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Toxoplasmosis has been recognized as a major public health problem worldwide. The consumption of uncooked or undercooked meat infected with Toxoplasma gondiitissue cysts is one of the main means of transmission of this parasite. Although sheep, goats, and pigs are commonly infected with T. gondii,little information is available on the distribution of T. gondiitissue cysts in naturally infected meat. In this study, we investigated the distribution of viable T. gondiitissue cysts in shoulder muscles of naturally infected lambs and goats. Hearts and shoulders of 46 lambs and 39 goats from a local grocery store were tested for T. gondiiinfection. Animals were evaluated for the presence of anti–T. gondiiantibodies in heart blood and clots by the modified agglutination test. Fourteen of the 85 animals (seven lambs and seven goats) were seropositive. Six to 12 samples weighing 5, 10, and 50 g were obtained from shoulder muscles of each seropositive animal and used for bioassay in mice. The distribution of viable T. gondiidiffered according to the size of the sample analyzed, but in general larger sample sizes resulted in higher isolation rates (P< 0.05). Results of the study revealed an uneven distribution of T. gondiiin muscle samples of lambs and goats and that T. gondiican be transmitted by consumption of very small servings (5 and 10 g) of meat when it is consumed raw or is undercooked.

Foodborne pathogens continue to pose a public health risk and can cause serious illness and significant outbreaks of disease in consumers. Toxoplasmosis is a zoonotic disease that occurs worldwide and is caused by the protozoan parasite, Toxoplasma gondii. The consumption of raw or undercooked infected meat, including pork, that contains infectious stages of T. gondiihas been regarded as a major route of T. gondiitransmission to humans. Given the occasional presence of T. gondiiin pork meat, the frequent use of pork for products not intended to be cooked, such as dry-cured ham, presents a potential risk for its transmission to consumers. In this study, we investigated the viability of T. gondiiin dry-cured whole hams processed using methods that were previously required for treatment of hams to inactivate Trichinella spiralisin the U.S. Code of Federal Regulations (9 CFR 318.10) and are now described in guidance documents from the U.S. Food Safety and Inspection Service. Infected pork hams were salted and cured for 33 days at 3°C and 85% ± 5% relative humidity (RH) and then were dried for up to 12 months at 12°C and 67.5% ± 2.5% RH. Inactivation of T. gondiiwas assessed in mouse bioassays and, serologically, by the modified agglutination test (MAT). Results showed that T. gondiibradyzoites were inactivated during the salting and curing step (33 days); no viable T. gondiiwas detected in the mouse bioassay and no evidence of serological conversion was detected by MAT in any of the mice inoculated with any of the samples tested during the drying step over the 12 months of the experiment. These results demonstrated that the approved protocols for production of dry-cured hams validated herein can inactivate T. gondiiand lower the risk to consumers of this product.

Toxoplasma gondiiis a prevalent protozoan parasite worldwide. Human toxoplasmosis is responsible for considerable morbidity and mortality in the United States, and meat products have been identified as an important source of T. gondiiinfections in humans. The goal of this study was to develop a farm-to-table quantitative microbial risk assessment model to predict the public health burden in the United States associated with consumption of U.S. domestically produced lamb. T. gondiiprevalence in market lambs was pooled from the 2011 National Animal Health Monitoring System survey, and the concentration of the infectious life stage (bradyzoites) was calculated in the developed model. A log-linear regression and an exponential dose-response model were used to model the reduction of T. gondiiduring home cooking and to predict the probability of infection, respectively. The mean probability of infection per serving of lamb was estimated to be 1.5 cases per 100,000 servings, corresponding to ~6,300 new infections per year in the U.S. population. Based on the sensitivity analysis, we identified cooking as the most effective method to influence human health risk. This study provided a quantitative microbial risk assessment framework for T. gondiiinfection through consumption of lamb and quantified the infection risk and public health burden associated with lamb consumption.

Toxoplasma gondiiis a global protozoan parasite capable of infecting most warm-blooded animals. Although healthy adult humans generally have no symptoms, severe illness does occur in certain groups, including congenitally infected fetuses and newborns, immunocompromised individuals including transplant patients. Epidemiological studies have demonstrated that consumption of raw or undercooked meat products is one of the major sources of infection with T. gondii. The goal of this study was to develop a framework to qualitatively estimate the exposure risk to T. gondiifrom various meat products consumed in the United States. Risk estimates of various meats were analyzed by a farm-to-retail qualitative assessment that included evaluation of farm, abattoir, storage and transportation, meat processing, packaging, and retail modules. It was found that exposure risks associated with meats from free-range chickens, nonconfinement-raised pigs, goats, and lamb are higher than those from confinement-raised pigs, cattle, and caged chickens. For fresh meat products, risk at the retail level was similar to that at the farm level unless meats had been frozen or moisture enhanced. Our results showed that meat processing, such as salting, freezing, commercial hot air drying, long fermentation times, hot smoking, and cooking, are able to reduce T. gondiilevels in meat products. whereas nitrite and/or nitrate, spice, low pH, and cold storage have no effect on the viability of T. gondiitissue cysts. Raw-fermented sausage, cured raw meat, meat that is not hot-air dried, and fresh processed meat were associated with higher exposure risks compared with cooked meat and frozen meat. This study provides a reference for meat management control programs to determine critical control points and serves as the foundation for future quantitative risk assessments.

Toxoplasma gondiiis a protozoan parasite that is responsible for approximately 24% of all estimated deaths attributed to foodborne pathogens in the United States. Human infection results from accidental ingestion of oocysts from the environment, in water, or on insufficiently washed produce or from consumption of raw or undercooked meat products that contain T. gondiitissue cysts. This review focused on studies of T. gondiiin meat because many human T. gondiiinfections are acquired through consumption of raw or undercooked meat. Prevalence of T. gondiiis higher in conventionally reared pigs, sheep, and poultry than in cattle and is greater in meat products from organic than from conventionally reared meat animals because of outdoor access, which poses substantially greater opportunities for exposure to infected rodents, wildlife, and oocyst-contaminated feed, water, or environmental surfaces. Risk factors related to T. gondiiexposure for livestock include farm type, feed source, presence of cats, methods of rodent and bird control, methods of carcass handling, and water quality. This review serves as a useful resource and information repository for informing quantitative risk assessment studies for T. gondiiinfection in humans through meat consumption.