Trichinella spiralis is a parasitic (nematode) worm which can infect a wide range of mammals (including humans) and some birds. The parasite is spread by the consumption of meat containing the immature (larval) stage of the worm. Natural infections are most likely in carnivores and omnivores such as foxes, bears, pigs, and rats but infection also occurs in horses.
Trichinosis is one of the most widespread foodborne parasitic diseases and occurs in most countries of the European Union but the UK is believed to be free from the infection. There have been no human cases acquired from meat produced in the UK for over 30 years; however, there have been occasional cases in the UK in people eating undercooked pig or horse meat sourced from abroad.
Animals infected with Trichinella generally show no obvious signs of disease unless the infestation is very severe. In humans the symptoms are variable, with milder cases of the disease often difficult to diagnose. In some cases there may be fever, muscle and joint pains, diarrhoea and swelling around the eyes and, in the most severe cases, potentially fatal neurological or cardiac complications.
Trichinella testing requirements
In line with the EU directive EU No 216/2014 and the move to a more risk-based approach at slaughter, from 1 November 2014 all pigs going to slaughter must be classified as being from ‘controlled’ or ‘non-controlled’ housing.