There may have been smaller campylobacter outbreaks in Hawke's Bay that were never picked up by health officials, researchers studying the 2016 Havelock North outbreak say.
That possibility is being investigated as part of a two-year study into the Havelock North water crisis, where 5000 people fell ill in August 2016.
Hawke's Bay has had one of the highest rates of campylobacter, per capita, in the country for several years and researchers were looking at historical trends between heavy rainfall and all types of reported gastroenteritis cases.
"The question is ... could it have happened without us even noticing?" Hawke's Bay District Health Board's population health acting director Dr Nicholas Jones said. Read more