A study of Vero cytotoxin producing Escherichia coli (VTEC) O157 infections in Cornwall and West Devon was conducted to identify associations between human infection and contact with farm animals. In three years from November 1994 to October 1997, 63,000 stool specimens were submitted to four participating microbiology laboratories and screened for E. coli O157. Sixty-nine confirmed cases were interviewed to assess the extent of any direct or indirect contact with farm animals. Nine out of 22 investigations conducted on farms--in which animal rectal swabs, faecal specimens, fore-stream milk samples (first draw-off from teats), and various environmental samples were tested--yielded VTEC O157. In seven incidents one or more isolates from animals were indistinguishable from the isolate(s) from the human case(s) using phenotypic and genotypic subtyping. Cases associated with animal contact included farm visitors, holidaymakers, and members of farming families and farm workers.

Transmission of vero-cytotoxin-producing Escherichia coli O157 (O157 VTEC) is usually food-borne, particularly from undercooked beef or raw milk, or person-to-person. 1 Advisory Committee on the Microbiological Safety of FoodReport on Vero cytotoxin-producing Escherichia coli. ACMSF, London1995 Google Scholar Direct or indirect contact with various farmed or companion animals has also resulted in human infection. 2 Renwick SA Wilson JB Clarke RC et al. Evidence of direct transmission of Escherichia coli O157:H7 infection between calves and a human. J Infect Dis. 1993; 168: 792-793 Crossref PubMed Scopus (84) Google Scholar , 3 Parry SM Salmon RL Willshaw GA et al. Haemorrhagic colitis in child after visit to farm visitor centre. Lancet. 1995; 346: 572 PubMed Scopus (33) Google Scholar , 4 Shukla R Slack R George A Cheasty T Rowe B Scutter J Escherichia coli O157 infection associated with a farm visitor centre. Commun Dis Rep. 1995; 5: R86-R90 Google Scholar

From Logistic regression model, adjusted for age (by five years age band) and sex.The control groups are constituted of other cancers excluding cancers of the liver, kidney, thyroid, lymphomas and myelomas.The reference groups (or unexposed to dialysis) Include all cancer cases, or all other cancer cases diagnosed m the Varese cancer registry m the period 1983-87.Table : Risk of developing cancer in patients on dialysis considered.44 023 patient years were available for the study, 25 684 in men and 18 339 in women.479 cases of cancer at all sites was recorded.The average age at diagnosis was 59-5 years and the cases were on dialysis for an average of 6-37 years.There were statistically significantly raised risks of primary liver cancer, kidney cancer, thyroid cancer, lymphoma, and multiple myeloma.There were significantly decreased risks of cancers of the oral cavity and larynx, and a non-significant decrease in cancer of the oesophagus (table ).The excess of non- Hodgkin's lymphoma is similar to that found in recipients of renal transplants.The excess of liver cancer might be linked to materials used during dialysis.Longer and better survival of patients with end stage renal disease undergoing renal replacement therapy means that there are many elderly patients receiving therapy.Our results highlight the need for careful follow-up and for early detection of cancers in these patients.

Strains of enteropathogenic Escherichia coli (EPEC), enteroinvasive E. coli (EIEC) and Shigella were examined for Vero cytotoxin (VT) production and tested for the presence of VT genes in DNA hybridisation experiments with specific probes for VT1 and VT2. Twenty seven of 104 EPEC strains produced VT and in 26 of the 27 strains VT genes were detected. The VT+ EPEC strains belonged to serogroups O26, O55 and O128. Strains belonging to 8 other EPEC serogroups including strains isolated from 13 outbreaks, were all negative using both techniques, as were the 5 EIEC strains. It is concluded that VT1 and VT2 are not virulence factors in most EPEC infections. VT1 was demonstrated in all Sh. dysenteriae type 1 strains but neither VT1 nor VT2 were detected in strains of Sh. flexneri, Sh. boydii or Sh. sonnei.