Detection ofToxoplasma gondiiDNA in horse meat from supermarkets in France and performance evaluation of two serological tests

Abstract

In France, some cases of severe toxoplasmosis have been linked to the consumption of horse meat that had been imported from the American continent where atypical strains of Toxoplasma gondii are more common than in Europe. Many seroprevalence studies are presented in the literature but risk assessment of T. gondii infection after horse meat consumption is not possible in the absence of validated serological tests and the unknown correlation between detection of antibodies against T. gondii and presence of tissue cysts. We performed magnetic-capture polymerase chain reaction (MC-PCR) to detect T. gondii DNA in 231 horse meat samples purchased in supermarkets in France and evaluated the performance and level of agreement of the modified agglutination test (MAT) and enzyme-linked immunosorbent assay (ELISA) in the meat juices. The serological tests lacked sensitivity, specificity, and agreement between them, and there was no correlation with the presence of T. gondii DNA in horse meat, raising concerns about the reliability of T. gondii seroprevalence data in horses from the literature. T. gondii DNA was detected in 43% of horse meat samples but the absence of strain isolation in mice following inoculation of more than 100 horse meat samples suggests a low distribution of cysts in skeletal muscles and a low risk of T. gondii infection associated with horse meat consumption. However, to avoid any risk of toxoplasmosis, thorough cooking of horse meat is recommended.

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

“…in [29, 30]). Recent studies in Europe have shown seropositivity rates of 1.7% in Greece [31], 10.8% in Spain [32], 3% [33] and 17.6% in Italy [34], 23% in the Czech Republic [35], 37.8% in Romania [36], and from 13 to 90% (depending on the cut-off) in France [37]. It is difficult to assess whether the reported data represent real differences in the seroprevalence of T. gondii infection or possibly reflect the use of different assays, different cut-offs for modified agglutination assays or perhaps intrinsic differences in the study samples regarding age and/or true origin of the animals.…”

“…The risk was further emphasized by the isolation of a type III-like strain from horsemeat (originating from Canada) obtained from the first patient’s butcher [28]. Using MC-PCR, Aroussi et al [37] detected T. gondii DNA in 43% of 231 horsemeat samples from French supermarkets. Strain isolation was attempted from 118 samples by mouse bioassay, but no parasites were isolated, which the authors considered to reflect low distribution of cysts in skeletal muscles, therefore indicating a low risk of human T. gondii infection from consuming infected horsemeat [37].…”

“…Using MC-PCR, Aroussi et al [37] detected T. gondii DNA in 43% of 231 horsemeat samples from French supermarkets. Strain isolation was attempted from 118 samples by mouse bioassay, but no parasites were isolated, which the authors considered to reflect low distribution of cysts in skeletal muscles, therefore indicating a low risk of human T. gondii infection from consuming infected horsemeat [37]. However, quite the opposite was concluded in a study of the relative contribution of sheep, beef and pork products to human T. gondii infection in the Netherlands (as quantified by Quantitative Microbial Risk Assessment), which showed a high public health risk even in the case of low prevalence of parasite cysts in animal tissues, if the meat is inadequately processed [53].…”

“…However, a low cut-off of 1:10 was shown to give the best sensitivity/specificity balance between the MAT test and the presence of T. gondii DNA in meat samples as detected by MC-PCR [37]. Another important point is that the strains we isolated originated from one weakly seropositive animal and from another completely seronegative one.…”

Toxoplasma Serostatus in Thai Free- Range Chickens: Prevalence and Two Diagnostic Methods

“…Such as IFAT requires special equipment or appropriate anti-species serum. MAT is simple, easy to perform and does not require those [7], however, some articles seems to call into question the fact that this technique can be applied to all animal species [28]. In this study, both IFAT and MAT were used and able to detect T. gondii antibodies in all inoculated chickens.…”