Quick links

 

Further E. coli info

E. coli O157 outbreak investigations

VLA tests at Godstone Farm (Surrey), White Post Farm (Nottinghamshire), World of Country Life (Devon) and Big Sheep and Little Cow Farm (North Yorkshire)

Q&A

Q1: How has the VLA been involved in the investigation?

At the request of the Health Protection Agency, the VLA visited and took samples from:

  • Godstone Farm on 7th, 16th and 24th September,
  • White Post Farm on 18th September,
  • World of Country Life on 21 September and
  • Big Sheep and Little Cow Farm on 24 September.

The VLA has a long history of close working with the HPA and supporting it in protecting human health.  All appropriate resources are being focused on this and our experts are helping to identify exactly how these infections were caused.

Q2: What have you found at Godstone Farm?

We found that 33 of 102 samples taken on 7/9/09 yielded verocytotoxin producing E. coli (VTEC) O157. The positive samples came from ewes, lambs, pigs, goats, cattle and ponies, and from floor-samples of pooled rabbit droppings. We did not find it in a water sample (pond water) or the six samples of sandpit sand.

On 16th September, 17 environmental samples, 115 samples from ‘pet animals’ (rabbits, ducks, chickens, guinea pigs, ferrets, mice, chipmunks, turkeys, geese, quail and rhea) and droppings from wild rabbits were taken.  None of the animal specimens yielded VTEC O157.  Two of the 17 environmental samples, both from the floor of the main barn, yielded likely VTEC O157 (awaiting confirmation). Essentially this means that the germs recovered look very similar to VTEC O157 i.e. they are E.coli and the O157 serogroup but confirmation that they produce the verotoxins, and which ones, is required (see question 7 ).

Further sampling, including repeat sampling of pet rabbits, has all proved negative.

Q3: Are the E. coli found in the animals at Godstone Farm the same as the ones causing the infection in children?

11 of these 33 E. coli isolates collected on 7th September representative of different animal species have been examined in detail, and confirmed by the HPA to be indistinguishable from those causing infection in the human cases.

Q4: What samples have been taken from White Post Farm and what have you found?

Of 121 samples, collected from cattle, sheep, goats, alpaca, llamas, ponies, donkeys and pigs, five yielded VTEC O157 representing cows and calves (with no public access) and housed sheep and goats. The isolates are being further examined by HPA to see if they are the same as those causing human illness.

Q5: What samples have been taken from World of Country Life and what have you found?

Of 30 samples collected from sheep, goats, chickens, rabbits, pigs and an empty calf pen, VTEC 0157 was detected in eight samples representing a mixed group of sheep, goats and chickens which also contained a rabbit and a further positive result was found in a sample from a pig pen (with no public access). The isolates are being further examined by HPA to see if they are the same as those causing human illness.

Q6: What samples have been taken from Big Sheep and Little Cow Farm and what have you found?

Of 62 samples collected from sheep, goats, pigs, cattle, hens, a dog, ponies and small mammals, E. coli 0157 was detected in 32 samples from a variety of animal species (pigs, sheep, goats, cattle and hens). Representative isolates have been confirmed as VTEC O157 for each of the positive groups. The isolates are being further examined by HPA to see if they are the same as those causing human illness.

Q7: What is the difference between verotoxigenic E. coli and other E. coli?

Just as there are many different types of animal, e.g. breeds of dog, there are different types of E. coli.  One type of these bacteria produces a toxin (poison) called verocytotoxin (verotoxin), which is sometimes referred to as shiga toxin.  There are two types of this toxin; some strains produce one or other, and some produce both.

Q8: Are all verotoxin producing E. coli the same?

No.  They can be further broken down, with one called O157 being the most common to produce the disease in humans in Great Britain.

Q9: How do the toxins cause disease?

They damage cells in the body, and are particularly damaging to cells of the kidney.

Q10: How do you catch VTEC O157?

By ingestion through either eating contaminated food, including meat and non-meat products, or hand-to-mouth following contact with infected material/animals, especially their droppings.  Infection can also be spread person-to-person, particularly in closed settings.

Q11: Where do animals get it from?

They catch it from other animals or contaminated environment.

Q12: Does VTEC cause disease in animals?

Only some VTEC do.  The O157 serogroup does not.

Q13: What can farms do to reduce the risk?

Guidance and advice are available from the VLA and the HSE.  This primarily covers prevention of acquiring VTEC, prevention of spread if acquired and preventing establishment.

Q14: Does Defra/VLA ever screen animals for VTEC?

Yes, as part of surveys on cattle farms and at abattoirs.  This has shown that a few animals harbour VTEC, particularly cattle and sheep.  Infection is most common in calves.  We also test animals in support of the HPA and local authorities when there is a suspect link between human cases and animals (see ‘Further E. coli info’ on the right).

Q15: Why don’t you routinely check?

Because VTEC O157 doesn’t cause illness in animals, it is not looked for by vets in animal disease investigations.  Our surveys and other studies show that a small proportion of livestock and wild animals will be shedding these bacteria. This has led to the precautionary approach that management of public-animal exposures should assume a risk of exposure to VTEC from animals and appropriate hygiene precautions should be adopted routinely.

Q16: In other open farm investigations associated with human cases what proportion of animals were positive?

In 10 years of VLA experience of open farm investigations where human VTEC O157 illness has been possibly linked to animal contact, VTEC O157 has been confirmed in 19 (60%) of 31 farm investigations. On positive farms, the highest proportion of positive samples was in cattle (29%), followed by sheep (24%), donkeys (15%), pigs (14%), horses (12%) and goats (10%). It should however be remembered that these farms were sampled because of perceived links with human cases and not as part of a survey and results may not be representative of all open farms.

Quotes

Professor Peter Borriello, Chief Executive, VLA

"The VLA has a long history of close working with the HPA and supporting them in protecting human health. All appropriate resources are being focused on this and our experts are helping to identify exactly how these infections were caused."

Nigel Gibbens, Chief Veterinary Officer, Defra

"Joint HPA and VLA investigations have confirmed the presence of E. coli O157 bacteria in faeces from a wide range of animals on a premises in Surrey. The bacterium is known to have the capacity to infect a wide range of animals but the VLA advise that E. coli O157 has more commonly been found in ruminants, such as cattle, sheep and goats. The VLA is working closely with the HPA to assist with the ongoing investigations."

Reference

G.C. Pritchard et al (2009).  Verocytotoxigenic Escherichia coli O157 in animals on public amenity premises in England and Wales, 1997 to 2007. Veterinary Record  164: 544-9