At a press conference today, Hastings Mayor Lawrence Yule said tests had confirmed that campylobacter was the cause of the outbreak and council staff were on the ground looking for the source and collating information.
Mr Yule was speaking soon after the Coroner's office announced it is investigating if a campylobacter infection contributed to the death of a Hawke's Bay woman.
Test results last night confirmed the 89-year-old woman, who died at Havelock North on August 13, had contracted campylobacter. A post-mortem examination revealed she also had other significant underlying health issues.
Mr Yule said that he was hoping to talk to the family of the woman "at some point".
At the press conference today, Hawke's Bay District Health Board chief executive Kevin Snee said it now appeared 4100 people were affected by the outbreak.
The numbers of patients presenting was steadily decreasing and the outbreak "very much on decline".
He said 15 patients were in a general ward and two in ICU. One patient in ICU had other conditions.
Auckland medical officer of health Dr David Sinclair said chlorination of the Havelock North water supply prevented further cases.
Reacting to call for an emergency to be declared, Dr Snee said "in sense we did" declare a medical emergency and he believed the DHB handled the outbreak "pretty well".
If people were not recovering or becoming sick again they should seek medical advice.
Boiled water measures should continue in Havelock North.
Mr Yule said there was no need for a Civil Defence emergency to be declared, saying emergencies were only declared when systems did not cope, but the system had "coped well".
The mayor also called on one of his councillors Wayne Bradshaw to produce information to support his allegation that the mayor and council knew about the bug in the water last Wednesday. Mr Yule insisted that the council only knew about it on Friday morning and he personally was told at 2.30pm on the same day.
He produced emails to support the timing.
Mr Yule said if Mr Bradshaw had nothing then he was "hindering" the relief operation and investigation and behaving "irresponsibly".
The mayor said the crisis was the single biggest issued he had dealt with and was "coping well physically" .
He pledged support for businesses in Havelock North that were affected by the gastro crisis. Ratepayers would help businesses but "how and when" was yet to be decided. The council was, in the meantime, offering $10,000 to the Havelock North Business Association for advertising.
A UV system water-cleansing plant would be operational in Havelock North by Friday next week.