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Volume 5 No 19; 13 May 2011

Campylobacter now the leading cause of general foodborne outbreaks in England and Wales

Sixty one general outbreaks of foodborne infectious disease in England and Wales were reported in 2010 to the HPA’s electronic Foodborne and Non-foodborne Gastrointestinal Outbreak Surveillance System (known as eFOSS) – fewer than in the previous year (when there were 91 general outbreaks), according to the Agency’s latest data analysis.

The fall in the total number of general outbreaks § is mainly attributable to the decline in the number caused by Salmonella spp, of which there were only eight in 2010, the lowest number of salmonella outbreaks reported since the surveillance system was established in 1992.

In 2010, campylobacter displaced salmonella as the most frequently implicated causative agent in reported foodborne outbreaks (19/61 outbreaks, 31%), followed by norovirus (10/61, 16%) and those of unknown aetiology (suspected to be norovirus) (10/61, 16%) (see figure 1). Foodborne outbreaks caused by salmonella, the most frequently identified agent in outbreaks in recent years, accounted for 13% (8/61). Campylobacter was the causative agent in 80% of outbreaks associated with chicken liver pâté/parfait, the most frequently identified food vehicle in foodborne outbreaks in 2010.

One thousand, three hundred and ninety six people were affected by the 61 general foodborne outbreaks reported in 2010, of which 616 were laboratory confirmed cases; there were 82 hospitalisations and five deaths. Most outbreaks were reported from the South East of England (11) with fewest from West Midlands (1). Four national outbreaks were reported.

Figure 1. Causative agents in foodborne outbreaks in England and Wales, 2010Causative agents in foodborne outbreaks in England and Wales, 2010

* Other agents include Scombrotoxin, histamine, ‘suspected’ bacterial (Salmonella spp. and C. perfringens) and mixed agents.

 

Breakdown by setting, food vehicle and contributory factors

The majority of foodborne outbreaks in 2010 occurred in the food service sector (52/61, 85%), as was the case in 2009 and in earlier years [1, 2]. The next most frequent outbreak setting category was institutional/residential (6/61, 10%), followed by retail (3/61, 5%) settings (table 1). Of the food service sector outbreaks, over half occurred at restaurants and takeaways (30/52, 58%) and, of these, most served British (12/30, 40%) or seafood cuisine (6/30, 20%). All but one of the campylobacter outbreaks were linked to the food service sector, and most occurred at hotels (8/18, 44%) and restaurants (6/18, 33%). Two-thirds of the norovirus outbreaks and those suspected to be norovirus were linked to restaurants and takeaways (13/20, 65%).

Table 1. Settings for 2010 foodborne outbreaks reported to eFOSS, stratified by causative agent
 

Food Service [a]

Institutional/ Residential [b]

Retail [c]

Total

Campylobacter spp.

17

1

–

18

Norovirus

10

–

–

10

Suspect viral

10

–

–

10

Salmonella spp.

4

2

2

8

Others [d]

6

1

-

7

C. perfringens

3

–

–

3

VTEC O157

1

1

–

2

L. monocytogenes

–

1

1

2

Not known

1

–

–

1

Total

52

6

3

61

a. Includes restaurants, takeaways, hotel/ guest houses, pub/bars and event caterers.
b. Includes schools, hospitals and residential settings.
c. Includes supermarkets/ hypermarkets and smaller retailers.
d. Other agents include scombrotoxin, histamine, 'suspected' bacterial (Salmonella spp. and C. perfringens) and mixed agents.

A food vehicle was identified in 84% (51/61) of outbreaks. Poultry meat was the most frequently identified (20/63, 32%), followed by crustacea and shellfish (13/63, 21%) and red meat (10/63, 16%) (table 2). Poultry liver pâté/parfait dishes (poultry meat) (14/63, 22%) and oysters (crustacea and shellfish) (11/63, 17%) were the predominant specific food vehicles identified. Eighty percent (16/20) of poultry associated outbreaks were caused by campylobacter, while all crustacea and shellfish outbreaks were the result of confirmed or suspected norovirus. Red meat outbreaks were linked with a range of causative agents including campylobacter (2), norovirus (2), Clostridium perfringens (3), Listeria monocytogenes and those of unknown aetiology (2) (table 2). The evidence implicating a food vehicle in outbreaks included analytical epidemiology plus microbiological in 5% (3/61), microbiological evidence alone in 20% (12/61), analytical epidemiology alone in 16% (10/61) and descriptive epidemiology in 43% (26/61).

Table 2. Implicated food vehicles in 2010 foodborne outbreaks, stratified by causative agent
  Campy/er spp. Suspect viral Norovirus Salm.
spp. 		Others
[a] 		C. perfr/ns L. monocyt/nes Not known Total

Poultry meat

16

–

–

1

–

1

1

1

20

Crustacea & shellfish

–

–

4

–

–

–

–

–

13

Red meat

2

1

2

–

1

3

1

–

10

Composite/ mixed foods

2

–

–

1

3

–

1

–

7

Vegetables and fruit

–

–

1

3

–

–

–

–

4

Finfish

–

–

–

-

2

1

–

–

3

Rice

–

–

–

1

1

–

–

–

2

Desserts, cakes & confectionary

–

–

1

–

–

–

–

–

1

Potable water

1

–

–

–

–

–

–

–

1

Eggs/ egg dishes

–

–

–

1

–

–

–

–

1

RSE [b]

–

–

–

1

–

–

–

–

1

Total

21

10

8

8

7

5

3

1

63
[c]

a. Other agents include scombrotoxin, histamine, 'suspected' bacterial (Salmonella spp. and C. perfringens) and mixed agents.
b. Raw shell egg used as an ingredient in lightly cooked or uncooked food.
c. The total differs from the total number of foodborne outbreaks reported as more than one food vehicle may be identified in a single outbreak.

 

Outbreak contributory factors were identified in 87% (53/61) of the foodborne outbreaks. Inadequate heat treatment/cooking was the most commonly reported contributory factor (24/66, 36%), followed by cross contamination (12/66, 18%), an infected food handler (9/66, 14%), inappropriate storage (ie too long/too warm) (9/66, 14%), an unprocessed contaminated ingredient (4/66, 6%), poor personal hygiene (3/66, 5%), poor hand-washing facilities (3/66, 5%), and inadequate chilling (2/66, 3%). Campylobacter outbreaks were mainly associated with inadequate heat treatment (14/24, 58%) and cross contamination (5/24, 21%). The main contributory factor for norovirus outbreaks was infected food handlers (6/9, 67%).

The rise and fall of campylobacter and salmonella, respectively

The reduction in outbreaks attributed to Salmonella spp. - only eight outbreaks in 2010 compared with 28 in 2009 and continuing a decade-long trend, particularly in those caused by S. Enteritidis (figure 2) - mirrors further reported decreases in salmonella laboratory-confirmed cases in 2010 [3], and clearly indicates the effect of successful intervention measures undertaken in poultry flocks [4].

Bucking this trend in salmonella outbreaks, a further increase in campylobacter outbreaks was reported in 2010 compared to 2009 (18 vs 13), with an increment in those linked to consumption of poultry liver pâté/parfait (9/13 in 2009 vs 14/18 in 2010) [5, 6]. Similarly, cases of infection with campylobacter in England and Wales also continued to increase in 2010 compared to 2009 [7]. Evidence gained from outbreaks during 2010 revealed that, as in 2009, livers used to make the parfait or pâté by caterers were deliberately undercooked allowing the liver dish to remain pink in the centre [5, 6], despite specific food safety advice tailored for caterers [8].

Figure 2. The decline of salmonella outbreaks reported to eFOSS,
England and Wales, 1992-2010
The decline of salmonella outbreaks reported to eFOSS,

 

The eFOSS surveillance system

The investigation and reporting of foodborne outbreaks is mandatory within the European Union (EU) (Directive 2003/99/EC). The HPA's electronic Foodborne and Non-foodborne Gastrointestinal Outbreak Surveillance System (eFOSS) generates a national minimum dataset to facilitate the targeting of actions to improve food safety in the UK and EU [9]. The dataset includes information on the severity of disease, the importance of different food types as outbreak vehicles, the agents associated with these food types, along with the factors contributing to the occurrence of foodborne outbreaks.

The eFOSS data for 2010 presented in this article has again shown that the majority of outbreaks were linked specifically to food service premises, and that these were related to inadequate cooking of the food and/or cross contamination in the kitchen. Caterers need to adopt appropriate control measures and follow food safety advice provided by the Food Standards Agency [10]. Proper cooking, improving hygiene and lowering the risk of introducing campylobacter, norovirus and other pathogens into the food service sector are needed in order to reduce the risk of infection.

§ A general outbreak is an incident in which two or more people, from more than one household, or residents of an institution, thought to have a common exposure, experience a similar illness or proven infection (at least one of them having been ill).

References

1. Gormley FJ, et al. A 17-year review of foodborne outbreaks: describing the continuing decline in England and Wales (1992-2008). Epidemiology and Infection 2011; 139: 688-99.

2. Health Protection Agency. Increase in reported foodborne outbreaks in 2009. Health Protection Report 4(19) (14 May 2010). Available at: http://www.hpa.org.uk/hpr/archives/2010/hpr1910.pdf, 2010 (accessed 15 April 2010).

3. Health Protection Agency. Salmonella by Serotype. Available at: www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Salmonella/
EpidemiologicalData/salmDataHuman/ (accessed 10 May 2011).

4. European Food Safety Authority. The Community Summary Report on trends and sources of zoonoses, zoonotic agents and food-borne outbreaks in the European Union in 2008. The EFSA Journal 2010; 8: 1496 (410pp).

5. Health Protection Agency (2010). Foodborne outbreaks of campylobacter associated with consumption of poultry liver pâté/parfait - spotlight on caterers and food safety. Health Protection Report 4 (83) (3 December 2010). Available at: http://www.hpa.org.uk/hpr/archives/2010/news4810.htm#campy (accessed 15 April 2011).

6. Little CL, et al. A recipe for disaster: outbreaks of campylobacteriosis associated with poultry liver pâté in England and Wales. Epidemiology and Infection 2010; 138: 1691-4.

7. Health Protection Agency. Campylobacter infections per year in England and Wales, 1989-2010. Available at: www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/Campylobacter/EpidemiologicalData/
campyDataEw/ (accessed 10 May 2011).

8. Food Standards Agency (FSA) (2010). Caterers warned on chicken livers. Available at: http://www.food.gov.uk/news/newsarchive/2010/jul/livers (accessed 15 April 2011).

9. Health Protection Agency. Foodborne Outbreak Surveillance and Risk Assessment. Available at: www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/
FoodborneOutbreakSurveillanceAndRiskAssessment/ (accessed 12 May 2011).

10. Food Standards Agency (FSA) (2006). Safer food, better business. Available at: www.food.gov.uk/foodindustry/regulation/hygleg/hyglegresources/sfbb/sfbbcaterers/ (accessed 15 April 2011).