This document analyzes EU surveillance data from 2009-2014 on shigellosis, a bacterial infection transmitted through contaminated food or water or directly from person to person through feces. The analysis found that domestically-acquired shigellosis cases increased over this period and accounted for over half of reported cases in 2014, with the proportion of cases among men doubling. Male-to-female ratios were highest among domestic cases, suggesting ongoing sexual transmission of certain Shigella strains like S. flexneri serotype 3a among men who have sex with men in Europe. The authors conclude countries should investigate domestic male cases and sexual transmission more and report such data to help monitor trends and facilitate public health interventions.

1. Is shigellosis among MSM a widespread
problem? An analysis of EU/EEA
surveillance data 2009-2014
Gianfranco Spiteri, T. Westrell, O. Mårdh
European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
Background
• Shigellosis outbreaks associated with sexual transmission among men who have sex with men (MSM) have been
reported in recent years from the United Kingdom, Germany and Spain, with severe infections among HIV-positive
MSM. A recent report from England identified high male-to-female ratios of reported domestic shigellosis cases as
an indicator of transmission among MSM.
• European Shigella surveillance data include limited information on sexual transmission. We therefore explored
surveillance data reported to ECDC to assess whether men are over-represented among domestic shigellosis cases,
suggesting possible sexual transmission among MSM and the need for specific public health prevention measures.
Results
• During 2009 to 2014, travel-related shigellosis cases decreased overall (from 1378 to 1013) and among both
genders as reported from 23 countries (Figure 1).
• In contrast, domestically acquired cases increased from 691 to 1071 and accounted for 51% of reported shigellosis
cases in 2014 compared to 33% in 2009; among men, domestically acquired cases doubled from 364 to 735 and
accounted for 63% of cases in 2014, compared to 39% in 2009.
• Male-to-female ratios increased among both travel-related (0.7 to 0.8) and domestic cases (1.1 to 2.3).
• Among domestic cases (2012-2014), the male-to-female ratio was 2.0 or above in the EU/EEA overall and in Austria,
France, Germany, Ireland, the Netherlands, Poland and Spain (Figure 2).
• Male-to-female ratios were 2.0 or above among domestic cases for: S. flexneri serotype 3a (2009-2014), 2a (2010-
2014), 1b (2010, 2012), 6 (2013) and other serotypes (2009-2014); S. sonnei (2011); and unknown Shigella species
(2014).
Conclusions
• The excess of males among domestically acquired cases of shigellosis in several countries suggests ongoing sexual
transmission particularly for S. flexneri serotype 3a among MSM in Europe.
• European countries with high male-to-female ratios among domestic shigellosis cases should consider more detailed
investigation of domestic male shigellosis cases including collecting data on sexual transmission.
• Reporting of sexual transmission of shigellosis cases at national and European level could facilitate interpretation of
trends and allow public health interventions, including raising awareness among clinicians and MSM, particularly
HIV-positive individuals at risk of severe outcomes.
Figure 1: Trends in shigellosis cases in the EU/EEA by place of
infection and gender, 2009-2014
Figure 2: Shigellosis male-to-female ratios in EU/EEA Member
States, 2012-2014
www.ecdc.europa.eu
Methods
• We analysed EU/EEA shigellosis surveillance data submitted to The European Surveillance System between 2009 and
2014.
• We assessed trends by gender and origin of infection among cases aged 16-65 years to determine the proportion of
males among domestically acquired and travel-associated infections.
• Male-to-female ratios were calculated for domestically acquired cases by country (aggregated for 2012-2014) and by
Shigella species (and serotype for S. flexneri) over time.