Seven Lower Hutt councillors have been felled by a severe stomach bug after a function at the Dowse Art Museum cafe.
The councillors, including the mayor and deputy mayor, suffered symptoms including vomiting, diarrhoea, nausea and headaches.
Regional Public Health was focusing its investigations yesterday on a city planning function the council hosted last Monday night at the Dowse.
Four invited property developers also fell ill after the wine-and-nibbles function.
The 24 people who attended were served mini hamburgers and raw fish ceviche at the event, catered by Reka Cafe, which is based at the museum.
Mayor Ray Wallace had to cancel all meetings and appointments from Wednesday last week. "I'm still not firing on all four," he said yesterday.
He had lost 3.5 kilograms from the illness. "There's always a silver lining, although I can think of nicer ways of losing the weight."
Deputy mayor David Bassett, Barbara Branch, Lisa Bridson, Margaret Cousins, Tui Lewis and Margaret Willard also became ill.
So many councillors were sick that the council had to cancel a Wednesday night hearing of public submissions on its psychoactive substances policy.
Councillors Campbell Barry, Gwen McDonald, Chris Milne and Max Shierlaw were not at Monday's event. Angus Finlayson was, but did not eat the fish.
However, Michael Lulich said he ate the food and was in perfect health. "I had a bit of everything. It was delicious, and I felt good."
Annette Nesdale, of Regional Public Health, said lab results due back this week should shed light on what caused the outbreak.
Possibilities included food poisoning from ingredients or preparation methods, a sick cook, or a sick guest who spread the bug.
Depending on the severity and cause of an outbreak, a catering business could face a lowering of its food grade by the relevant city council, she said.
Reka manager James Hutton said the ingredients and food were beyond reproach.
He blamed the outbreak on a staff member who helped prepare the food, then fell ill the next day with a gastro bug.
There was no way of knowing the staff member had a bug on Monday, Hutton said.
"It didn't manifest until the following day."
The cafe did not allow staff to return to work for 48 hours after falling ill.
Councillors had eaten Reka's food hundreds of times without incident.
- The Dominion Post