Campylobacteriosis outbreak associated with ingestion of mud during a mountain bike race

Epidemiol Infect. 2010 Dec;138(12):1695-703. doi: 10.1017/S095026881000049X. Epub 2010 Mar 25.


One of the largest reported campylobacteriosis outbreaks in Canada occurred in June 2007 in British Columbia, associated with a mountain bike race that took place in muddy conditions. A retrospective cohort study was conducted and environmental samples were collected and tested. There were 537 racers included in the study and 225 racers (42%) reported diarrhoeal illness after the race. C. jejuni clinical isolates (n=14) were found to be identical by multi-locus sequence typing. Although univariate analysis suggested water consumption and mud exposure as significant risk factors, multivariate analysis revealed that on direct ingestion mud was significantly associated with illness (OR 4·08, 95% CI 2·03-8·21). Contaminated mud was thus the most likely source of Campylobacter infection. We identified other unpublished reports of outbreaks associated with bike races in rainy or muddy conditions; these underscore the importance of educating racers and raising public awareness of the risks of mud ingestion.

MeSH terms

  • Bacterial Typing Techniques
  • British Columbia / epidemiology
  • Campylobacter Infections / epidemiology*
  • Campylobacter Infections / microbiology
  • Campylobacter jejuni / classification
  • Campylobacter jejuni / genetics
  • Campylobacter jejuni / isolation & purification*
  • Cluster Analysis
  • Cohort Studies
  • DNA Fingerprinting
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Diarrhea / epidemiology
  • Diarrhea / microbiology
  • Disease Outbreaks*
  • Eating*
  • Humans
  • Retrospective Studies
  • Sequence Analysis, DNA
  • Soil*
  • Sports


  • DNA, Bacterial
  • Soil