PRACTICAL AND EFFECTIVE ERADICATION OF PINWORMS (SYPHACIA-MURIS) IN RATS BY USE OF FENBENDAZOLE

Oxyurid parasites are common contaminants of laboratory rodents, and d espite many described treatments, no method has assumed preeminence. L imitations in drug efficacy and the general inability to control for e xposure to infective eggs are the primary contributors to treatment fa ilure. In addition, some effective drugs must be eliminated from consi deration because of narrow safety margins, other toxic aspects, or con cerns related to particular uses of the experimental animals. As an al ternative to currently described treatments or surgical derivation, we conducted an efficacy study against Syphacia muris in rats with a new fenbendazole-based protocol. Fenbendazole is a highly efficacious bro ad-spectrum anthelmintic with adulticidal, larvicidal, and ovicidal ac tions. Its pharmacokinetic behavior, ovicidal activity, and exceptiona lly wide safety margin in rats and mice make it an attractive choice f or pinworm treatment. We used a 150-ppm medicated feed formulation to reach a targeted dose of 8.0 to 12.0 mg/kg/day in three separate studi es designed to assess drug intake and efficacy under different housing conditions and in breeding and nonbreeding populations of ACI rats. I n all cases, drug was given on alternating weeks, and nonbreeding popu lations were medicated for a cumulative period of 14 days. The same sc hedule was used for breeding populations, but the treatment was repeat ed after a 2-week rest period to ensure sufficient exposure for newly weaned animals. The results of our study indicate that our described t reatment, in combination with environmental control measures against p inworm eggs, is capable of eliminating S. muris.