WHEREAS botulism in ruminants was an extremely rare disease in the British Isles until the beginning of the current millennium, hundreds of suspect outbreaks have been reported in the UK, Ireland and several European countries since then. In a paper summarised on p 640 of this issue, Payne and others (2011) report that 168 cattle and 19 sheep incidents were detected through scanning surveillance in England and Wales from 2003 to 2009. Their investigations have revealed that a key epidemiological factor in all sheep incidents, and in 95 per cent of cattle incidents, was proximity to broiler chicken litter. They report that the monthly incidence was highest when ruminants were grazing. Botulism is caused by toxins produced by Clostridium botulinum bacteria. These organisms are commonly found in the environment and will grow to high levels in decaying organic matter, including animal carcases. It is believed that contamination of broiler litter with the carcases of chickens that have died from various causes during production can render the litter dangerous for ruminants (reviewed by Haagsma 1991). However, the reasons for the recent increase in the incidence …