Local authorities say they're confident campylobacter is what's given hundreds of residents a nasty gastro bug.

So far 62 people have been confirmed to have contracted the bug, and another 63 are considered to have probable cases.

Of that, 22 people remain in hospital and two in intensive care.

Those in Havelock North are being told to continue boiling water, and to stay away from workplaces for 24 to 48 hours.