THE family of a Legionnaires’ victim is “disturbed” by their relative’s sudden death, which they believe should have been prevented.

The 73-year-old retired electrical engineer died of the disease on Thursday.

His death comes as the health department confirms a fourth person has fallen ill with the disease, linked to an outbreak in Gladstone Park.

Two men and a woman aged in their 60s to 70s have been hospitalised, including one in intensive care.

The dead man’s family called for stricter regulations of cooling towers following their loved one’s death.

However the state’s deputy health officer Brett Sutton said there was no way to completely eliminate legionella risk and that the system is “as strong as anywhere in the world.”

“We have to accept there is no such thing as zero risk with legionella,” he said.

Relative James Downing said he was dismayed to hear the system cannot fully protect the community.

“Clearly from what’s been said there is nothing more that can be done and that we must put up with it,” he told the Herald Sun.

“It’s very disturbing. I thought this thing had been nailed. I thought there was a regime in place to kill it and clearly there is but it doesn’t work all the time.”

Nine cooling towers have been tested and disinfected following the illness cluster. The testing found legionella bacteria in a cooling tower in a Gladstone Park residential area — close to each of the patients’ homes.

Dr Sutton said: “It would be reasonable to assume that’s where it came from. We are confident we have covered the likely source.”

Victoria has about 2900 cooling towers which are mapped and disinfected twice a year. Those in high-risk areas including hospitals and nursing homes are cleaned more regularly.

Symptoms of Legionnaires’ disease typically evolve over three or four days and can include headaches, fever, chills, muscle aches and pains followed by respiratory problems and pneumonia.

The health department has warned new cases could develop up until mid-May, as the illness can occur up to 10 days after initial contact with the bacteria.

Anyone concerned about their health should contact their GP.