Detection of Trichinella infection in slaughter horses by ELISA and western blot analysis.

In order to determine the presence of Trichinella infections in horses slaughtered at an abattoir in Mexico, 147 serum samples were examined by two immunoenzymatic methods. Specific antibodies were detected by ELISA in 7% of the serum samples at a dilution 1:400 and in 10% at lower dilutions (1:20, 1:40) using Trichinella spiralis muscle larvae (ML) excretory/secretory (E/S) products. Serum samples from four naturally infected horses (confirmed by direct methods) gave negative O.D. values in an ELISA at a 1:400 dilution and only two of them were positive at a 1:20 and 1:40 dilutions. Serum samples from experimentally infected horses reacted by Western blotting with ML components with molecular weights of 47, 52, 59, 67, 72 and 105 kDa which correspond to the TSL-1 antigens. Serum samples from the four naturally infected horses and from the abattoir horses that were positive in ELISA using E/S antigens recognized several ML components, some of them reacted with all the TSL-1 antigens mentioned above and others recognized preferentially two or three of these molecules. Since the serologic assays may not offer the sensitivity required in the diagnosis of horses trichinellosis and the direct methods had not always been useful in the detection of larvae in horsemeat related to trichinellosis outbreaks in Europe, it is proposed that additional assays are performed to determine Trichinella infection in horses. These can include detection of parasite antigens by ELISA and Dot ELISA or PCR, which in turn may also help to determine the presence of the parasite in early and late infections of horses.