Toxoplasma gondii in Retail Beef,Lamb,and Pork in Canada: Prevalence,Quantification,and Risk Factors from a Public Health Perspective

Abstract

Toxoplasmosis is a zoonosis of public health concern worldwide. Toxoplasma gondii can be transmitted to humans through the consumption of raw or undercooked meat, but little is known about the risk associated with various meat commodities consumed by Canadians. We set out to estimate the prevalence and risk factors of T. gondii-positive status of retail meat in Canada using a combination of ELISA and quantitative polymerase chain reaction, and found a prevalence of 0.3% in pork (n = 360), 0.6% (n = 329) in beef, and between 4.3% and 11.1% in lamb (n = 298), depending on province. Most of (75%) positive lamb samples (100 g each) contained more than 4000 parasites, relative to the standard curve. Lamb had a higher risk (p < 0.001) of being T. gondii positive compared to beef and pork. Using multivariable logistic regression, T. gondii positivity in lamb samples was associated (p < 0.001) with “country of origin” and “meat cut,” but no association was detected regarding store location, store category (independent, chain or butcher), or store volume. Ground lamb was identified as a risk factor compared to any other cuts. Overall, 26.4% of New Zealand imported lamb was positive to T. gondii compared to 4.0% of Canadian meat and 4.1% of Australian meat; only the difference between New Zealand and Australia was statistically significant in the multivariable model (p < 0.001). However, considering the conditions under which it is transported, frozen New Zealand (and Australian) lamb should not present a risk to Canadian public health. These results provide critical information for performing T. gondii quantitative risk assessments in food and for orienting acquired and congenital toxoplasmosis prevention strategies by targeting potential transmission sources.