Saturday, August 23, 2008

Exercise viewed from the relative safety of the couch

We are constantly urged to get out and do some exercise. This can be as simple as walking to work or doing a workout in the gym. However, walking at this time of the year in New Zealand has the distinct disadvantage that you can arrive at work looking like a drowned cat. The gym is less of a problem in that respect, but just pumping iron or running on a treadmill can get mighty boring.

What about mountain or cross-country biking? That can get your heart rate up and can be very exciting. There can also be a downside. Campylobacter.

There, I bet you immediately thought “What has mountain biking got to do with chilled chicken?” Certainly, we have heard a lot about Campylobacter and chicken meat over the last couple of years, much of it not good news. But this piece is not about transmission in poultry.

On July 5th and 6th this year, a mountain bike marathon was run on Builth Wells, Wales. The two-day event attracted 947 participants, up to 160 of whom became ill after the event. The conditions were very muddy and the course was contaminated with “sheep slurry”. The result was that contaminated mud splashed over the riders and their gear. An investigation* revealed that accidental ingestion of mud was the most statistically significant risk factor. Consumption of energy drinks and energy bars from feed stations was also associated with infection. It is easy to see how these factors might be linked – riders covered in mud would contaminate their drink bottles and dirty hands could transfer mud to food. Only the competitors became ill – support crew and visitors were not involved.

The running of this type of event over muddy agricultural land makes it almost inevitable that competitors would be exposed to zoonotic infectious agents, such as Campylobacter, Salmonella and Listeria.

It is very tempting to ask whether the high incidence of campylobacteriosis in new Zealand could be at least partly explained by our passion for strenuous outdoor sports that involve getting muddy and the high proportion of the country given over to farming. We already have some data on risk factors in New Zealand see
Perhaps it would be worth including questions in the surveys about contact with mud and activities such as cross country running or rugby.

* Griffiths, S. et al (2008) Preliminary report of the epidemiological investigation into the outbreak of diarrhoeal illness in Mountain Bike Marathon participants, Builth Wells. National Public Health Service for Wales

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