Pork worm, Trichinellosis, zoonoses

Pork worm (Trichinella spp) is a virtually microscopic parasitic worm that lives in the muscle cells of certain animals (pigs, horses, boars, foxes, etc.). Trichinellosis is a zoonosis (animal disease transmissible to humans) caused by the consumption of raw or under-cooked meat of animals contaminated by the Trichinella type parasite.
Present in every country worldwide, trichinellosis has a major impact on the hygiene and safety of food of animal origin. International regulations laying down the control of pork meat in the slaughterhouse have led to a reduction in this disease in the West.

Epidemiology in Europe

European countries have very contrasting prevalences depending on the species likely to be contaminated by pork worm (pigs, foxes, horses, boars, etc.).
There has not been a case of trichinellosis in humans linked to controlled meat in France since 1998. Over 1000 human cases were prevented through the identification of contaminated meat before consumption (2 horses, 9 pigs and several boars).
The cases arising in France result from consumption of non-controlled boar meat.

Trichinellosis may be prevented by cooking meat through at 63% or freezing meat at -20°C for 3 days.

Afssa's role

The National Reference Laboratory (NRL) for foodborne parasites (1)
The NRL, within the Laboratory for studies and research on animal disease and zoonoses carries out reference activities for trichinellosis and a certain number of foodborne parasites. It provides scientific and technical support to veterinary laboratories in French départements (72 laboratories to date) and runs a quality assurance plan for the diagnosis of animal trichinellosis. At present, France has the largest network of accredited laboratories screening this parasite.

The NRL has been coordinating European research activities on trichinellosis since 1999 (European contracts TRICHIPORSE, and now TRICHIMED in MedVetNet (2)). The strategy applied seeks to combat this major zoonosis by ensuring low diagnosis, setting up medical prophylaxis in endemic zones and organising veterinary control measures in France and Europe together with the European Union Reference Laboratory.

In 2005, more than 250,000 pig worm analyses were conducted annually on pigs. It is poised to quadruple to around a million a year in 2007 following the changes in European regulations.
The measures proposed to the DGAL in 1998 to resolve the problem of non-detection of pig worm larvae in routine laboratories were continued with the establishment of a quality assurance plan by the NRL. This includes the training of veterinary service technicians (since 1998), the use of a sound detection technique and the coordination of inter-laboratory aptitude tests (since 2004).

For domestic pigs, most checks come from free range pigs at higher risk. A massive increase in the number of checks occurred in 2005, following the setting up of self-checks in industrial pig farms exporting to Russia.

(1) Dr Pascal Boireau: Head of the National Reference Laboratory (NRL) for foodborne parasites
(2) MedVetNet is a European network of excellence working for the prevention and control of foodborne zoonoses

October 2007