Detection of Trichinella spiralis in a horse during routine examination in Italy.

The researchers identified the presence of a parasite known as Trichinella spiralis in one horse out of 28 imported from Romania to Italy. The detection was made during a routine examination. The study further observed the parasite’s reproductive capacity and morphology, and also did serological tests on other horses from the same stock.

Identification of Trichinella spiralis

• The researchers performed a routine examination for Trichinella infection in horses imported from Romania to an abattoir in Italy. This examination involved artificially digesting 5-gram samples of muscle tissue.
• In one of the 28 horses examined, they detected the presence of muscle larvae. This parasite was identified as Trichinella spiralis using polymerase chain reaction, a molecular biology technique used to amplify and therefore detect specific DNA sequences.

Characteristics and Reproductive Capacity of the Parasite

• The identified Trichinella spiralis parasite had a reproductive capacity index of 68 in Swiss mice, suggesting a higher rate of reproduction.
• Under light microscope examination, they observed 200 nurse cell-larva complexes. These are specific structures formed by the parasite in the host’s muscle tissue.
• Of these complexes, 22% were calcified, and the capsules of the non-calcified nurse cells had very few cellular infiltrates and were 17.5-27.5 microns thick.

Serological Tests and Previous Infection

• The team conducted serological tests, namely ELISA (enzyme-linked immunosorbent assay) and Western blot analyses, on serum samples from the horse with the parasitological positive result and three other horses from the same stock.
• Using a crude antigen, the tests showed a low level of positivity for Trichinella in the horse where the larvae were previously detected and the three other horses. However, when an excretory-secretory antigen was used, both tests showed negative results.
• Considering these results along with previous literature data, the researchers concluded that the horse likely acquired the Trichinella infection 8-10 months prior. They also confirmed the observations from experimental infections that both the muscle worm burden and specific circulating antibodies were lost several months after infection.