11043

	va1-sg19016.securesites.net

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SHIGELLOSIS, THAI BABY CORN - DENMARK

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On 16 Aug 2007, the Danish regional food authority (Fodevareregion 

Ost) and the Statens Serum Institut (SSI) became aware of an outbreak 

of _Shigella sonnei_ infections. The 1st cases to be reported were 

employees of 2 companies. They had eaten a variety of vegetables, 

including raw baby corn and sugar snaps in their workplace canteens. 

Preliminary interviews with further cases indicated that the probable 

source was imported baby corn or sugar snaps that had been 

distributed at the beginning of August 2007. The suspected foods were 

distributed by a wholesaler to green grocers, catering firms, 

restaurants, and shops throughout the country. Due to the strong 

suspicion about these food vehicles, the Veterinary and Food 

Administration issued a recall of baby corn and sugar snaps on 17 Aug 

2007. Furthermore, the SSI undertook investigations to determine the 

extent of the outbreak and its source.



A cohort study was undertaken in one of the many workplaces to have 

been affected by the outbreak to test the primary hypothesis that 

infection was associated with eating baby corn in the work canteen. 

Of 103 web-based questionnaire responses returned by 21 Aug 2007 from 

people who had eaten in the canteen, 24 reported gastrointestinal 

symptoms consistent with shigellosis. In the questionnaire, one set 

of questions focused on which days the employees had eaten in the 

canteen and the others on which food items had been eaten in the 

canteen on 6 and 7 Aug 2007, the 2 days when the suspected baby corn 

was known to have been served. There was a higher, although 

non-significant, relative risk of illness among people who had eaten 

in the canteen on 6, 7, or 8 Aug 2007. The relative risk for 

gastrointestinal symptoms among people who had eaten baby corn was 

employees who ate baby corn on 6 or 7 Aug 2007 was 64 percent.



Concurrent with the cohort study, notified cases from different parts 

of Denmark were interviewed and asked about food intake prior to 

onset of symptoms. The results of these interviews were consistent 

with baby corn being the source of infection. Moreover, a large 

number of workplaces were found to be affected by the outbreak and 

their canteens had served baby corn from the suspected imported 

batches in their salad bars. Taken together, the available 

epidemiological and food trace-back evidence strongly supported the 

finding that baby corn imported from Thailand was the source of the outbreak.



Between 6 and 24 Aug 2007, the SSI received notifications of 122 _S. 

sonnei_ isolates. This is almost triple the number of isolates 

confirmed for the whole of 2006 (46 isolates). A case in this 

outbreak was defined as any case of _S. sonnei_ infection acquired in 

Denmark after 1 Aug 2007 excluding those who had travelled to an 

endemic area in the 3 days before onset of symptoms or those that 

could be explained by an alternative exposure.



notified ones were excluded as travel-related). Cases were reported 

through the laboratory surveillance system from the whole of Denmark, 

but most cases (97/120, 81 percent) were reported from Zealand 

[Sjaelland, the largest island of Denmark (excluding Greenland, which 

is a Danish territory). - CopyEd.MJ]. The median age was 38 years 

(range 1-92 years) and 90 cases (75 percent) were female. Information 

2007, was available for 55 cases (Figure [for figure, see source URL 

- Mod.LL]). A quarter of these cases (13/55) were known to have been 

performed for 35 cases. Of these, all reported diarrhea, with half 

(17/35) experiencing bloody diarrhoea and 91 percent (32/35) 

reporting stomach cramps.



Antibiotic resistance typing on 11 samples taken from cases has 

revealed that isolates were resistant to tetracycline, ampicillin, 

sulfonamides, cephalothin, and streptomycin, but susceptible to 

nalidixic acid, ciprofloxacin, chloramphenicol, mecillinam 

[amdinocillin - Mod.LL], and gentamicin. Typing of isolates by pulse 

field gel electrophoresis is ongoing. Microbiological examination of 

the suspected batches of imported baby corn has detected high levels 

of _E. coli_, indicating fecal contamination. Additionally 

_Salmonella_ (serotypes as yet undetermined) have been found in 2 

batches. _Shigella_ have so far not been detected, but analyses are 

still ongoing.



An Early Warning Response System report was issued on 18 Aug 2007. 

The available information suggests that the outbreak is confined to 

Denmark but we encourage other countries to be aware of potential 

clusters of _S. sonnei_ cases. A small number of cases have been 

reported from Sweden but those contacted so far all appear to have 

been infected in Denmark. However, it is known that a small part of a 

batch of baby corn imported into Denmark was sold on to Sweden. This 

is currently undergoing microbiological examination to determine 

whether it was contaminated. Furthermore, among the cases in the 

outbreak there were individuals who acquired the infection on the 

ferry between Oslo and Copenhagen and it was found that baby corn 

from an incriminated batch was served on this ferry.



Due to the long shelf life of baby corn (3 weeks), the interventions 

made to trace the source of infection and to recall the product are 

likely to have prevented additional cases of illness. Although 

shigellosis does occur in Denmark and small outbreaks are 

occasionally seen, most cases are travel-related. The last large _S. 

sonnei_ outbreak in Denmark was in 1998, also associated with eating 

raw baby corn imported from Thailand (1).



infection related to uncooked 'baby maize' imported from Thailand. 

Eurosurveillance Weekly [1812-075X]. 13 Aug 1998; 8(33) 980813. Available from





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[This is another example of how the global market place contributes 

to foodborne illness thousands of miles away from harvest. It is not 

clear where in the process (from harvest to market place) the 

contamination occurred.



used to produce baby corn. Seed companies offer special types of seed 

to grow baby corn, but all of these grow plants and corn ears that 

are just as big as the usual corn. The secret is in the harvesting. 

Baby corn ears are picked by hand immediately when the silks emerge 

from the ear tips or a few days after. Corn matures quickly, so the 

harvest must be timed carefully to avoid ending up with normal corn 

ears. Baby corn ears are generally 4.5 cm to 10 cm (approx. 2-4 in) 

in length and 7 mm to 17 mm (0.3-0.7 in) in diameter.



Most baby corn commercially available is grown and processed in Asia, 

particularly in Thailand. Because baby corn must be picked by hand, 

it is too labor-intensive for most western farms. It has been an 

extremely important crop in Thailand since 1976, and other Asian 

nations have also begun producing and exporting it. Perhaps this is 

why baby corn is so often found in Asian recipes. - Mod.LL



A map of Denmark is available at



2005

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Shigellosis, unpasteurized milk curds, 2004 - Lithuania (Vilnius) 20051203.3494

1998

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Shigellosis, imported food - Denmark 19980813.1604]

...................................ll/mj/dk