JP, Sreekumar C, Donovan T, et al. Redescription of Besnoitia bennetti (Protozoa: Apicomplexa) from the donkey (Equus asinus). Int J Parasitol 2005;35:659–672.
2. Dubey JP, Yabsley MJ. Besnoitia neotomofelis n. sp. (Protozoa: Apicomplexa) from the southern plains woodrat (Neotoma micropus). Parasitology 2010;137:1731–1747.

^a Marquis^®, Bayer Animal Health, Shawnee Mission, KS 66201.