Analysis: Danger signs we should all look out for

LEGIONELLA bacteria are water-loving bacteria that uncommonly cause infections in humans. Between 1995 and 2011, they were identified in between 15 and 44 Scottish cases each year.

Around two-thirds of cases are identified in people who have acquired their infection while abroad. People of any age can be affected, but the majority of cases are in those over the age of 50, and men are between two and three times more likely to have the infection than women. Cases peak each summer.

The infection cannot be passed from person to person, but is contracted after someone breathes in an aerosol/vapour containing the bacteria.

Sources include vapour/aerosols from industrial cooling towers, air-conditioning units, humidifiers, whirlpool spas, fountains and contaminated household showerhead units.

You are more likely to develop symptoms if you are in a group at increased risk (eg, if you have a chronic breathing or heart problem, or have a problem with your immune system), are over 50, are male, a smoker and if you drink to excess.

Initial symptoms include muscle aches and pain and headache, then high fever (greater than 40C), breathlessness and a dry cough. Three in every ten cases also have diarrhoea, vomiting, or are off their food. Around half become confused. If you are worried, contact your GP or NHS 24 straight away.

• Jim McMenamin is consultant epidemiologist at Health Protection Scotland.