Scared of trichinosis? Check with ELISA.

Scared of trichinosis? Check with ELISA 

According to the Centers for Disease Control in Atlanta, trichinosis is still a public health hazard. Between 1983 and 1985, at least 152 people in the United States contracted the disease; one died. But a quick blood test, just approved for commercial use, can identify which pigs contain the parasitic trichina worm. For states that choose, as Illinois has just started this year, to control trichinosis by culling contaminated animals prior to slaughter, it identifies infected pigs. Ultimately, it is envisioned as a screening test for use by slaughterhouse inspectors. The meat of animals whose blood passed the test could carry a seal certifying that it was trichina-free.

The test, an enzyme-linked immunosorbent assay (ELISA), looks for an antibody reaction to the trichina worm. A protein antigen from the worm is attached to a plastic surface. Then a blood sample is placed in contact with the antigen. If the animal is infected with the worm, a trichina antibody in its blood will stick to the antigen. After the blood is washed away, an enzyme is added that adheres only to the pig's antibody. The amount of enzyme that adheres--measured by how yellow the substrate gets--shows the level of any trichina infection. Though the whole procedure takes an hour, automation allows on-site processing of as many as 800 to 1,000 blood tests per hour at an average cost of about a penny per pound of meat involved, according to Diane Oliver, president of Idetek, the San Bruno, Calif., firm that has just begun marketing the test.

Even if trichina can be eliminated from some pork, what about Toxoplasma gondii, a potentially more serious parasite present in some pork (SN:7/19/86, p.37)? Toxoplasmosis concern "is a valid one,' Oliver says. However, she adds, "by eliminating trichina you tend to eliminate toxoplasma, since the same poor management practices--harboring rats, feeding pigs garbage and permitting them to eat other pigs that have died in the same pen--tend to foster both parasite infestations in herds. Moreover, she notes, her ELISA can be adapted to test simultaneously for other pathogens or meat contaminants like antibiotic residues. In preliminary tests looking for toxoplasma, she says, the ELISA "worked very well.'