Eradication of Syphacia muris from food-restricted rats without environmental decontamination.

Rodent pinworms rarely cause clinical disease, but infestation can affect experimental results. Our facility maintained a colony of Wistar rats for behavioral pharmacology studies that had been infested with Syphacia muris for > 15 years. The laboratory in which the animals were housed encompassed several rooms and contained a variety of complex behavioral equipment, including > 60 operant chambers. Several prior attempts to eliminate the pinworms were unsuccessful because of inadequate duration of treatment and incomplete environmental decontamination. Many of the rats in this colony were food-restricted as part of behavioral studies. Pinworms were eliminated from these animals by treating them with 450 ppm fenbendazole-containing feed for 3 consecutive weeks followed by 6 weeks of alternating every other week with standard rodent diet. Rats not on food restriction protocols were treated on the same schedule with 150 ppm fenbendazole-containing feed. Environmental decontamination of eggs from the behavioral equipment was not attempted. One year after treatment, the colony has remained free of S. muris. We adapted previously published protocols to our situation, including the problem of food-restricted rats and unfeasible environmental decontamination, to eradicate S. muris from our colony.