E.coli (Hansard, 19 November 1998)

§ The Parliamentary Secretary, Ministry of Agriculture, Fisheries and Food (Lord Donoughue)

Most cases of VerocytotoxigenicEscherichia coli (VTEC) 0157:H7 infection are either sporadic or associated with family or household incidents. Details of the suspected sources of infection associated with such incidents are not routinely reported. As part of ongoing surveillance of outbreaks of infectious intestinal disease in England and Wales, 31 of the 55 general outbreaks of VTEC 0157:H7 reported to the Public Health Laboratory Service Communicable Disease Surveillance Centre between 1992 and 1997 were found to have a foodborne route of transmission. In Northern Ireland, no general outbreaks of VTEC 0157:H7 associated with beef, dairy, sheep or pig products have been reported.

In England and Wales a survey in 1995 of bovine faeces samples routinely submitted for diagnostic purposes to veterinary investigation centres found VTEC 0157:H7 in 0.86 per cent. of 6,495 samples. No association with season or herd type (beef or dairy) could be found. No surveys have been carried out on samples from sheep or pigs. Examination of faeces sampled from livestock submitted over a year between April 1995 and March 1996 to a single abattoir showed that almost 15.7 per cent. of cattle and 2.2 per cent. of sheep were excreting VTEC 0157. The same research project identified non-toxigenic E.coli 0157 in 0.14 per cent. of pigs, but this would be unlikely to be a source of infection for man.

In Scotland a study during 1991 to 1995 of cattle faeces samples submitted to Scottish agricultural colleges veterinary investigation centres demonstrated a prevalence of 0.27 per cent. (14 positive from 5,273 sampled).

In Northern Ireland, a survey carried out between November 1994 and December 1995 examined specimens of cattle faeces submitted for diagnostic investigation to DANI's Veterinary Sciences Division for E.coli 0157. The prevalence of 0157 was 2.2 per cent. (11 positives from 508 samples). While this survey was going on, a survey on carcasses in the nine principal abattoirs was carried out. E.coli 0157 was not detected in the 780 specimens examined. As part of an investigation into the microbiological quality of cattle carcasses in abattoirs, the level of 0157 contamination was ascertained on 210 faecal samples. Seven abattoirs were visited on three separate occasions between May 1997 and February 1998. Faeces samples from two animals were positive. DANI is currently investigating 179WA the possible links between 0157 related disease in farm families and the carriage of the organism in cattle on the farm.

Because VTEC 0157 is not considered to cause significant disease in animals, it is not routinely looked for in samples sent to VI Centres for diagnostic purposes. However, surveys at abattoirs throughout Great Britain are being planned to monitor the prevalence of VTEC 0157:H7 in rectal contents of cattle, sheep and, in association with the industry, pigs. A longitudinal study of faecal excretion of VTEC 0157:H7 in cattle to determine epidemiological patterns is also in preparation and will provide information on how the infection is spread. In addition, SOAEFD is currently funding a prevalence study in fattening cattle in Scotland.

VTEC 0157 is able to survive for long periods in the environment. It has been isolated from a number of livestock species, wild animals and birds. On farm, cattle are considered to be a main reservoir of infection but current knowledge of the epidemiology of the organism is limited and further research is being funded.

When animals on farm are suspected of being the source of infection in humans, veterinary officers will assist with the investigation and advise on best hygienic practice on farm for the prevention of the spread of the organism. Generally, the observation of good farm hygiene should help to reduce infection. In the current state of knowledge, however, attested practical measures to eliminate VTEC from farms are not available.