WESTERN STATES — New data shows tapeworm prevalence on West Coast farms as 17.3 percent in California, 36.5 percent in Oregon and 25.3 percent in Washington. A 2003 study in equine parasitology by Craig Reinemeyer, DVM, PhD, of East Tennessee Clinical Research, uncovered the high prevalence of equine tapeworms throughout the entire United States.

That original study indicated a lower risk of tapeworm exposure on the Pacific Coast compared to other areas. To get a better representation of the prevalence of tapeworm exposure, the study was recently repeated, using more than 300 farms and 600 samples from across Western states.

Research suggests that oribatid mites may be the key link to the tapeworm threat. As the intermediate hosts to Anoplocephala perfoliata, the most common species of tapeworm infecting U.S. horses. Any horse that grazes on pastures, eats hay, or is bedded with straw or wood products is likely exposed to oribatid mites, which could translate into tapeworm infections. The digested mites release the cysticercoids in the horse’s intestinal tract and the immature parasites then develop into adult tapeworms that attach to the ileocecal junction–the meeting place of the small intestine and the cecum. Horse owners can ensure their herd is protected by incorporating a praziquantel dewormer into their deworming program.