Shigellosis - Annual Epidemiological Report 2016 [2014 data]

Key facts

• In 2014, 6 125 confirmed shigellosis cases were reported by 30 EU/EEA countries.
• The overall notification rate was 1.4 cases per 100 000 population in 2014.
• The notification rate was the highest in young children, followed by male cases aged 24–44 years.
• In some countries, the disease is mainly related to travel outside of the EU/EEA, while in others, domestically acquired cases dominate.
• There was a decreasing trend of shigellosis in the EU/EEA in the last five years.
• Several outbreaks due to sexual transmission among men who have sex with men were reported in recent years. 

Methods

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

The data used for this report were extracted from TESSy on 4 December 2015. Thirty countries reported data for 2014, three of which reported zero cases. Twenty-five countries reported data using the current EU case definition for shigellosis as published in 2008 and 2012, four used another definition, and two had not specified the used definition (Annex). The disease is under mandatory notification in 25 countries, notification is voluntary in four countries, and one country uses another type of surveillance system. All except two countries have comprehensive surveillance of shigellosis, the other two countries employ a sentinel system. Three countries have active surveillance systems while the rest have passive systems. Twenty-one countries have surveillance systems which integrate laboratory and epidemiological data.

Epidemiology

In 2014, 6 125 confirmed cases of shigellosis were reported in the EU/EEA (Table 1). The overall EU/EEA notification rate for confirmed shigellosis cases has slowly declined in the past five years and was at 1.4 cases per 100 000 population in 2014. Bulgaria, with 7.1 cases per 100 000 population, continued to report the highest notification rate of the EU/EEA countries, followed by Slovakia, Sweden, France and the UK (with 4.1, 3.5, 2.8 and 2.8 cases per 100 000 population, respectively) (Table 1, Figure 1).

Travel information was available for 2 946 (48%) of the confirmed cases, and of these, 42% were related to travel, mostly to India, Morocco and Egypt. More than 80% of the cases reported in Iceland, Finland, Norway and Sweden were travel-related. In contrast, almost all cases reported in Hungary, Greece, Slovakia and Belgium were domestically acquired. The proportion of travel-associated cases has decreased from 70% in 2010 to 42% in 2014 while the proportion of cases with known travel status has remained constant over the period. 

The highest case rate of shigellosis was observed among children 0-4 years old with 4.0 cases per 100 000 population (Figure 2). Notification rates in the 0-4 years of age group was highest in Bulgaria and Slovakia with 70.1 and 46.8 cases per 100 000, respectively. Male cases aged 25-44 years had the second highest overall notification rate with 2.5 cases per 100 000 population. The male-to-female ratio was overall 1.7:1 though among 25-44 year olds in the UK and Ireland, the male-to-female ratio was as high as 4.7:1 and 4.5:1, respectively.

Shigellosis in the EU/EEA follows a seasonal pattern, with peaks in late summer/early autumn. In 2014, the peak was particularly pronounced in September (Figure 3). A decreasing trend in the number of reported shigellosis cases has been observed since 2010 (Figure 4).

Threats description for 2014

No shigellosis-related threats were reported in 2014. 

Shigellosis, although relatively uncommon in the EU/EEA, remains of concern in some countries and for some population groups. Bulgaria and Slovakia continue to report high rates of infection, particularly among young children. The disease burden in these countries is mostly due to indigenous cases. In contrast, a number of countries, particularly the Nordic countries, mainly report cases associated with foreign travel, predominantly to countries outside of the EU/EEA. Shigellosis is endemic in most developing countries and is the most important cause of bloody diarrhoea worldwide [1].

In 2014, 21 foodborne outbreaks of Shigella (five of which were caused by S. sonnei) were reported by nine Member States [2]. The outbreaks affected 104 cases, of which 22 were hospitalised. Since shigellosis is not a zoonosis, the source in these outbreaks was most likely an infected food handler or food contaminated by human faeces during production. Several foodborne outbreaks of shigellosis in recent years have been attributed to fresh vegetables or herbs imported from outside of the EU/EEA [3-6].

Sexual transmission of shigellosis among men who have sex with men (MSM) has increased among domestically acquired cases in several European countries in recent years, particularly in England, Wales [7-9] and the Netherlands (personal communication, R Pinjacker, RIVM, the Netherlands, Sep 2016). This could possibly explain the large overrepresentation of male cases in the age group of 24–44 year-olds, particularly in the UK and Ireland. Oral-anal contact is often reported, and many cases are immunocompromised due to other infections, e.g. HIV [7-9]. A multidrug-resistant lineage of S. flexneri serotype 3a with high-level resistance to azithromycin has recently been described among the MSM population globally [10]. The azithromycin resistance is thought to have evolved due to treatment of other sexually transmitted diseases in MSM as azithromycin is the first-line treatment for e.g. gonorrhoea and chlamydia [10].

Public health conclusions

Shigellosis is not a zoonosis, and humans are the only known reservoir. Prevention of infection and control of outbreaks therefore relies on good personal and environmental hygiene practices to prevent faecal–oral transmission. Since the disease is endemic in large parts of the world, travellers benefit from adhering to common advice on how to avoid food- and waterborne infections when travelling.

Sexual transmission of shigellosis, particularly among men who have sex with men, is becoming more common in developed countries as transmission through poor hygiene and sanitation is decreasing. Targeted information campaigns to increase the awareness of shigellosis could help reduce the spread among these risk groups.

References

1. World Health Organization. Guidelines for the control of shigellosis, including epidemics due to Shigella dysenteriae type 1 [Internet]. Geneva: WHO; 2005. Available from: http://apps.who.int/iris/bitstream/10665/43252/1/924159330X.pdf.
2. EFSA (European Food Safety Authority) and ECDC (European Centre for Disease Prevention and Control), 2015. 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, 195 pp. doi:10.2903/j.efsa.2015.4329.
3. Guzman-Herrador B, Vold L, Comelli H, MacDonald E, Heier BT, Wester AL, et al. Outbreak of Shigella sonnei infection in Norway linked to consumption of fresh basil, October 2011. Euro Surveill 2011; 16(44). Available from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20007.
4. Löfdahl M, Ivarsson S, Andersson S, Langmark J, Plym-Forshell L. An outbreak of Shigella dysenteriae in Sweden, May-June 2009, with sugar snaps as the suspected source. Euro Surveill 2009 Jul 16; 14(28). Available from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19268.
5. Guzman-Herrador BR, Nilsen E, Cudjoe KS, Jensvoll L, Kvamme JM, Lindegard Aanstad A, et al. A Shigella sonnei outbreak traced to imported basil--the importance of good typing tools and produce traceability systems, Norway, 2011. Euro Surveill 2013; 18(49). Available from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20650.
6. Lewis HC, Kirk M, Ethelberg S, Stafford R, Olsen KEP, Nielsen EM, et al. Outbreaks of shigellosis in Denmark and Australia associated with imported baby corn, August 2007 – final summary. Euro Surveill 2007; 12. Available from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=3279.
7. Borg ML, Modi A, Tostmann A, Gobin M, Cartwright J, Quigley C, et al. Ongoing outbreak of Shigella flexneri serotype 3a in men who have sex with men in England and Wales, data from 2009–2011. Euro Surveill 2012; 17(13). Available from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20137.
8. Simms I, Field N, Jenkins C, Childs T, Gilbart VL, Dallman TJ, et al. Intensified shigellosis epidemic associated with sexual transmission in men who have sex with men –Shigella flexneri and S. sonnei in England, 2004 to end of February 2015. Euro Surveill 2015; 20(15). Available from: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=21097.
9. Gilbart VL, Simms I, Jenkins C, Furegato M, Gobin M, Oliver I, et al. Sex, drugs and smart phone applications: findings from semistructured interviews with men who have sex with men diagnosed with Shigella flexneri 3a in England and Wales. Sex Transm Infect 2015;0:1–5. doi:10.1136/sextrans-2015-052014. Available from: http://sti.bmj.com/content/early/2015/04/28/sextrans-2015-052014.abstract.  
10. Baker KS, Dallman TJ, Ashton PM, Day M, Hughes G, Crook PD, et al. Intercontinental dissemination of azithromycin-resistant shigellosis through sexual transmission: a cross-sectional study. Lancet Infect Dis, 2015. 15(8): p. 913-21.

* 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.