New tests will help find effective drug therapies against dourine in horses


Researchers have developed laboratory tests that will allow mass screening of potential agents against an important parasitic venereal disease in horses.

Researchers from Japan and Mongolia focused their attention on dourine, also known as covering sickness.

Dourine is caused by the protozoan Trypanosoma equiperdum and is spread by sexual intercourse with an infected horse. The organism has developed complex mechanisms over time for prolonged survival in equines.

T. equiperdum is one of three known strains from the Trypanosoma family; along with T. evansi and T. brucei.

T. equiperdum is closely linked to T. evansi. The World Organisation for Animal Health (OIE) notes the challenges in isolating T. equiperdum, adding that most of the strains currently available in national veterinary diagnostic laboratories are related to T evansi.

Signs of dourine infection include include fever, eye problems, weight loss, anemia, skin lesions and, in some cases, neurological signs. Infected animals have swelling of their genitals and will likely discharge pus. Up to 70% of infected horses die, but donkeys and mules are more resistant.

The clinical signs of infection can be treated but there is no cure and animals can be become carriers. Because of this, confirmed cases are euthanized in most countries.

Keisuke Suganuma and his colleagues, writing in the International Journal for Parasitology: Drugs and Drug Resistance, noted that although dourine had wide global distribution and was listed as an internationally important animal disease by the OIE, no effective treatment strategies had been established.

There were no reports on drug discoveries in tackling infections because no drug screening system existed for the parasite. A laboratory drug screening test for T. equiperdum was needed as part of efforts to seek new compounds to tackle infections and hopefully establish effective treatments.

They said a new T. equiperdum strain was recently isolated from a stallion that showed typical symptoms of dourine.

The study team described their development of two drug screening systems for T. equiperdum.

The luciferase test they developed would be suitable for the mass screening of chemical libraries against T. equiperdum because it allowed for the simple and rapid evaluation of the activities of test compounds, while their simple and inexpensive colorimetric test will be useful in developing countries for the evaluation of the drug sensitivity of epidemic trypanosome strains.

The establishment of in vitro culture and drug screening systems for a newly isolated strain of Trypanosoma equiperdum
Keisuke Suganuma, Shino Yamasaki, .Nthatisi Innocentia Molefeb, Peter Simon Musinguzib, Batdorj Davaasuren, Ehab Mossaad, Sandagdorj Narantsatsral, Banzragch Battur, Badgar Battsetseg and Noboru Inoue.

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

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