University of Medical Science Universidad de Ciencias Médicas (UCIMED), San José, Costa Rica, Central America. chinchillacm@ucimed.com

Support Sources: UCIMED, MICIT, CONICIT.

Results

Of the 100 CIA tests, 50 were from meat and 50 from chorizo, 4 of each groups were positive. From these eight samples, two from each product were confirmed with Sabin-Feldman test. This data indicated a positivity percentage of 4% for each meat product studied (Table 1). To the same samples studied with CIA tests, we performed the Sabin-Feldman test (dilutions of 1:2 to 1:16), where only 4 of the 8 samples were tested positive.

Looking at table 2, we can appreciate that the majority of the analyzed samples of both, meat and chorizo, came from independent establishments. Also, the positive ones with Sabin-Feldman confirmatory test came from the same type of establishments.

In relation with the histological analysis of the tested animals’ organs, a direct evidence of infection for T. gondii was not found, however it is important to emphasize that the reviewed 6 sections from each animal brain were also negative.

In table 3, some additional data is added, according to the place’s hygiene where the samples were collected. As it can be seen, from the 50 meat samples analyzed, 48% of the establishment had a good appearance and all were kept cooling chambers; on the contrary, chorizo samples from 54% of the establishments looked in fair or bad conditions. Furthermore, only 32 of 50 establishments conserved the products in cooling chambers, which leads to the presence of flies in a greater degree than with meat.

Discussion

The original concept for T. gondii transmission involved the ingestion of meat products as the main system, especially since Jacobs¹⁷ demonstrated the presence of the parasite in hamburgers. Subsequently and following the elucidation of Toxoplasma life cycle, in which it was determined that one of the developmental stages is the oocyst that is eliminated in the feces of cats;^{18, 19} it was considerate that the ingestion of the oocysts from the ground, were another route of ingestion in the human being. Such hypothesis were postulated in Costa Rica in very complete epidemiological studies were meat products were not taken into consideration as a source of infection.^9,10 Rather, it was implied that the ingestion of this parasite oocysts, were the most important system of infection for the human being. However, in latter studies, the presence of T. gondii in meat and pork was confirmed,^20,21 opening the possibility for these foods as another important source of infection.

These findings, plus others found positive for the presence of this parasite in certain type of sausages, induced studies to be performed, in relation of the prevalence of toxoplasmosis in human beings with the ingestion of meat products.²² Knowing the presence of T. gondii oocysts on the ground, in relationtothegreaterorlesserpresenceofcats,thatdisseminate those stages on the ground, also Arias et al²² demonstrated that such prevalence was related always with the presence of meat and sausages ingestion, independently of the number of these felines.

All of above, lead to the confirmation of the new hypothesis proposed by the authors, of a new concept for the transmission of this parasitic infection in Costa Rica¹² were the ingestion of meat and some sausages acquired increasing importance in the transmission of toxoplasmosis. However, given the increase in the export of meat, it was establish a new and more strict control measures in the management of these and consequently of sausages.^{23, 24}

The findings informed in these recent studies, although scarce, related to the conditions of the places of collection, with them seems to be demonstrated that these measures have influenced, at least in part, in reducing the presence of T. gondii in those foods. In fact it took 100 samples, 50 of grounded meat and 50 of chorizo to find only 4% of positivity in each of the products studied. This contrasts markedly with similar studies in the past,^{13, 21} were positivity observed was greater (8-40%), even when obtained with a lower number of samples of 38 and 40, lower than the one used in this study.

Thanks: This work was sponsored by the Department of investigation and the Cathedra of Medical Parasitology of the University of Medical Sciences (Universidad de Ciencias Médicas – UCIMED), the Ministry of Science and Technology (Ministerio de Ciencia y Tecnología – MICIT) and CONICIT. The authors thanked Laura Valerio and José Bolaños for their technical assistance during the period of study.