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Increased incidence of trichinosis cases in Germany

06/1999, 19.04.1999

BgVV provides information on preventive measures

In the period from November 1998 to March 1999 more than 50 cases of trichinosis in humans were notified from 11 cities in North-Rhine/Westphalia (NRW). Trichinosis is a ubiquitous, mild to fatal zoonosis resulting from a foodborne infection with intestinal round-worms of the species Trichinella.

Together with the competent Land authorities and the Robert Koch Institute (RKI) the Federal Institute for Health Protection of Consumers and Veterinary Medicine (BgVV) is involved in its capacity as a National Veterinary Medical Reference Laboratory (NVRL) for Trichinosis in elucidation studies. The foods involved were identified as raw sausage (smoked sausage spread) and minced meat, which in some cases were produced from raw pork and also consumed raw. Within the framework of tracing studies the questionable food samples were recovered from sick people and amongst other things examined in the BgVV NVRL for trichina using a digestion method. This involves isolating trichina from a sample of minced meat which could be confirmed as Trichinella spiralis. Obviously the source of infection was raw pork which had not been or had not been properly examined for trichina or had not been subjected to an approved cold treatment method. Trichina infections in pigs occur as a rule as isolated cases which is why every pig must be examined. In later control examinations of product batches, which came from the plants concerned and contained pork, no trichina could be detected.

The carriers of trichina are all carnivorous animals like pigs and solipeds (horses, donkeys etc.). Humans become infected by consuming trichina-containing meat. According to the Federal Epidemics Act this is a notifiable disease. In Germany this disease occurs very rarely in humans as trichina testing is stipulated for all domestic and wild animal species (mainly pigs, horses and wild boar) for all Member States of the European Union, for inter-state trade and also for all meat imported from third countries in accordance with the Directive 77/96/EEC. In the case of pork trichina testing may also be replaced with cold treatment (deep-freezing). In recent years there have been more outbreaks of trichinosis in France and Italy caused by horsemeat which had been consumed raw or inadequately heated. Some cases involved more than 400 people.

Suitable prevention measures can render trichina in meat safe. Temperatures of at least 65oC reliably kill trichina whereby the colour at the heart of the piece of meat must have changed from red to grey. Another possibility is the deep-freezing of meat which kills the species Trichinella spiralis which occurs most frequently in domestic pigs. To this end, the meat with a diameter or a layer density of a maximum of 15 cm must be frozen over 20 days at -15°C or over 10 days at -23°C. When abroad, caution is in general advised in the case of products from home and individual animal slaughterings and also in conjunction with products from home and isolated slaughtering (in particular raw products like raw sausage or raw ham). The examination must be repeated when importing meat or meat products as gift parcels or as travel souvenirs. In this case contact should be made with the competent veterinary authority.

Work is currently underway in BgVV, in co-operation with RKI, on a pamphlet in the series "Pamphlets for Doctors", published by Deutscher Ärzte-Verlag, entitled "Trichinosis". It aims to provide, competent authorities and consumers with comprehensive information.

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