Evaluation of Commercial Serological ELISA Kits for the Detection of Toxoplasma gondii Antibodies in Meat Juice of Pig

Introduction: Toxoplasma gondii is considered as one of the most important biological hazards in the context of meat inspection of pig according to the European Food Safety Authority (EFSA). Meat juice serology at slaughter can be used as a tool for targeting measures to control Toxoplasma gondii in pork.

Purpose: The purpose of the study was to evaluate four different commercial enzyme-linked immunosorbent assays (ELISA) for detection of antibodies against Toxoplasma gondii in meat juice samples from 90 naturally exposed slaughter pigs.

Methods: Meat samples (about 10 g of muscle from the diaphragm) from 90 slaughter pigs were collected. Samples were analyzed for Toxoplasma gondii antibodies using modified agglutination test (MAT) and four commercial ELISA kits. The results from the meat juice samples tested with the ELISA kits were evaluated against the results obtained with the MAT, which was considered as a reference method.

Results: Differences in the sensitivity (Sn), specificity (Sp) and accuracy (Ac) between the ELISA kits were detected and results were dependent on the cut-off level used: ELISA I with cut-off value 0.15: Sn 93.4 %, Sp 74.7 %, Ac 80.7 %; ELISA I with cut-off value 0.2: Sn 92.4 %, Sp 86.3 %, Ac 88.2 %; ELISA II: Sn 86.4 %, Sp 99.1 %, Ac 94.4 %; ELISA III: Sn 71.2 %, Sp 93.7 %, Ac 85.3 %; ELISA IV: Sn 3.6 %, Sp 100 %, Ac 70%.

Significance: The differences between ELISA I, II and III are mainly resulting from different cut-off values provided by the manufacturers, otherwise they seem to detect Toxoplasma gondii antibodies in meat juice samples from naturally infected finishing pigs comparably. The sensitivity of the ELISA IV was poor and further testing on meat juice from naturally infected animals is required.