Toxoplasma gondii in raw and dry-cured ham: The influence of the curing process

The aim of this work was to analyze Toxoplasma gondii in raw hams by mouse bioassay and to evaluate the effect of curing on the viability of the parasite to assess the risk of infection from eating dry-cured ham. After a serology study of 1200 pigs in Aragón (Spain), forty-one naturally infected pigs with different serological titers against T. gondii were selected. Two cured periods (9 and 12 months) were evaluated as well as the influence of the physicochemical composition of hams on T. gondii survival. Although the parasite burden was low, a high number of seropositive pigs with Toxoplasma tissues cysts in raw hams were found (31.6%). Viability of T. gondii was influenced by the curing, with statistically significant differences between fresh and cured hams (p < 0.001). The viability was higher in hams cured for 9 months compared to those cured for 12 months. However, this period of curing resulted in the reduction but not in a complete elimination of the risk. Thus, from a public health point of view, under the conditions of this study it is safer to consume dry-cured ham with periods of curing higher than 12 months. Analysis of physicochemical results did not identify any variable with significant influence on the presence and viability of T. gondii in cured ham, but loss of viability of T. gondii was observed in hams with a lower fat content. Further research is required to validate combinations of salts concentration and time of curing that can be used as preventive measures in the HACCP system of dry-cured ham industry.