Serological survey of antibodies against Toxoplasma gondii and Neospora caninum in pigs from various regions of Poland.

Background: Pigs are prone to infections with several protozoa species. Although infection with Toxoplasma gondii rarely results in clinical symptoms in pigs, consuming pork-containing cysts represents a potential threat to human health, especially in immunocompromised individuals, pregnant women, and fetuses. It is estimated that around 2 billion people are infected with Toxoplasma gondii worldwide, making toxoplasmosis one of the most damaging zoonoses. Due to the coincidence of several factors, the meat from infected pigs can, however, frequently reach the consumer. In cattle, infection with Neospora caninum can cause considerable economic losses. The consequences of this infection for pigs remain unclear. However, infection in sows was linked with the development of some clinical signs, and transplacental transmission of the parasite was observed. Therefore, it should be considered a potential threat to pigs' health. Due to the above reasons, the data regarding the epidemiology of the mentioned parasites seems desirable. Since Poland represents one of the major pig producers in the European Union, and pork is the most commonly consumed type of meat, the present study aimed to determine the seroprevalence of Toxoplasma gondii and Neospora caninum in the Polish pig population. 1034 serum samples were collected from 16 commercial farms localised in 9 different provinces (voivodeships) of Poland from pigs belonging to the following age categories: piglets (259), weaners (220), fatteners (243), gilts (70), and sows (242) were subjected to ELISA assay with the use of commercially available kits.

Results: The overall seroprevalence of Toxoplasma gondii was 11.3% (117/1034), and it was significantly higher in sows compared to other age categories (28.1%; p < 0.05). Regarding the province of Poland, the highest proportion of seropositive pigs was found in Kujawsko-Pomorskie and Podlaskie; meanwhile, in Łódzkie, Pomorskie, and Warmińsko-Mazurskie observed seroprevalence was 0%. Among tested samples, only one (1/1034; 0.097%) was positive for Neospora caninum antibodies, and it was collected from gilt maintained on the farm in Zachodniopomorskie.

Conclusions: This study updates the data on Toxoplasma gondii epidemiology in pigs reared in Poland, showing relative stability in the infection with this parasite. It also provides the first data on Neospora caninum circulation in the Polish pig population.