u. k. - england and wales ( gb-ew ) · in england and wales (abbreviation: ew), three main national...

WHO Surveillance Programme for Control of Foodborne Infections and Intoxications in Europe

8th Report 1999-2000 Country Reports: United Kingdom: England and Wales

BfR

UNITED KINGDOM

England and Wales Population 1999: 52689891 Population 2000: 52943284

Area: 244 046 km2

1. General information

1.1 Sources of data

In England and Wales (abbreviation: EW), three main national surveillance systems for gastrointestinal infection are operated by the Public Health Laboratory Service Communicable Disease Surveillance Centre (PHLS CDSC). These include:

− The statutory notification of food poisoning

− The national surveillance scheme for laboratory-confirmed infections

− The national surveillance scheme for general outbreaks of infectious intestinal disease (IID)

Additionally, there is close liaison with the PHLS reference laboratories (Laboratory of Enteric Pathogens, Food Safety Microbiology Laboratory and the Enteric Virus Laboratory), all of which have national and international recognition for their reference facilities, and with external bodies such as the Veterinary Laboratories Agency, the Food Standards Agency, the Department of Environment, Food and Rural Affairs and the Department of Health.

WHO Surveillance Programme for Control of Foodborne Infections and Intoxications in Europe 8th Report 1999-2000

Country Reports: UNITED KINGDOM: England and Wales

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1.2 Statutory notification of food poisoning All doctors in clinical practice have a statutory duty to notify the appropriate officer of the local authority of all clinically diagnosed cases of diseases specified under the Public Health (Infectious Diseases) Regulations 1988. Food poisoning is one of the infections which is notifiable. In 1992, the Department of Health’s Advisory Committee on the Microbiological Safety of Food (ACMSF) defined food poisoning as “any disease of an infectious or toxic nature caused by or thought to be caused by the consumption of food or water.” This is a very sensitive definition of food poisoning which includes non-infective causes. Notification of food poisoning does not require that laboratory diagnosis be obtained. Therefore, it is usually impossible to determine the number of cases of notified food poisoning attributable to specific organisms.

1.3 National surveillance scheme for laboratory confirmed infections Clinical microbiology laboratories in England and Wales voluntarily report data on microbiologically confirmed cases of infectious disease to the Public Health Laboratory Service Communicable Disease Surveillance Centre (PHLS CDSC). The data reported include:

− organism − source laboratory (laboratory at which the specimen is initially examined) − reference laboratory − specimen date − case identifier − patient date of birth − patient gender

The following events must occur for cases to be included in the national surveillance database for laboratory-confirmed infections:

1. an infected individual must consult a clinician (general practitioner or hospital doctor) 2. the doctor must arrange for a specimen to be taken and referred to a clinical microbiology

laboratory 3. the laboratory must isolate or identify a pathogen 4. the laboratory must submit a report to the national surveillance centre

The national surveillance scheme for laboratory-confirmed infections does not necessarily provide a direct measure of the numbers of cases of infection in the population caused by those pathogens under surveillance. A number of factors influence the degree of the disparity between the number of recorded laboratory reports for any given pathogen and the true number of cases of infection in the population. These include:

• severity of disease

• duration of symptoms

• selectivity of screening protocols employed by diagnostic laboratories

• sensitivity of available diagnostic techniques



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The severity of the disease and the duration of symptoms associated with infection dictates both the proportion of cases that consult clinicians and the proportion of presenting cases from whom specimens are collected.

Laboratory screening protocols determine the investigations that are conducted on any given specimen, so ascertainment of cases by laboratory report surveillance for any given pathogen is influenced by the laboratory screening protocols in operation.

There are variations in the sensitivity of the routine diagnostic techniques employed for different species and subtypes of pathogen. The sensitivity determines the proportion of cases that are identified by laboratory investigation. The range of microbiological techniques used in the laboratories vary greatly in sensitivity and specificity. They include light microscopy; isolation, immunoassays, and novel techniques based on molecular biology.

Therefore, it can be seen that the disparity between laboratory report surveillance data and infection in the community is lessened for pathogens that cause severe disease and for which laboratories screen widely using sensitive methods.

Despite these caveats, voluntary reporting of laboratory-confirmed cases is the most reliable means of determining trends in the major foodborne pathogens.

1.4 National surveillance scheme for general outbreaks of infectious intestinal disease (IID) Since January 1992 enhanced surveillance of outbreaks of infectious intestinal disease has been conducted in England and Wales. General outbreaks are defined as outbreaks which affect people from more than one household. CDSC receives preliminary reports of general outbreaks of infectious intestinal disease (IID) from laboratories including the national reference laboratories, Consultants in Communicable Disease Control (CCDCs) in health authorities and local authority Environmental Health Officers (EHOs). Standardised questionnaires are then sent to the appropriate health authority in order to collect a minimum dataset on each outbreak. The investigating CCDC is asked to complete a questionnaire when the outbreak investigation is complete. The completed questionnaires are returned to the national surveillance centre and the data is entered into a database (Figure 1).

Figure EW 1

Outbreak surveillance

ENGLAND and WALES 1999-2000

L a b o r a t o r i e sC C D C E H O D H

G a s t r o in t e s t i n a l D is e a s e s D iv is io n C D S C

C C D CE H O H o s p i t a l

E p id e m io lo g y D iv is io n C D S C

P r e l im in a r y R e p o r t s

O u tb r e a k F o r m ( O F )

C o m p le te d O u tb r e a k F o r m

O F O F



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The following data are collected on the questionnaires:

• Health authority • Date of outbreak • Place of outbreak (hospital, restaurant, school, community etc.) • Pathogen • Mode of transmission (foodborne, person to person, mixed, other) And, additionally, in the case of foodborne outbreaks: • Type of food • Evidence (microbiological, epidemiological) • Numbers of cases, admitted to hospital, deaths • Faults associated with transmission of foodborne disease

Surveillance of general outbreaks of IID provides information on the specific risk factors associated with different pathogens and also trends in the importance of these factors. However, the completeness of the surveillance data is mainly dependent on the sensitivity of detecting outbreaks at local level. The ease of identification of outbreaks is influenced by many of the same factors that affect laboratory report surveillance (see above).

2. Statutory notification of food poisoning

The annual totals for food poisoning notifications in England and Wales in 1999 and 2000 were 86316 and 86258 respectively.

Figure EW 2

Food Poisoning Notification ENGLAND WALES 1977 - 2000

0

20000

40000

60000

80000

100000

Year

No. of registered cases

Food Poisoning



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3. National surveillance scheme for laboratory confirmed infections

Table EW1 shows the number of laboratory confirmed cases and incidence rates for illness due to a range of selected pathogens in 1999 and 2000. It should be noted that not all cases acquired disease through the consumption of contaminated food. These data also include imported cases of infection.

Figure EW 3 gives an overview of the number of laboratory reports of selected infectious intestinal pathogens between 1977 and 2000. As in previous years, the most commonly identified pathogen was Campylobacter. The number of Salmonella reports has continued to fall since the peak observed in 1997.

Table EW 1

Laboratory reporting of selected pathogens


Pathogen 1999 2000 No. Of cases

Incidence rate

No. of cases

Incidence rate

Non-typhoidal salmonellas 17532 33.27 14844 28.04 Staphylococcus aureus 84 0.16 - Clostridium botulinum 0 0 0 0 Campylobacter spp 54987 104.36 55887 105.56 Shigella spp 1262 2.40 966 1.82 Verocytotoxin producing E.coli O157

1084 2.06 896 1.69

Listeria monocytogenes 106 0.20 100 0.19 Vibrio cholerae O1/O139 33 0.06 16 0.03 Brucela spp 10 0.02 5 0.01 Hepatitis A 1389 2.64 1024 1.93 Other viral enteritis* 17701 33.59 19117 36.12 Echinococcocus spp 15 0.03 17 0.03 Trichinella spp 1 0.00 8 0.02 Giardia intestinalis 4240 8.05 4015 7.58 Entamoeba histolitica 304 0.58 257 0.49 Cryptosporidium parvum 4759 9.03 5799 10.95

*includes adenovirus (EM Faeces and Group F), astrovirus, norovirus, rotavirus, sappovirus



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Figure EW 3

Selected Gastro-intestinal Pathogens Reported by Laboratories ENGLAND WALES 1977 - 2000

010000200003000040000500006000070000

Year

No. of cases

Cryptosporidium Rotavirus Campylobacter Salmonella Shigella

In 1999, 17532 laboratory-confirmed cases of Salmonella infection were reported. This compares with a figure of 14844 for 2000. (Table EW 2). The percentage of cases due to S. Enteritidis fell from 61% to 57% during this period, while the percentage of cases due to S. Typhimurium rose from 14% to 18%.

Table EW 2

Salmonella serotypes identified


Serotype 1999 2000 No. of cases No. of cases

S. Enteritidis 10775 8468 S. Typhimurium 2424 2651 S. Virchow 535 300 S. Hadar 528 337 S. Newport 172 155 S. Infantis 143 163 S. Montevideo 125 133 S. Agona 112 145 S. Bredeney 89 92 S. Oranienburg 70 69



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S. Anatum 54 34 S. Saintpaul 51 31 S. Arizonae 51 46 S. Muenchen 44 37 S. Bareilly 43 43 S. Panama 42 43 S. Derby 30 43 S. Ohio 18 23 S. London 7 11 S. Tennessee 4 1 Others 2215 2019 Total 17532 14844

4. National surveillance scheme for general outbreaks of infectious intestinal disease

CDSC received completed reports for 516 and 654 general outbreaks of IID in England and Wales in 1999 and 2000. The mode of transmission was recorded for 86% and 87% of the outbreaks reported in those years. The most frequent mode of transmission was person-to-person spread, which accounted for 60% and 67% of the outbreaks in which mode of transmission data were available. Some degree of foodborne transmission was recorded in 23% and 19% of the reports received with mode of transmission data indicated in 1999 and 2000 respectively (Table EW 3). An overview of the outbreaks of IID reported during the period between 1993 and 2000 by mode of transmission is given in Figure EW 3.

Table EW 3

General outbreaks of infectious intestinal disease reported to PHLS CDSC by mode of transmission


Mode of Transmission 1999 2000 No. of

outbreaksNo. of

outbreaks Mainly foodborne 93 95 Foodborne plus person-to-person spread

23 23

Person-to-person spread 311 435 Waterborne 10 10 Other 7 8 Unknown 72 83 Total 516 654



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Figure EW 3

General Outbreaks of Infectious Intestinal Disease Reported to PHLS CDSC by Mode of Transmission ENGLAND WALES 1999 - 2000

0100200300400500600

1993 1994 1995 1996 1997 1998 1999 2000

Year

No. of outbreaks

Foodborne Foodborne & Person-to-personPerson-to-Person WaterborneOther Unknown

4.1 Aetiology The aetiology was confirmed by laboratory diagnosis in 88% and 70% of the outbreaks reported in 1999 and 2000. The most frequently identified pathogen in foodborne outbreaks was S. Enteritidis phage type PT 4, accounting for 20% and 18% of those outbreaks reported in 1999 and 2000 respectively.

Table EW 4

Aetiology of general outbreaks of infectious intestinal disease due to mainly foodborne transmission reported to PHLS CDSC

ENGLAND and WALES

Pathogen 1999 2000 No. of

outbreaksNo. of

outbreaksBacillus cereus 1 0 Campylobacter spp 7 8 Cl. perfringens 4 4 S. Enteritidis PT4 19 17 S. Enteritidis 11 7 S. Typhimurium 2 7 Other salmonellas 14 4 Sh. sonnei 0 1 Staph. aureus 4 0



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VTEC O157 7 6 Norovirus 5 10 Scombrotoxin 8 3 Unknown 11 28 Total 93 95

Salmonella strains other than S. Enteritidis PT4 accounted for 29% and 19% of the outbreaks in 1999 and 2000. Scombrotoxin was confirmed as the aetiological agent in 9% of the outbreaks reported in 1999, and Norovirus was identified in clinical specimens taken from individuals in 11% of the reported foodborne outbreaks in 2000 (Table EW 4). Figure EW 4 gives an overview of the aetiology of foodborne IID outbreaks reported between 1993 and 2000.

Figure EW 4

Aetology of General Outbreaks of Infectious Intestinal Disease Due to Mainly Foodborne Transmission Reported to PHLS CDSC

ENGLAND and WALES 1993 - 2000

0

20

40

60

80

1993 1994 1995 1996 1997 1998 1999 2000

Year

No. of outbreaks

020406080100120

No. of S. enteritidis PT 4 outbreaks

Other salmonella sp. Cl. perfringens NorovirusCampylobacter Scombrotoxin VTEC O157Bacillus sp. Staph. aureus S. enteritidis PT4

4.2 Vehicles of infection/Evidence Vehicles of infection were identified in 75% and 66% of the foodborne outbreaks of IID reported in 1999 and 2000 respectively. Microbiological evidence was obtained implicating specific foods in 22% of the outbreaks of 1999 and 2000. Descriptive evidence led to the identification of food vehicles in 46% of the outbreaks, while in 25% of the outbreaks, analytical epidemiological studies were used to identify food vehicles. The most frequently identified food vehicles in foodborne outbreaks of IID in 1999 and 2000 were poultry (25% and 21%) and fish/shellfish (15% and 17%) (table EW 5). An overview of the foods implicated in foodborne disease outbreaks reported between 1993 and 2000 is shown in figure EW 5. It should be noted that outbreak investigations sometimes identify a number of vehicles of infection.



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Table EW 5

Vehicles of infection in general outbreaks of foodborne IID reported to PHLS CDSC ENGLAND and WALES 1999-2000

Vehicle of infection 1999 2000 No. of

outbreaksNo. of

outbreaks Poultry 22 15 Red meat\Meat products 12 11 Fish\Shellfish 13 12 Milk\Milk products 6 2 Eggs 5 1 Desserts 6 5 Salads\Vegetables\Fruit 8 8 Sauces 3 2 Rice 3 2 Water 0 0 Miscellaneous 10 12 Total 88 70

Figure EW 5

Vehicles of Infection in General Outbreaks of Foodborne IID Reported to PHLS CDSC

ENGLAND WALES 1993 - 2000

01020304050

1993 1994 1995 1996 1997 1998 1999 2000Year

No. of outbreaks

Poultry Red meat/meat products Fish/shellfishDesserts Eggs MiscellaneousSalad/vegetables/fruit Rice Milk/milk productsSauces Water



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4.3 Settings Details on outbreak settings were recorded for all reported outbreaks. Restaurants/hotels were the most frequently reported outbreak settings, accounting for 42% and 56% of all outbreaks reported in 1999 and 2000.

Table EW 6

Settings implicated in general outbreaks of foodborne IID reported to PHLS CDSC ENGLAND and WALES 1999-2000

Setting 1999 2000 No. of

outbreaksNo. of

outbreaksRestaurant/hotel* 39 53 Retail store 14 10 Private home 8 2 Mass catering for spec. Groups~

18

12

School/kindergarten 5 2 Farms 2 1 Hospitals Mobile caterers Community

1 1 3

1 2 3

Other 2 9 Total 93 95

*Includes restaurants, hotels and bars

Mass catering for special groups includes residential institutions, halls, caterers, canteens, armed services, university, colleges, and holiday camps. Nine percent and 2% of the outbreaks registered in 1999 and 2000 respectively were linked to consumption of contaminated food in the private home (Table EW 6).

4.4 Contributing factors Factors contributing to foodborne disease outbreaks investigated in 1999 and 2000 are shown in Table EW 7. It should be noted that outbreak investigations sometimes identify a number of factors that combine to contribute to the transmission of infection. The most frequently noted factor contributing to transmission of diseases was cross-contamination of food during preparation.



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Table EW 7

Contributing factors identified in foodborne disease outbreak investigations reported to PHLS CDSC


Contributory factor No. of outbreaks

Infected food handler 27 Inadequate heat treatment 44 Cross contamination 73 Inappropriate storage 49 Other faults 30 Total 223

5. Additional Information

Notification data are collated nationally by CDSC on behalf of the Office for National Statistics (ONS). The collated data is published weekly in the Communicable Disease Report (CDR Weekly), which can be found at http://www.phls.co.uk/publications/cdr.htm.

For further reference on national and international data on foodborne diseases, please visit the web page http://www.euro.who.int/foodsafety/Surveillance/20020904_1

http://www.phls.co.uk/publications/cdr.htm

http://www.euro.who.int/foodsafety/Surveillance/20020904_1

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