Epizootiology of Trichinellosis in Pigs and Wild Boars in Western Romania,1998–2011

Introduction

T richinellosis is a major parasitic disease in Romania, where it represents a serious concern for both animals and humans (Neghina 2010, 2010a). Timis County, the largest Romanian county, is known as an important endemic region for trichinellosis. Previous studies in this area have revealed worrisome rates of human trichinellosis. Here we report for the first time data regarding trichinellosis in sacrificed animals (domestic pigs and wild boars) inspected from January 1998 to November 2011 in this region.

Methods

The data were collected from the Veterinary Public Health Department of Timis County, Western Romania. Results total of 5,586,431 domestic pigs on farms, 609,325 pigs in private households, and 823 wild boars were examined during the study period. Overall, 681 pigs (0.01%) on farms and 407 pigs (0.07%) in private households were found to be infected with Trichinella; therefore, the prevalence of trichinellosis in domestic pigs was 0.02%. Four wild boars were also infected (0.5%). The annual average numbers of infected pigs on farms and in private households were 48.6 and 29.1, respectively. The annual average number of infected wild boars was 0.3. During the study period, 54 foci were identified (average: 3.9 foci per year), and the number of human cases was 274 (average: 19.6 cases per year). Epidemiological and clinical data on human trichinellosis in this region were reported elsewhere (Neghina et al. 2009, 2010a, 2010b; Neghina 2010; Marincu et al. 2012).

Discussion

In Romania, the available data regarding the prevalence of trichinellosis in domestic pigs showed different values over time: 0.07% (1914–1952, Bucharest abattoirs), 0.055% (1932–1939, abattoirs in the entire country), 0.06% (1952–1957, Bucharest abattoirs), 0.034% (1950–1957, abattoirs in the entire country), 0.05% (1950–1957, all of Romania) (Cristea 1998), and 0.08–0.12% (1980–1993, all of Romania; Neghina et al. 2010a). For wild boars, the prevalence varied as follows: 0.23% (1956–1958), 0.25% (1980–1990), and 0.37% (1992–1994; Cristea 1998). Therefore, compared to the results of previous Romanian studies, the prevalence of infected animals is lower for domestic pigs (0.02%) and higher for wild boars (0.5%) in this study. The infective species was identified only once, in 2008, when larvae isolated by artificial digestion from a pig responsible for a human outbreak revealed Trichinella spiralis (Isolate Code ISS 1951; Neghina et al. 2010b).

In neighboring countries, the prevalence of trichinellosis in animals (swine and/or wild boars) is quite different, with higher rates in Serbia and an almost insignificant rate in Hungary. In all of Serbia the prevalence of trichinellosis in swine ranged between 0.06% and 0.17% (average 0.12%) during 1994–2003 (Cuperlovic et al. 2005). In the Branicevo District of the same country (bordering Western Romania and officially declared to be a Trichinella endemic region since 2003) the prevalence was 0.57% during 1995–2006 (Zivojinovic et al. 2009). In other the four districts surrounding Branicevo the prevalence ranged between 0.048% and 0.1% in 2008 (Zivojinovic et al. 2010). In 2000, the general prevalence in domestic pigs in Serbia was 0.56% (Zivojinovic et al. 2010). In another neighboring country, Hungary, the situation regarding trichinellosis in animals was considerably better. During the period from June 2006–February 2011, only 4 out of 16 million slaughtered pigs were found to be infected (a prevalence of 0.000025%). In wild boars, the prevalence was 0.0077% (Szell et al. 2012). In other European countries, the rates of infection were as follows: Montenegro 0.05% (2001) and 0.1% (2003) in swine, and 2.33% (2002) and 5.2% (2003) in wild boars (Cuperlovic et al. 2005); in Croatia the prevalence of trichinellosis in swine varied during 1998–2003 between 0.06% and 0.36% (Cuperlovic et al. 2005); in Germany, from 2002–2008, the prevalence in wild boars ranged between 0.0027% and 0.0032% (Pannwitz et al. 2010); in Slovakia it ranged between 0.06% and 0.11% from 2000–2007 (Hurnikova and Dubinsky 2009); and in Spain, the prevalence was approximately 0.77% among wild boars from the Toledo Mountains examined during the 2007–2008 hunting campaign (Garcia-Sanchez et al. 2009).

Nearly always related to trichinellosis in swine and wild boars, the status of human trichinellosis in Romania and in the countries bordering its western portion had the following rates (numbers of cases per 100,000 inhabitants): 0.97–7.4 (average 3.51) during 1998–2010 in all of Romania (Barzoi et al. 1999; National Center of Communicable Diseases Prevention and Control 2009, 2010; World Health Organization Regional Office for Europe 2011); 0–0.09 (average 0.03) during 1998–2009 in Hungary (World Health Organization Regional Office for Europe 2011); and 0.51–5.8 (average 2.74) during 1998–2010 in Serbia (Cuperlovic et al. 2005; World Health Organization Regional Office for Europe 2011).

Conclusion

Trichinella infection in animals continues to be a challenge for veterinary services in Western Romania due to its correlation with human foci. Although in the past several years (2009–2011), no animals were identified as positive during recent routine examinations of domestic pigs and wild boars, human outbreaks continue to occur annually in Timis County (2009: 1 focus; 2010: 1 focus; and 2011: 2 foci). The factors involved in these outbreaks may be related to the improper raising of “backyard” pigs in private households (especially in rural regions and by the gypsy minority), the lack of performing the mandatory post-slaughter inspection (in swine), and the increased frequency of recreational hunting campaigns and poaching (in wild boars).