Increased Prevalence of Trichinella spp., Germany | CDC EID

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Volume 16, Number 6–June 2010
Research
Increased Prevalence of Trichinella spp., Northeastern Germany, 2008
Gunter Pannwitz,1 Anne Mayer-Scholl,1 Aleksandra Balicka-Ramisz, and Karsten Nöckler
Author affiliations: Veterinär-und Lebensmittelüberwachungsamt Ostvorpommern, Anklam, Germany (G. Pannwitz); Federal Institute for Risk Assessment, Berlin, Germany (A. Mayer-Scholl, K. Nöckler); and West Pomeranian University, Szczecin, Poland (A. Balicka-Ramisz)

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Abstract
In 2008, a Trichinella spp. outbreak occurred on a small family-owned pig farm in Mecklenburg–Western Pomerania in northeastern Germany. To obtain epidemiologic information on this outbreak, we determined that after 2005 the prevalence of Trichinella spp. in wild boars has increased in this region of Germany. We discuss the potential role of the raccoon dog in the increase in Trichinella spp. prevalence in the sylvatic cycle in this region. We believe that this increase could pose a threat to pigs kept in back yard conditions, and we provide recommendations to ensure public health safety.
Nematodes of the genus Trichinella infect a broad variety of mammals, birds, and reptiles and are distributed worldwide (1). Trichinellosis is a foodborne zoonotic disease caused by a parasite. Human infections occur after ingestion of raw or inadequately cooked meat containing parasite larvae (2). Pigs represent a major source of human infection, but meat from horses, wild boars, bears, and badgers have also played a major role during outbreaks (3,4).

Trichinella spp. can be transmitted by domestic and sylvatic cycles. The domestic cycle is maintained by feeding of swill to pigs and pigs feeding on animal carcasses or on synanthropic animals (e.g., rats, mice). In Germany, the domestic cycle disappeared >30 years ago (5). During 1998–2007, ≈436 million pigs were slaughtered and tested for Trichinella spp. by using artificial digestion according to regulation (European Commission [EC]) no. 2075/2005 (6). However, in 2003, 1 positive case was reported; it was in a pig kept in a back yard (7).

Currently, the major Trichinella spp. reservoir and source of infection for domestic pigs in Germany is wild boars (Sus scrofa), raccoon dogs (Nyctereutes procyonoides), and foxes (Vulpes vulpes). The most prevalent Trichinella spp. is T. spiralis, followed by T. britovi and T. pseudospiralis (8).

In the past 30 years, sporadic human infections with Trichinella spp. (0–50 reported cases per year) have occurred in Germany (7,9). These infections are usually linked to consumption of contaminated meat during holiday visits to high-risk countries (10). Autochthonous outbreaks occur infrequently, such as during 2005–2006, when 17 members of a large family in Mecklenburg–Western Pomerania were infected with Trichinella spp. after consumption of meat products from a pig reared and slaughtered at home (11).

We report a Trichinella spp. outbreak on a small family-owned pig farm in Mecklenburg–Western Pomerania in northeastern Germany during December 2008. We show that after 2005, the prevalence of Trichinella spp. in wild boars has increased in this region of Germany. Furthermore, we discuss the possibility that increased Trichinella spp. prevalence in wild boars is the result of high prevalence of the disease in neighboring Poland. The potential role of migration of raccoon dogs from Poland into Germany is also considered as a factor of increased prevalence.

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Increased Prevalence of Trichinella spp., Germany | CDC EID