DEVELOPMENT OF AN INTEGRATED RISK MODEL FOR FOODBORNE ZOONOTIC PARASITES IN SWINE
Title: Seroprevalence of Toxoplasma gondii in the U.S. swine herd using sera collected during the National Animal Health Monitoring Survey (Swine 2006)
Submitted to: Zoonoses and Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 27, 2008
Publication Date: February 10, 2010
Citation: Hill, D.E., Haley, C.A., Wineland, N., Gamble, H.R., Dubey, J.P. 2010. Seroprevalence of Toxoplasma gondii in the U.S. swine herd using sera collected during the National Animal Health Monitoring Survey (Swine 2006). Zoonoses and Public Health. 57:53-59.
Interpretive Summary: The United States Department of Agriculture (USDA) initiated the National Animal Health Monitoring System (NAHMS) in 1983 to collect, analyze, and disseminate data on animal health, management, and productivity in U.S. domestic livestock populations, including swine. The program includes an on-farm serological sampling component which can be used to monitor seroprevalence of various pathogens, including Toxoplasma gondii. The purpose of this study was to determine the seroprevalence of Toxoplasma gondii in grower/finisher pigs using sera collected during NAHMS 2006 and to compare the results with those from the 1995 and 2000 grower/finisher swine studies.
Sera and data on swine management practices was collected during the voluntary survey of 185 grower/finisher swine production sites located in 16 states accounting for >90% of U.S. swine production . A total of 6,238 sera were tested for T. gondii antibodies using a commercial ELISA assay; all positive sera were retested by ELISA and by the modified agglutination test (MAT). Seroprevalence, as determined by ELISA, was 2.65%, with a herd prevalence of 21.6%, and a mean within herd prevalence of 12.45%. Analysis of swine management practices indicated that rodent control methods, carcass disposal methods, and confinement rearing were associated with T. gondii positive farm status. These results are consistent with current epidemiological knowledge of the transmission of Toxoplasma on the farm (ingestion of organic matter containing oocysts, or ingestion of infected animal tissues). Production practices which eliminate these sources of exposure can reduce the risk of Toxoplasma infection in confinement reared pigs, and reduce the likelihood of human infection from consumption of infected pork.