Location: Animal Parasitic Diseases LaboratoryTitle: In Romania, exposure to Toxoplasma gondii occurs twice as often in swine raised for familial consumption as in hunted wild boar, but occurs rarely if ever among fattening pigs raised in confinement Author
Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2013
Publication Date: 6/1/2013
Citation: Pastiu, A.I., Gyorke, A., Blaga, R., Mircean, V., Rosenthal, B.M., Cozma, V. 2013. In Romania, exposure to Toxoplasma gondii occurs twice as often in swine raised for familial consumption as in hunted wild boar, but occurs rarely if ever among fattening pigs raised in confinement. Parasitology Research. 112(6):2403-2407. Interpretive Summary: It is important to understand the magnitude of risk associated with alternative animal husbandry practices. For example, marked public health gains have been made by enforcing biosecurity on swine farms in the United States by safeguarding animals against exposure to parasites, acquired from contaminated food and water, that otherwise cause human illness. Toxoplasmosis is a disease, especially important for pregnant women and people with AIDS. One (of several) means of contracting this illness involves the consumption of inadequately cooked, contaminated meat. Pork is an important suspected source, and there is a need to better understand the food safety risk of alternative production practices. This study took advantage of the fact that starkly differing methods are used to produce pork in Romania. These include industrial facilities in which the herd is isolated from the external environment, but also include the widespread practice of families raising small numbers of ‘backyard pigs’ for familial consumption, and also the hunting of wild boar. In this study, samples of each type of swine were tested for antibodies signifying exposure to Toxoplasma gondii, the parasite that causes toxoplasmosis. Reassuringly, swine raised in captivity entirely lacked evidence of exposure. However, wild boar were shown to have substantial rates of exposure. Of note, pigs raised for familial consumption had even higher rates of infection than did wild boar, suggesting that the environment around rural homes (inhabited by cats, an important source of exposure) and/or the diet of such backyard pigs (which may include uncooked meat scraps), provide an especially conducive venue for the transmission of this parasite. Regional variation in transmission risk was noted, and a power analysis was performed in order to evaluate how much sampling, in the future, would be necessary and sufficient to obtain precise estimates of the risk associated with each way of raising pigs. As they stand, the current findings provide new and compelling evidence that transmission of this parasite to swine, and ensuing risk of human illness, is amplified by conditions prevalent surrounding rural households that raise swine for subsistence consumption. These results will interest veterinarians, epidemiologists, and food safety authorities concerned with improving the health of rural communities.
Technical Abstract: A wide range of swine husbandry practices prevail in Romania: pork for human consumption is derived from hunting wild boar, from household rearing of small numbers of backyard pigs, and from indoor, industrial production of swine raised in confinement indoors. Romania thus represents an instructive place for evaluating the influence of animal management on the exposure risk of the zoonotic parasite, Toxoplasma gondii. The fact that many Romanians eat uncooked or undercooked pork, especially when raised for household consumption, elevates the public health imperative to understand these risks. The aim of the study, therefore, was to evaluate the seroprevalence of Toxoplasma gondii in pigs and wild boars from Romania. During 2008 - 2010, we collected 3595 serum samples from pigs (fattening pigs, sows, backyard pigs) and 150 serum samples from wild boars. The sera were assayed by immunofluorescence antibody test (IFAT) (cut off 1:32) for antibodies against T. gondii. The overall seroprevalence of T. gondii infection was 23.1% (829/3595) in pigs and 16% (24/150) in wild boars. The seroprevalence was significantly higher (p<0.001) in backyard pigs (30.5%; 783/2564) than in sows (12.4%; 46/371) or fattening pigs (none of sera was positive). The management system (indoor pigs versus backyard pigs) represented the most important factor in the epidemiology of T. gondii infection. The proximity of backyard pigs to the definitive host of this parasite (cats), as well as their access to contaminated meat products, elevated their exposure risk well above that pigs raised in confinement, and even above that of wild boars inhabiting sylvatic environments.