Detection of Viable Toxoplasma gondii in Free-Range Pigs from the Special Nature Reserve of Zasavica

Abstract

Toxoplasma gondii is considered one of the most successful parasites of humans and animals. The ingestion of viable cysts through the consumption of undercooked pork is recognized as a significant route of human infection with T. gondii. The aim of this study was to investigate the presence of viable parasite in tissues of free-range pigs from the Zasavica Special Nature Reserve. All pigs were of the Mangulica breed, raised in a traditional way. The serological screening was performed using a modified agglutination test (MAT). The isolation of viable T. gondii was attempted by a bioassay of pig heart tissue in mice, while the real-time polymerase chain reaction (qPCR) targeted at the 529 bp repetitive element of T. gondii was used to detect parasitic DNA in digested hearts. Specific antibodies were detected in 12 out of 18 pigs examined. The bioassay was performed for five MAT-positive and one MAT-negative pig, and a total of three isolates were obtained. qPCR was performed for all samples, including one MAT-negative sample that was not bioassayed. The presence of T. gondii DNA was confirmed in all hearts with a positive bioassay as well as in one originating from seropositive and one from seronegative pig whose hearts were not bioassayed. The successful isolation of viable cysts, presence of risk factors (such as older age at the time of slaughter) and increased contact with the environment, along with the great appreciation of Serbian consumers towards home-cured Mangulica's meat, make this breed worthy of consideration as a potentially important reservoir of human infection.

A Pork Industry in the Backyard: An Analysis of Toxoplasma gondii Infection in Serbia’s Pigs

“…The true prevalence of T. gondii infection in backyard pigs in Serbia is not known at present, but it stands to reason that it varies considerably among farms. An indicative value may be 66.7%, as reported in Mangulitsa pigs from the Zasavica reserve [47]. Mangulitsa is an indigenous breed that is produced extensively and traditionally reared outdoors year-round.…”

“…Mangulitsa is an indigenous breed that is produced extensively and traditionally reared outdoors year-round. Mangulitsa pigs are usually significantly older than fattened pigs at the time of slaughter, and their meat is often cured and/or fermented into various products, which have a delicatessen status in Serbia [ 44 , 47 ]. The largest Mangulitsa farm is family-owned and maintains up to 1000 animals on a 70-hectare homestead in a remote rural area [ 56 ], while the Mangulitsa of the Zasavica reserve are reared on a 300-hectare pasture [ 47 , 57 ].…”

“…Mangulitsa pigs are usually significantly older than fattened pigs at the time of slaughter, and their meat is often cured and/or fermented into various products, which have a delicatessen status in Serbia [ 44 , 47 ]. The largest Mangulitsa farm is family-owned and maintains up to 1000 animals on a 70-hectare homestead in a remote rural area [ 56 ], while the Mangulitsa of the Zasavica reserve are reared on a 300-hectare pasture [ 47 , 57 ]. As semi-feral pigs, Mangulitsa are essentially reared without any biosecurity and hygiene measures that could prevent T. gondii infections.…”

Toxoplasma gondii Infection in Pigs in Serbia

“…The cumulative seroprevalence of T gondii infection in Serbian pigs is 18.8%. The lowest seroprevalence of 9.2% was observed in market-weight pigs slaughtered in the Belgrade area abattoirs (Klun et al, 2011), and the highest, of 66.7%, in an outdoor herd of indigenous Mangulitsa breed pigs butchered at a private slaughterhouse (Kuruca et al, 2016). To date, 15 isolates have been obtained from pig tissues, and only two genotypes, archetype II (Tox-oDB#1) and archetype III (ToxoDB#2), have been identified (Kuruca et al, 2019;Uzelac et al, 2023).…”

Toxoplasma gondii genotypes circulating in domestic pigs in Serbia

“…Samples from 18 slaughter pigs in which either viable T. gondii or T. gondii DNA was detected by mouse bioassay and PCR, respectively (Kuruca et al, 2016(Kuruca et al, , 2017, were used for strain genotyping. All pigs originated from the territory of Northern Serbia and all but one were from Vojvodina province.…”