Trichinella-infected pork products: a dangerous gift.

Abstract

During the past decade, Trichinella spiralis infection has become widespread among domestic pigs in most of Central and Eastern Europe (i.e. Bulgaria, Byelorussia, Croatia, Georgia, Latvia, Lithuania, Moldavia, Romania, Russia and Serbia), with prevalence reaching 0.16% nationally, and up to 50% in some villages [1xTrichinellosis: the zoonosis that won't go quietly. Murrell, K.D. and Pozio, E. Int. J. Parasitol. 2000; 30: 1339–1349Crossref | PubMed | Scopus (102)See all References, 2xNew patterns of Trichinella infections. Pozio, E. Vet. Parasitol. 2001; 98: 133–148Crossref | PubMed | Scopus (127)See all References]. Although, in recent years, tighter veterinary controls at slaughterhouses have decreased infection among domestic pigs, these controls are still lacking in villages, where many households keep several pigs. Furthermore, the high prevalence of Trichinella infection in domestic pigs has resulted in an increase of infection in wild boars and other sylvatic animals.The migration of people from Eastern Europe to the European Union (EU), mainly for work, has led to an increased quantity of pork products being sent from these countries to the EU as gifts, or brought back to the EU by migrants after visiting their country. This has caused several human outbreaks of trichinellosis. In Germany, in 2002, three people acquired trichinellosis after eating smoked wild-boar meat brought into Germany by travellers from Romania (www.promedmail.org 20021226.612). In Italy, in 2000, seven people acquired trichinellosis following the consumption of smoked pork sausages received from their relatives in Romania (www.promedmail.org 20010331.064). One of these people worked as a housemaid, and gave some of the sausages to her employer; the employer and his son both acquired trichinellosis. The sausages were found to be infected with 21 larvae per gram. In January 2003, the same housemaid gave smoked bacon from her relatives in Romania to the same employer, who sent us the bacon before consumption to check for Trichinella larvae: the bacon was infected with 12 larvae per gram. In November 2002 in Italy, two people acquired trichinellosis after eating pork sausages (six larvae per gram) received from Istria (Croatia). These sausages were part of a large batch believed to have infected approximately 200 people in Croatia (A. Marinculic, pers. commun.). The number of people affected was previously reported to be only 68 (www.promedmail.org 20021105). In all of these cases of trichinellosis in Italy, the larvae were identified as T. spiralis by multiplex PCR [3xPCR-derived methods for the identification of Trichinella parasites from animal and human samples. Pozio, E. and La Rosa, G. Methods Mol. Biol. 2003; 216: 299–309PubMedSee all References][3]. In London, in 1999, eight people from four different households acquired trichinellosis, after consuming pork salami received from relatives living in Serbia (www.promedmail.org 20000117.0064).Because human trichinellosis is relatively rare in many EU countries, local physicians often have problems with diagnosis because they are not familiar with the disease, which has no pathognomonic signs or symptoms. Delay in diagnosis and treatment allow the larvae to establish themselves in muscle, and to develop a collagen capsule, which renders them resistant to drugs [4xFailure of mebendazole in treating Trichinella spiralis infection in humans at the stage of encapsulating larvae. Pozio, E. et al. Clin. Infect. Dis. 2001; 32: 638–642Crossref | PubMed | Scopus (43)See all References, 5xOpinion on the diagnosis and treatment of human trichinellosis. Dupouy-Camet, J. et al. Expert Opin. Pharmacother. 2002; 3: 1117–1130Crossref | PubMed | Scopus (140)See all References]. In addition to constituting a risk to human health, imported pork products infected with T. spiralis threaten the pig industry in the EU, especially organic farms. For example, T. spiralis is not present in the domestic or wild animals of Italy or Switzerland [1xTrichinellosis: the zoonosis that won't go quietly. Murrell, K.D. and Pozio, E. Int. J. Parasitol. 2000; 30: 1339–1349Crossref | PubMed | Scopus (102)See all References, 6xThe domestic, synanthropic and sylvatic cycles of Trichinella and the flow among them. Pozio, E. Vet. Parasitol. 2000; 93: 241–262Crossref | PubMed | Scopus (106)See all References], and the accidental introduction of infected products would add a new pathogen to the food chains of these countries.Fortunately this problem is beginning to be addressed: on 1 January 2003, the EU began to apply measures to safeguard against the importation of animal products for personal consumption [7xSee all References][7]. However, several countries are exempt, many of which have a very high prevalence of Trichinella infection in both domestic and sylvatic animals, including Bulgaria, Estonia, Greenland, Latvia, Lithuania, Poland, Romania and the Slovak Republic.Because Trichinella infection in pigs is still endemic in small farms of Central and Eastern Europe, where veterinary controls are poor, it is important that political concerns do not obstruct the protection of consumers. Therefore, the importation of animal products from new-entry EU countries for personal consumption should also be controlled.