The first isolation and molecular characterization of Toxoplasma gondii from horses in Serbia

Abstract

BackgroundConsumption of undercooked or insufficiently cured meat is a major risk factor for human infection with Toxoplasma gondii. Although horsemeat is typically consumed rare or undercooked, information on the risk of T. gondii from infected horse meat to humans is scarce. Here, we present the results of a study to determine the presence of T. gondii infection in slaughter horses in Serbia, and to attempt to isolate viable parasites.MethodsThe study included horses from all regions of Serbia slaughtered at two abattoirs between June 2013 and June 2015. Blood sera were tested for the presence of specific IgG T. gondii antibodies by the modified agglutination test (MAT), and samples of trypsin-digested heart tissue were bioassayed in mice. Cyst-positive mouse brain homogenates were subjected to DNA extraction and T. gondii strains were genotyped using 15 microsatellite markers (MS).ResultsA total of 105 slaughter horses were sampled. At the 1:6 cut-off 48.6% of the examined horses were seropositive, with the highest titre being 1:400. Viable parasites were isolated from two grade type mares; both parasite isolates (RS-Eq39 and RS-Eq40) were T. gondii type III, and both displayed an increased lethality for mice with successive passages. These are the first cases of isolation of T. gondii from horses in Serbia. When compared with a worldwide collection of 61 type III and type III-like strains, isolate RS-Eq39 showed a combination of MS lengths similar to a strain isolated from a duck in Iran, and isolate RS-Eq40 was identical in all markers to three strains isolated from a goat from Gabon, a sheep from France and a pig from Portugal. Interestingly, the source horses were one seronegative and one weakly seropositive.ConclusionsThe isolation of viable T. gondii parasites from slaughter horses points to horsemeat as a potential source of human infection, but the fact that viable parasites were isolated from horses with only a serological trace of T. gondii infection presents further evidence that serology may not be adequate to assess the risk of toxoplasmosis from horsemeat consumption. Presence of T. gondii type III in Serbia sheds more light into the potential origin of this archetypal lineage in Europe.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2104-x) contains supplementary material, which is available to authorized users.

Parasitic diseases of equids in Iran (1931–2020): a literature review

“…In that work, 2 of 126 horses (1.6%) tested positive [ 62 ]. Accordingly, eating raw horse meat may expose consumers to T. gondii [ 63 ] with severe cases of human toxoplasmosis reported in France due to the consumption of imported South American and North American horsemeat contaminated with highly pathogenic strains of the parasite [ 64 ]. However, as meat of equids is not consumed in Iran because of cultural and religious beliefs, horses and donkeys might not play a significant role in the epidemiology of human infections in the country.…”

Toxoplasma gondii genotypes circulating in domestic pigs in Serbia

“…Using the conventional PCR-RFLP method and a set of six genetic markers (SAG1, 5'SAG2, 3'SAG2, GRA6, 5'GRA7 and 3'GRA7), two pigeon isolates, as well as one sheep isolate, were classified as type II, whereas one pigeon isolate was identified as type III (Marković et al, 2014). Type III has recently also been detected in tissues of two slaughter horses, using microsatellite analysis with 15 markers (Klun et al, 2017). The detection of type III isolates in two pigs in this study supports earlier findings of a greater representation of type III in the countries of Southern Europe (De Dubey et al, 2006;Vergara et al, 2018).…”

“…through bird migrations, transportation and trade of animals and goods etc.) of type III from Africa and/or other countries in which this type is frequent (Mercier et al, 2010;Shwab et al, 2014;Klun et al, 2017).…”

“…In Serbia, most isolates obtained from human samples have been identified as type II, but one atypical strain has been detected (Djurković-Djaković et al, 2006;Štajner et al, 2013). In animals, genotyping of T. gondii strains isolated from pigeons, sheep and horses revealed both type II (pigeons and sheep) and type III (pigeons and horses) (Marković et al, 2014;Klun et al, 2017). In this paper, we present the first data on the T. gondii genotypes in pigs from Serbia.…”

Serological and Molecular Diagnosis of Toxoplasma Gondii Among Ewes and Horses in Duhok Province-Iraq

“…Due to the special relationship between horses and humans, Toxoplasma gondii could transmit from horse to humans. In some countries consumption of horse meat is common, so that due to eating of meat of the horse some cases of toxoplasmosis have been recorded (10,28).…”