Influence of age, sex and herd characteristics on the occurrence of Verocytotoxin-producing Escherichia coli O157 in Danish dairy farms.

Verocytotoxin-producing Escherichia coli (VTEC) O157 is an important emerging human pathogen. Cattle are considered to be the main reservoir for VTEC O157. The objectives of this study were to determine the prevalence of VTEC O157 in Danish dairy herds and to investigate the relationship between shedding of VTEC O157 and a number of animal and herd characteristics. Sixty dairy farms were visited once in August-October, and from each herd faecal samples from up to 50 animals were analysed for VTEC O157 by enrichment, immunomagnetic separation (IMS), and plating on selective agar. In total, 2419 animals were sampled, and 3.6% of these excreted VTEC O157. These animals were located on 10 farms (17%). On average, 21% of the sampled animals in the positive herds excreted VTEC O157. Register data, including age, sex, breed, housing conditions and herd composition, were extracted from a database. No influence of herd size or housing conditions was found. A strong effect of age was seen with 2-6-month-old calves as the high-risk age group (8.6% positive) in contrast to calves <2 months (0.7%) and cows (2.4%). There was a non-significant tendency of bull calves to have a higher prevalence than heifers within the age group of 2-6 months. Significantly, more of the herds characterised by having relatively many bull calves or many animals bought into the herd were positive for VTEC O157. Despite the low incidence of human VTEC O157 infections in Denmark, the prevalence in Danish dairy herds was found to be at a similar level as in many other countries.

[1]  T. Besser,et al.  A longitudinal study of Escherichia coli O157 in fourteen cattle herds , 1997, Epidemiology and Infection.

[2]  S A McEwen,et al.  Distribution and characteristics of verocytotoxigenic Escherichia coli isolated from Ontario dairy cattle , 1992, Epidemiology and Infection.

[3]  B. Synge,et al.  Verocytotoxin-producing E coli O157. , 2000, The Veterinary record.

[4]  P. Mead,et al.  Escherichia coli O157:H7 , 1998, The Lancet.

[5]  C. Siddons,et al.  A 1-year study of Escherichia coli O157 in cattle, sheep, pigs and poultry , 1997, Epidemiology and Infection.

[6]  W. Cray,et al.  Pathogenicity of Escherichia coli O157:H7 in the intestines of neonatal calves , 1997, Infection and immunity.

[7]  D D Hancock,et al.  The prevalence of Escherichia coli O157.H7 in dairy and beef cattle in Washington State , 1994, Epidemiology and Infection.

[8]  P. Chapman,et al.  Verotoxin-producing Escherichia coli infections in Sheffield: cattle as a possible source , 1989, Epidemiology and Infection.

[9]  E. Nielsen,et al.  Characterisation of Escherichia coli O157 isolates from Danish cattle and human patients by genotyping and presence and variants of virulence genes. , 2002, Veterinary microbiology.

[10]  J. Fleiss.  Statistical methods for rates and proportions , 1974 .

[11]  M. Blanco,et al.  Enterotoxigenic, verotoxigenic, and necrotoxigenic Escherichia coli isolated from cattle in Spain. , 1993, American journal of veterinary research.

[12]  A. Caprioli,et al.  Atypical strains of verocytotoxin-producing Escherichia coli O157 in beef cattle at slaughter in Veneto region, Italy. , 1997, Zentralblatt fur Veterinarmedizin. Reihe B. Journal of veterinary medicine. Series B.

[13]  R. Brosch,et al.  Prevalence and clonal nature of Escherichia coli O157:H7 on dairy farms in Wisconsin , 1996, Applied and environmental microbiology.

[14]  C. Siddons,et al.  A comparison of immunomagnetic separation and direct culture for the isolation of verocytotoxin-producing Escherichia coli O157 from bovine faeces. , 1994, Journal of medical microbiology.

[15]  R. Schall.  Estimation in generalized linear models with random effects , 1991 .

[16]  W. Melchers,et al.  Isolation and Characterization of Verocytotoxin-Producing Escherichia coli O157 Strains from Dutch Cattle and Sheep , 1998, Journal of Clinical Microbiology.

[17]  E. Skjerve,et al.  Occurrence of shigatoxinogenic Escherichia coli O157 in Norwegian cattle herds , 1998, Epidemiology and Infection.

[18]  C. Siddons,et al.  A fifteen month study of Escherichia coli O157:H7 in a dairy herd , 1997, Epidemiology and Infection.

[19]  P. Goldwater,et al.  New perspectives on the role of Escherichia coli O157:H7 and other enterohaemorrhagic E. coli serotypes in human disease. , 1998, Journal of medical microbiology.

[20]  W. Laegreid,et al.  Correlation of enterohemorrhagic Escherichia coli O157 prevalence in feces, hides, and carcasses of beef cattle during processing. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[21]  Occurrence of Escherichia coli O157 in Finnish cattle. , 2001, Veterinary microbiology.

[22]  J. Wells,et al.  Lessons from a large outbreak of Escherichia coli O157[ratio ]H7 infections: insights into the infectious dose and method of widespread contamination of hamburger patties , 1999, Epidemiology and Infection.

[23]  L. Garber,et al.  Prevalence of enterohemorrhagic Escherichia coli O157:H7 in a survey of dairy herds , 1995, Applied and environmental microbiology.

[24]  R. Wolfinger,et al.  Generalized linear mixed models a pseudo-likelihood approach , 1993 .