Enterohemorrhagic Escherichia coli outbreaks related to childcare facilities in Japan, 2010-2013.

Atsuhiro Kanayama,Yuzo Arima,Kazunori Oishi,Yuichiro Yahata,Kunio Kawabata,Takehito Saitoh,Tamano Matsui,Kazuhiko Kanou,Takuri Takahashi,Tomimasa Sunagawa

doi:10.1186/s12879-015-1259-3

Abstract

BackgroundEnterohemorrhagic Escherichia coli (EHEC) is an important cause of gastroenteritis in Japan. Although non-O157 EHEC infections have been increasingly reported worldwide, their impact on children has not been well described.MethodsWe collected national surveillance data of EHEC infections reported between 2010 and 2013 in Japan and characterized outbreaks that occurred in childcare facilities. Per Japanese outbreak investigation protocol, faecal samples from contacts of EHEC cases were collected regardless of symptomatic status. Cases and outbreaks were described by demographics, dates of diagnosis and onset, clinical manifestations, laboratory data, and relation to specific outbreaks in childcare facilities.ResultsDuring 2010–2013, a total of 68 EHEC outbreaks comprised of 1035 cases were related to childcare facilities. Among the 66 outbreaks caused by a single serogroup, 29 were serogroup O26 and 22 were O157; 35 outbreaks were caused by stx1-producing strains. Since 2010, the number of reported outbreaks steadily increased, with a rise in cases and outbreaks caused by stx1-producing O26. Of 7069 EHEC cases reported nationally in 2010–2011, the majority were caused by O157 (n = 4938), relative to O26 (n = 1353) and O111 (n = 195). However, relative to 69 cases of O157 (2 %) associated with childcare facility EHEC outbreaks, there were 131 (10 %) such cases of O26, and this trend intensified in 2012–2013 (O157, 3 %; O26, 24 %; O111, 48 %). Among family members of childcare facility cases, the proportion of cases that were symptomatic declined with age; 10/16 cases (63 %) aged 6 years or younger, 16/53 cases (30 %) 6–19 years old, 23/120 cases (19 %) 20–49 years old and 2/28 cases (7 %) 50 years or older were symptomatic. Thirty one of the 68 outbreaks (46 %) were classified as foodborne-related.ConclusionsChildcare facility EHEC outbreaks due to non-O157 serogroups, particularly O26 and O111, increased during 2010–2013. These facilities should pay extra attention to health conditions in children. As older family members of childcare facility cases appear to be less symptomatic, they should be vigilant about hand-washing to prevent further transmission.

Highlights

Enterohemorrhagic Escherichia coli (EHEC) is an important cause of gastroenteritis in Japan
EHEC cases in outbreaks have predominantly been attributed to EHEC O157:H7; recent studies have reported an increased in the number of cases affected by non-O157 serogroups, including O26, O103, O111, and O145 [3]
We identified 1035 outbreakrelated cases among the 68 childcare facility outbreaks that occurred during this period

Summary

Introduction

Enterohemorrhagic Escherichia coli (EHEC) is an important cause of gastroenteritis in Japan. Non-O157 EHEC infections have been increasingly reported worldwide, their impact on children has not been well described. Enterohemorrhagic Escherichia coli (EHEC) is known to cause diarrhea and hemorrhagic colitis in humans [1]. Vulnerable populations of EHEC infection include small children and the elderly. Severe cases are reported more often in children than in adults (under 65 years of age), and may include life-threatening hemolytic uremic syndrome (HUS) [2]. EHEC cases in outbreaks have predominantly been attributed to EHEC O157:H7; recent studies have reported an increased in the number of cases affected by non-O157 serogroups, including O26, O103, O111, and O145 [3]. Non-O157 E. coli tended to affect younger children more often than O157 in the USA [4]

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Discussion

Conclusion