Yersiniosis - Annual Epidemiological Report 2016 [2014 data]

Key facts

• 6 839 confirmed yersiniosis cases were reported in 2014 in EU/EEA.
• The EU/EEA notification rate was 1.8 cases per 100 000 population.
• The highest rates were detected in 0–4-year-old children (10.0 cases per 100 000 population).
• The rate remained stable during 2010–2014 in EU/EEA.
• The highest rates were reported in Member States in north-eastern Europe.

Methods

Click here for a detailed description of the methods used to produce this annual report

In 2014, 27 EU/EEA Member States reported yersiniosis data, three of which with only partial population surveillance coverage. Ten of the 27 Member States used the 2012 EU case definition, nine countries used the one from 2008, six Member States reported data based on another case definition, and two countries did not specify their case definition. The majority of the Member States (24 of 27) undertook passive surveillance, and 17 countries reported cases through both laboratory and physicians and/or hospitals. Twenty-four of the 27 Member States reported case-based data.

Epidemiology

In 2014, 6 839 confirmed cases of yersiniosis were reported by 25 EU/EEA countries, with an overall rate of 1.8 cases per 100 000 population (Table 1). As in previous years, Germany accounted for the highest number of cases in the EU/EEA (N=2 470, 36.1%). Finland (10.6 cases per 100 000 population), Denmark (7.7) and Lithuania (6.7) had the highest rates. Figure 1 illustrates the country-specific rates per 100 000 population.

Threats description for 2014

No yersiniosis-related threats were reported in 2014. 

Discussion

In 2014, yersiniosis was the third most commonly reported zoonosis in the EU [1]. Yersinia enterocolitica was the most common species reported in the EU/EEA (97.7% of confirmed cases), followed by Y. pseudotuberculosis (1.8% of confirmed cases). Children 0–4 years of age were the most affected age group, with one quarter of the confirmed cases identified in this age group in 2014.  Previous studies from Germany and Sweden found that the main risk factor for Y. enterocolitica infection in young children was the consumption of raw pork products [2,3]. Differences in immunological response might explain why this age group is more susceptible to yersiniosis than older individuals [4]. In Norway, a case-control study covering all age groups showed that Y. enterocolitica case-patients ate significantly more pork products than matched population controls [5]. Drinking untreated drinking water was the second most important risk factor. Varying yersiniosis rates between countries are probably partly explained by different food consumption patterns, especially in young children, and by differences in national surveillance systems.

The proportion of hospitalised yersiniosis cases was relatively high, which is likely to reflect a surveillance bias because severe cases are more often diagnosed and reported. The fact that countries with the highest hospitalisation rates also reported low case rates supports this assessment [1].

Pigs are considered the main reservoir of Y. enterocolitica, whereas wild animals are probably the principal reservoir of Y. pseudotuberculosis in Europe [6]. Most of the Y. pseudotuberculosis cases are sporadic. In 2014, a yersiniosis outbreak with 36 cases occurred in Finland. It was concluded that the food vehicle contaminated with Y. pseudotuberculosis was raw milk [7]. In the same year, an outbreak of Y. enterocolitica infection was detected in Norway, with 133 reported cases [8]. The most likely source of the outbreak, which mainly affected military camps, was a salad mix containing imported radicchio rosso.

Public health conclusions

Pigs are the most important reservoir for Y. enterocolitica [3,5], and many cases are considered to be related to the consumption of undercooked contaminated pork or cross-contamination of other food items during handling and preparation of raw pork. Pork should be consumed only after adequate cooking, especially when it is given to young children. Proper kitchen hygiene is required to avoid cross-contamination.

References

1. European Food Safety Authority and European Centre for Disease Prevention and Control. The European Union summary report on trends and sources of zoonoses, zoonotic agents and food-borne outbreaks in 2014. EFSA Journal 2015;13(12):4329.
2. Rosner BM, Stark K, Höhle M, Werber D. Risk factors for sporadic Yersinia enterocolitica infections, Germany 2009–2010. Epidemiol Infect. 2012;140(10):1738-47.
3. Boqvist S, Pettersson H, Svensson A, Andersson Y. Sources of sporadic Yersinia enterocolitica infection in children in Sweden, 2004: a case-control study. Epidemiol Infect. 2009;137(6):897-905.
4. Cohen MB. Etiology and mechanisms of aute infectious diarrhea in infants in the United States. J Pediatr. 1991;118:S34-9.
5. Ostroff SM, Kapperud G, Hutwagner LC, Nesbakken T, Bean NH, Lassen J, et al. Sources of sporadic Yersinia enterocolitica infections in Norway: a prospective case-control study. Epidemiol Infect. 1994. 112:133-141.
6. EFSA Panel on Biological Hazards (BIOHAZ). Monitoring and identification of human enteropathogenic Yersinia spp – scientific opinion of the Panel on Biological Hazards. EFSA Journal. 2007. 595:1-30. Available from: http://www.efsa.europa.eu/en/efsajournal/pub/595.
7. Pärn T, Hallanvuo S, Salmenlinna S, Pihlajasaari A, Heikkinen S, Telkki-Nykänen H, Hakkinen M, Ollgren J, Huusko S, Rimhanen-Finne R. Outbreak of Yersinia pseudotuberculosis O:1 infection associated with raw milk consumption, Finland, spring 2014. Eurosurveill. 2015;20(40).
8. MacDonald E, Einöder-Moreno M, Borgen K, Thorstensen Brandal L, Diab L, Fossli Ø, et al. National outbreak of Yersinia enterocolitica infections in military and civilian populations associated with consumption of mixed salad, Norway, 2014. Euro Surveill. 2016;21(34):pii=30321.

Additional information

ECDC Surveillance Atlas of Infectious Diseases

European Food Safety Authority and European Centre for Disease Prevention and Control. The European Union summary report on trends and sources of zoonoses, zoonotic agents and food-borne outbreaks in 2014. EFSA Journal 2015; 13(12):4329. Available from: https://ecdc.europa.eu/en/publications-data/european-union-summary-report-trends-and-sources-zoonoses-zoonotic-agents-and-7   

European Centre for Disease Prevention and Control. Surveillance of seven priority food- and waterborne diseases in the EU/EEA. Stockholm: ECDC; 2015

_________

* The European Surveillance System (TESSy) is a system for the collection, analysis and dissemination of data on communicable diseases. EU Member States and EEA countries contribute to the system by uploading their infectious disease surveillance data at regular intervals.