Five people are in hospital, but none have developed any serious complications, he said. There had been as many as 14 people in hospital at one point.
Allard said testing has shown that the two cases reported in Saint John are of a slightly different strain than the 22 cases in Miramichi and two in Bathurst, and therefore aren't connected with the others.
"Because of that, it makes us think that it's not likely something that has been distributed throughout the province, but it might be some local contamination that might be occurring in Miramichi itself," he said.
Allard said the two patients in Bathurst had visited Miramichi and eaten in restaurants there before they became ill.
He said there are no problems with the municipal water supplies in Miramichi, so officials are stepping up their investigation of restaurants and foods in the Miramichi area in their effort to track a source.
The Canadian Food Inspection Agency is assisting in the investigation.
The first patient reported having symptoms on April 23 and the most recent person believed to have contracted the bacterium became ill last Thursday.
New Brunswick gets an average of 12 cases of E. coli per year.
The Health Department is advising people to practice regular hand washing, washing of fruits and vegetables and properly cooking meat.