Researchers Develop Saliva-Based Equine Tapeworm Test

Researchers Develop Saliva-Based Equine Tapeworm Test

Tapeworms can grow up to 8 centimeters (3 inches) long and 1.5 centimeter (2/3 inch) wide and can cause colic and significant damage to the intestinal mucosa.

Photo: Martin Krarup Nielsen, DVM, PhD, Dipl. ACVM

In the global fight against parasite resistance to deworming medications, a group of researchers in the United Kingdom has recently developed a more practical test for the equine tapeworm. Because tapeworm infections are difficult to detect in feces, veterinarians’ preferred testing method has been blood testing. But that could be changing. A new, reliable saliva test is now making its appearance on European markets and could be available in the United States in 2017, researchers said.

The new saliva test allows owners to take samples themselves, said Corrine Austin, PhD, of Austin Davis Biologics Ltd, in Great Addington, U.K. This could encourage the use of a targeted deworming program that can help prevent parasite resistance.

“A limited number of drugs are available for treating equine helminths (worms) and, with no new chemical classes (drugs) in development, care must be taken to preserve the efficacy of the currently effective anthelmintics,” Austin said. “The use of accurate diagnostic tests to detect tapeworm burdens and, hence, inform treatment, will reduce the use of anti-tapeworm anthelmintics. And that could therefore reduce the risk for resistance emergence.”

The level of resistance in tapeworms to current anthelmintics is unknown. “Although resistance has yet to be documented for tapeworms, the risk is significantly increased with continued ‘blanket’ use of anti-tapeworm anthelmintics,” said Austin.

That blanket use has been recommended, until recently, due to the difficulty of detecting tapeworm infections, which can be devastating to horse health. These flattened parasites, whose four suckers attach to the ileocecal junction and cecum within the intestines, can grow up to 8 centimeters (3 inches) long and 1.5 centimeter (2/3 inch) wide. They can cause significant damage to the intestinal mucosa, as well as severe colic.

Their threat to horse health is all the more reason to prevent drug resistance, as the drugs need to stay potent for the horses that need them most, the scientists reported in their recent study.

Austin and her colleagues began research for developing a saliva test in 2011. Two years later, they analyzed saliva and blood collected from more than 100 horses at a U.K. slaughterhouse. They then compared those results with the number of tapeworms present during a physical examination of the intestinal tract of the horses post-mortem.

They found that their saliva test (developed based on ELISA testing) was accurate in detecting tapeworm presence. It was also strongly consistent with the ELISA-based blood test’s results, she said.

“Our test was capable of identifying horses with one or more tapeworms present, with a sensitivity (correctly identified horses with tapeworm burdens) of 83% and specificity (correctly identified horses without tapeworm burdens) of 85%,” Austin said. “The majority of horses with one or more tapeworms at post-mortem were correctly identified by the test.”

What about the 17% that weren’t correctly identified as having a tapeworm burden?

“The remaining few (positive horses) diagnosed as negative had burdens of less than 20 tapeworms, which is not considered to be a pathogenic (disease-causing) burden by experts; this is similar to worm egg counts for strongyles, where less than 200 eggs per gram is considered acceptable.” Austin explained. “It means that this test can be relied upon to correctly identify the majority of horses with a moderate/high burden and correctly identify all horses with pathogenic burdens.”

While the test is currently available to owners in the U.K. and parts of Europe, Austin said her team is working to make saliva collection kits available to U.S. owners, as well. The goal, she said, is to have kits in U.S. markets in 2017.

“Horse owners will be able to purchase saliva collection kits through distributors and collect the saliva sample themselves, before sending the sample back to the distributors, who will arrange for samples to be shipped to the U.K. for testing in our high-throughput lab,” Austin said.

“It is easy to integrate tapeworm testing into worm control programs,” Austin told The Horse. “Test every six months at a time when routine deworming for tapeworms would normally be considered. The program should also include regular worm egg counts for strongyles and ascarids and a winter worming dose for encysted cyathostomin.”

In the U.K., many horse owners are already using the test in their targeted deworming programs, Austin said. “Current data from over 20,000 U.K. samples shows that three quarters of horses are diagnosed as low and do not require deworming, so that’s a large number of horses that are not receiving unnecessary drugs,” she said.

The study, “Validation of a novel saliva-based ELISA test for diagnosing tapeworm burden in horses,” was published in Veterinary Clinical Pathology

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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