Geographical and temporal aspects of an outbreak of off-flavours in bulk-tank milk in Prince Edward Island, Canada.

The geographical and temporal dynamics of the outbreak of off-flavours in bulk-tank milk that occurred between September 2000 and June 2002 in Prince Edward Island (PEI) dairy herds were described using spatial, temporal and space-time scan statistics. Results suggested clustering both in time and space. We found one primary cluster (six case herds, feed off-flavour, October 2000 to January 2001) and two secondary clusters formed of feed (5 case herds, October 2000 to January 2001)) and rancid (five case herds, December 2000 to March 2001) off-flavours, respectively. The relative risk (RR) for producing off-flavoured milk was similar for these three clusters (RR=6.4).