Researchers detect low Toxoplasma risk from cured meat products

Two studies have been published looking at Toxoplasma in Spanish dry-cured meat products and in meat of adult sheep.

Toxoplasmosis is an infection caused by Toxoplasma gondii. Transmission has been attributed to eating undercooked or raw meat.

In the first study, published in the journal Food Control, 552 samples of commercial dry-cured hams, shoulders and dry-cured sausages of different brands from different parts in Spain were purchased for analysis. These were 311 dry-cured hams/shoulders and 241 dry-cured sausages, including samples of chorizo, fuet/longaniza, and salchichón. Dry-cured meats are ready-to-eat (RTE) products and can be consumed without prior cooking.

Information on labels of each meat product were gathered to study the influence of curing time and salt content, among other parameters, on the viability of Toxoplasma. The parasite’s loss of viability in dry-cured meat products is dependent on factors such as curing time, salt content, water activity, pH, and fat content.

Viable parasite detection
Presence of Toxoplasma gondii was detected in 57 samples. A Bioassay test showed that 47 of these items produced mice seropositive response. Of those samples, DNA of Toxoplasma gondii in mice brain was detected in six meat products, indicating its viability.

The parasite was viable in three dry-cured ham/shoulder samples and three salchichón samples. All three samples of hams and shoulders in which Toxoplasma was viable came from white pigs, with curing times not exceeding 12 months.

All samples, except one, in which the parasite was viable, were commercially available packaged slices. Although no information was available on the label, it is a customary practice to previously freeze the entire piece to facilitate the slicing process. If this procedure was applied, it was not sufficient to kill the parasite and eliminate the risk, said scientists.

Statistical analysis showed that none of the variables under consideration on meat product labels had a significant influence on viability of the parasite.

Results indicate a low prevalence of infective forms of the parasite in cured meat products. However, some level of risk remains because of the inability of current meat inspection procedures at slaughterhouse to detect the parasite, and the curing process not always being effective. 

Scientists said monitoring of commercial meat products was necessary to provide data for risk assessments.

“In order to ensure that consumers can make a safe choice among these ready-to-eat products, it is important for food labels to include information on those parameters which are relevant for the survival of the parasite, such as curing times, or freezing treatment of meat used as an ingredient,” scientists said.

Second study on mutton
In the second study, published in the journal Food and Waterborne Parasitology, researchers evaluated Toxoplasma gondii in sheep meat.

A total of 216 muscle samples were analyzed and the prevalence of Toxoplasma gondii was 24.5 percent with 53 positive samples.

Samples came from the carcasses of female adult sheep slaughtered at an abattoir in Tomelloso in Castilla-La Mancha. They were collected by an official veterinarian twice a week at different times between May 2019 and February 2020.

The method used demonstrated Toxoplasma gondii DNA but not the presence of viable parasites capable of triggering a human infection.

“This study confirms the presence of Toxoplasma gondii DNA in mutton for the first time in Spain. These results should encourage researchers to investigate the presence and viability of Toxoplasma gondii in lambs, aiming to assess the actual risk of infection for the Spanish human population,” said scientists.

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