Slaughter inspection
Many countries have approved methods for post-mortem
inspection of pork for trichinae. Since trichinae cysts within
the tissue cannot be seen by macroscopic examination, one of
several possible laboratory tests must be performed.
The oldest method, and one still frequently used, is the
compression method. Small pieces of pork collected from the
pillars (crus muscle) of the diaphragm, or alternative sites, are
compressed between two thick glass slides (a compressorium)
and examined microscopically. A minimum of one gram
should be examined. In practice, the compression method,
using the trichinoscope, has an approximate sensitivity of > 5
larvae per gram of tissue (2).
An improvement for direct testing of pork for trichinae is
provided by the digestion methods. Samples of tissue
collected from sites of parasite predilection are subjected to
digestion in acidified pepsin. Larvae, freed from their muscle
cell capsules, are recovered by a series of sedimentation steps,
then visualised and enumerated under a microscope.
Requirements for performing the digestion test are found in
the Directives of the European Economic Community (EEC)
(17, 18), in the United States Department of Agriculture
(USDA) Code of Federal Regulations (47), in the Office
International des Epizooties (OIE) Manual of Standards (22)
and various other publications.
Post-slaughter samples are taken from the pillars (crus
muscle) of the diaphragm or alternative sites including the