Experimenta l Transmission of Trichinella spiralis to Swine by Infected Rats

Abstract

The role of rats in the transmission of Trichinella spiralis to swine is controversial because some experimental investigations have failed to show that swine will eat rat carcasses. Confinement-reared, grain-fed hogs were offered fresh rat carcasses harboring varying densities of muscle larvae. In all trials, rat carcasses were readily eaten in part or in their entirety, usually within a few hours. At necropsy these hogs were infected with T. spiralis muscle larvae. Hogs ate rat carcasses whether their regular feed was withheld or not. The initial portions of the carcass eaten were the naso-frontal section of the head (NF) and the tail. The consistent ingestion of the NF, including the tongue and facial muscles, is of significance since larval densities are usually high in these particular muscles. We conclude that rats must be considered a potential source of infection to swine until sufficient detailed epizootiological investigations are carried out to determine their actual importance on the farm.