FOUR have died after contracting Legionnaires' disease during a major outbreak in Milan, in north Italy. Local health chiefs are scrambling to find the source of the infection , which is believed to be coming from the water supply reaching people's houses. The lung infection can be caused by inhaling droplets of water from things like air conditioning or hot tubs.

Most people exposed to legionella bacteria do not develop symptoms. But as many as 15 per cent of those who do become ill suffer from severe disease, which can lead to life-threatening pneumonia. At least 53 cases of the disease have been recorded in the Lombardy region, according to figures from the local health authority, which says the numbers are correct as of August 19.

All infections have come from Corsico and Buccinasco, neighbouring areas in the southwest of Milan. The outbreak began in April when the first case started reporting symptoms. Since then, 12 people have been hospitalised and four have died.

The dead were "patients over 70 years of age, affected by comorbidities", the health officials said, which put them at higher risk of serious illness. Most read in Health Samples taken of the bug suggest all cases have come from one source, according to local media reports . Italian authorities are conducting widespread tests around the city to check all likely sources of this outbreak.

The most common form of transmission is inhalation of infected water sprays, jets or mists from contaminated water sources, .