Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 25, 1998
Publication Date: N/A
Interpretive Summary: The protozoan parasite Toxoplasma gondii is known to cause birth defects in infants and death in the immunocompromised. Approximately 40% of the U.S. population has antibodies to this parasite, indicating prior exposure. Although infective stages passed in the feces of cats are known to be a major source of human infection, recent evidence suggests meat infected with a cyst stage also causes infection in man. The prevalence of T. gondii in pigs has been studied on a regional and national level. In this study, we have targeted small farms in five New England states to determine parasite prevalence and risks associated with pig infection. Pigs in these state had an infection rate of almost 50%, which is 2-10 times the national average. All farms tested used management practices which were consistent with known risk factors for exposure to T. gondii.
To determine regional prevalence of infection with Toxoplasma gondii, 1897 pigs from 85 farms in five New England states were tested using a modified agglutination test. Farm management questionnaires were completed at the time of blood collection and were used to develop descriptive statistics on farms tested and to determine measures of association for risk factors for the presence of T. gondii-seropositive pigs. A total of 900 positive pigs were identified for a prevalence rate of 47.4%. Of 85 herds tested, 77 had at least one positive pig for a herd prevalence rate of 90.6%. Within herd prevalence ranged from 4-100% (mean = 48.4%). All farms studied had one or more risk factors for exposure to T. gondii. However, statistical associations with individual risks could not be made, most likely due to the extremely high prevalence. The results obtained here suggest that education on farm management practices to reduce exposure to T. gondii should be targeted to include small producers.