Holidaymakers who have visited Bali recently have been urged to see their doctor if they develop flu-like symptoms following an outbreak of Legionnaires’ disease on the Indonesian island.

Four Victorians have contracted the disease while holidaying in Bali in the past six months, including two men who visited in late December.

Victoria’s Chief Health Officer Dr John Carnie said a further six people had fallen ill with the disease in Western Australia after recent trips to Bali, prompting a warning to all those who fell ill after visiting the island.

“The Indonesian Government has been advised of the Australian cases and is investigating to determine the source of the infections,” Dr Carnie said.

Dr Carnie said the four Victorian men, aged from 45 to 82, had been treated for the illness after returning to Victoria and had recovered.

The first two Victorian cases were in August and October, while the latest two had visited Bali in late December.

Legionnaires’ disease causes flu-like symptoms such as headaches, fevers, chills and muscle aches, followed by respiratory problems and pneumonia developed over three or four days.

The symptoms can take up to 10 days to develop after the initial contact with the bacteria.

Groups at high risk of contracting the disease are people aged over 50, heavy smokers, heavy drinkers, diabetics, and people with chronic lung disease.

Dr Carnie said the legionella bacteria occurred naturally in the environment, predominantly in water and soil.

It is normally in very low concentrations but can increase, particularly in man-made aquatic environments with warm recirculating water, such as air conditioning cooling towers.