1. STATENS SERUM INSTITUT Outbreak of shigellosis in Denmark associated with imported baby corn – August 2007 Hannah Lewis EPIET Fellow, Statens Serum Institut, Copenhagen, Denmark Presented at EpiTrain V, October 26 2007

2. STATENS SERUM INSTITUT Background - Shigella spp. Faecal-oral route Low infective dose Incubation period: 1 - 3 days Illness: 4 - 7 days –Diarrhoea, often bloody (dysentery) –Fever and nausea Sh. sonnei cases in Denmark –Usually travel-related

3. STATENS SERUM INSTITUT Lab Notifications Sh. sonnei January 2000 – September 2007 Episodes by Month 2000 2001 2002 2003 2004 2005 2006 2007

4. STATENS SERUM INSTITUT Thursday 16 Aug - Detection Call from Medical Officer of Health/Regional Food Authority East –2 cases Shigella sonnei infection –Ate from salad bar in workplace –Both eaten raw exotic veg –2 different companies Cateringgruppen supplied canteens –206 companies, 4700 employees – Had received complaints

5. STATENS SERUM INSTITUT Thursday 16 August Case Finding –35 employees with GI symptoms –5 culture confirmed –Baby corn & sugar snaps Possibly not restricted to ´Cateringgruppen Large and widespread outbreak?

6. STATENS SERUM INSTITUT Friday 17 Aug - Control Measures Product recall - precautionary principle –Baby corn and sugar snaps –One wholesaler, Thailand –Distributed at beginning of August Press Release -Cook baby corn and sugar snaps Medical Officers of Health and clinical microbiologists informed Early Warning Response System alert

7. STATENS SERUM INSTITUT Descriptive Epidemiology - Demography 218 confirmed cases (1/08 – 30/09) –Excluded: 12 travel, 3 secondary, 2 alternative exposures 201 domestic primary cases Country-wide 75% female Median age 38 years (IQR:18, range: 2-92 years,)

8. STATENS SERUM INSTITUT Descriptive Epidemiology - Clinical Of 52 cases interviewed: 45% dysentery 13% hospitalised No deaths

9. STATENS SERUM INSTITUT Cases of Sh. sonnei infection in Denmark by day of onset, August 2007 (n=94) Recall of products Outbreak identified Last onset EWRS Cohort & micro results RASSF

10. STATENS SERUM INSTITUT Retrospective Cohort study Large company, 20+ symptomatic cases Electronic web-based questionnaire –Demographics & symptoms –Ate in canteen on 6-10 August? –Foods eaten on 6th & 7th August? Case definition: –Employee –Diarrhoea plus nausea or stomach cramps – Ate in the company canteen 6 - 10 August –Excluded travel-related cases

11. STATENS SERUM INSTITUT Wednesday 22 Aug - Cohort Results 103 questionnaires (response rate 61%) 23 cases Significant association between baby corn and illness Multi-variable analysis - no other products

12. STATENS SERUM INSTITUT Wed 22 August - Microbiology Results Baby corn analysis –High levels E. coli (>2000 cfu/g) –Serotypes of Salmonella enterica –No Shigella spp. New press release & RASFF - Product details

13. STATENS SERUM INSTITUT Molecular Microbiology 11 isolates same antibiotic resistance pattern –Resistant: tetracycline, ampicillin, sulfonamides, cephalothin, and streptomycin –Susceptible: nalidixic acid, ciprofloxacin, chloramphenicol, mecillinam and gentamicin Indistinguishable PFGE profile Sh. sonnei PFGE profiles –PulseNet US DB: 20,000 entries –Profile - 23 times Pulsenet US, Europe & Asia

14. STATENS SERUM INSTITUT Friday 31 August – Visit from Thai Trading Company & Authorities Packing house A Packing house B Trader X (Exporter) Wholesaler Y (Importer) Denmark Complicated production chain Good records Farms 100+

15. STATENS SERUM INSTITUT Friday 31 Aug: Connection Down-Under Danish Outbreak - Eurosurveillance –Same Antibiotic resistance pattern 12 cases, onset 9 - 27 August –Concurrent to Danish OB Acquired infection in Queensland

16. STATENS SERUM INSTITUT September: Link between outbreaks PFGE profile shared –PFGE profile indistinguishable Trace-back –Common Thai packing house –3 further countries WHO INFOSAN Alert –No associated cases

17. STATENS SERUM INSTITUT Source of Outbreak? Thai Authorities conducting investigation Environment and food handlers swabbed Probably post-harvest –Washing?

18. STATENS SERUM INSTITUT Conclusion Cohort study, food trace-back and microbiology = strong evidence for baby corn from Thailand Prevented additional cases of illness –Baby corn – long shelf-life (3 weeks) Previous large Sh. sonnei outbreak in Denmark –1998 –Raw baby corn imported from Thailand

19. STATENS SERUM INSTITUT Recommendations Cooking or blanching exotic vegetables Improved quality standards for imported fresh produce Sharing information internationally –At early stage –Using all available communication channels (International Health Regulations) Eurosurveillance EWRS RASFF Enternet Pulsenet WHO Infosan

20. STATENS SERUM INSTITUT Acknowledgments: Outbreak Team Department of Epidemiology, Statens Serum Institut, Denmark –S. Ethelberg, C. Kjelsø, L. Vestergaard, K. Qureshi, M. Howitz, K. Mølbak Department of Bacteriology, Mycology and Parasitology, Statens Serum Institut, Denmark –K.E.P Olsen, E.M Nielsen Regional Veterinary and Food Control Authority East, Denmark –M. Lisby, S.B. Madsen, P. Rasmussen OzFoodNet, Australia –M. Kirk, R. Stafford