Trichinella threat remains despite EU measures, say researchers
Despite an EU directive (92/45), which requires wild boars hunted for commercial purpose to be examined for Trichinella larvae, an infection risk for humans remains, said the researchers.
The largest reported outbreak in Belgium to date is believed to have been caused by wild boar meat imported from Spain, where Trichinella spp. infection is in the wild boar population.
Trichinellosis burden
According to the European Centre for Disease Prevention and Control (ECDC), 320 confirmed human cases were reported in the EU during 2014.
In Mediterranean Europe, Italy and Spain reported 33 and 10 cases in 2012, said ECDC.
However, in the past five years, there has been a sharp decrease in human trichinellosis incidence rates in the EU due to better practices in rearing domestic animals and control measures in slaughterhouses.
Trichinellosis is a parasitic zoonosis caused by nematodes of the genus Trichinella.
Humans become infected after eating raw or undercooked meat from domestic pigs, horses or game containing Trichinella larvae.
The most important prevention measure is to freeze the meat or when preparing it ensure the core is cooked at a minimum of 67 °C to kill the larvae.
Belgian outbreak investigation
In the Belgian outbreak, during the last two weeks of November and first two of December 2014, 16 cases were identified and diagnosed with trichinellosis and six were female.
They all reported eating wild boar meat during the first week of November in three restaurants in the Belgian provinces of Limburg and Antwerp.
Three people who ate slowly roasted wild boar fillet or wild boar stew at the same time in the same restaurants as eight of the cases did not develop any symptoms.
Ten cases were hospitalised for a mean period of 14 days; three required admission to an intensive-care unit.
Diagnosis was confirmed by serology or the presence of larvae in the patients’ muscle biopsies by histology and/or PCR in which T. spiralis was identified.
The investigation traced the wild boar meat back to a single distributor and certified supplier in north-eastern Spain.
On inspection, there was evidence the cold chain had been respected in all three restaurants.
A total of 58 samples from 21 different batches were examined by magnetic stirrer artificial digestion at the Antwerp Institute of Tropical Medicine using 100g per sample in 1g portions but Trichinella larvae was not found.
No supplies of the suspected batch remained at the restaurants due to the timeframe of the recall.
Authorities in Spain reported no irregularities in the suspected slaughterhouse and no other outbreaks were reported in the EU during the same period.
The researchers said although it is a rare disease in Western Europe, it remains a threat despite measures taken at a European level.
“In countries where the prevalence of Trichinella in wildlife or domestic pork is still high, strict application of EU regulations and adequate control in slaughterhouses might be appropriate.
“In case of human infections, a transnational early warning system is important to alert the appropriate authorities, who can take swift action and control further spread of an outbreak.
“Our report also shows the importance of obtaining a detailed food consumption history as quickly as possible when a cluster of infections with a similar clinical pattern is observed.
“Finally, there is a need for more research and clinical trials to establish sound treatment guidelines for trichinellosis.”
Source: Eurosurveillance, Volume 21, Issue 37, 15 September 2016
“Outbreak of Trichinellosis related to eating imported wild boar meat, Belgium 2014”
Authors: P Messiaen , A Forier, S Vanderschueren, C Theunissen, J Nijs, M Van Esbroeck, E Bottieau, K De Schrijver, IC Gyssens, R Cartuyvels, P Dorny, J van der Hilst, D Blockmans
