Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/2006
Publication Date: 6/1/2006
Citation: Hill, D.E., Sreekumar, C., Dubey, J.P., Lunney, J.K., Gamble, H.R. 2006. Comparison of detection methods for Toxoplasma gondii in naturally and experimentally infected swine. Veterinary Parasitology. 141:9-17.
Interpretive Summary: Results from the 6 assays used to detect Toxoplasma gondii in swine tissues indicate that cat bioassay is the most sensitive method for detecting T. gondii in swine tissue; even small numbers of parasites in meat samples are capable of infecting a cat which will produce millions of easily detectable oocysts as a result. In addition, large quantities of meat samples can be fed to a single cat, making detection of light infections more likely. Serological assays such as ELISA and MAT are capable of detecting greater than 90% of infected pigs when serum is tested, but only 50% when tissue fluids are tested. Use of PCR (direct, nested, or real time) to detect T. gondii DNA in tissues from naturally or experimentally infected pigs was the least reliable method used; the random nature of tissue cyst distribution in pork samples, the small quantities of each sample that can be analyzed, and the resulting potential for false-negative findings make the use of PCR currently impractical.
Technical Abstract: Results from recent serological surveys and epidemiological studies indicate that pigs raised in a variety of management systems can be carriers of the tissue cyst stage of Toxoplasma gondii, a protozoan parasite that frequently infects humans. The parasite can be transmitted to humans through the consumption of improperly prepared infected pork, making detection and removal of infected swine carcasses from the food chain an important food safety issue. Several detection methods are available for detection of Toxoplasma infected swine, including serological assays (ELISA and MAT), polymerase chain reaction (PCR), and animal bioassays. The aim of the present study was to compare the detection sensitivities of 6 of these commonly used methods for detection of Toxoplasma gondii infection in swine tissues from naturally and experimentally infected animals.