There has been a rise in the number of people diagnosed with Legionnaires Disease in Glasgow.

The NHS Greater Glasgow and Clyde Public Health Protection Unit are investigating several recent cases as five people have tested positive for the disease. One elderly man with underlying medical conditions died last week, and a young woman – who also has pre-existing health problems – is currently in critical condition.

Public Health consultant, Dr Syed Ahmed, said an investigation would be carried out to establish whether there is a link between those who have tested positive.

"At this early stage in these investigations we have established no link between the cases," he said. "It is important to remember that Legionella cannot be spread from person to person. It is an uncommon bacterial infection."

Legionnaires' disease is a form of pneumonia caused by inhaling small droplets of water suspended in the air, which contain the legionella pneumophilia bacteria. They are usually spread through aerosols produced from water, such as air conditioning systems and showers.

Poorly-maintained water and plumbing systems are often blamed for increasing the risk of the bacteria developing. It can grow in water temperatures between 20 and 45ºc, although most healthy people who are exposed to the bacteria do not become ill. Instead, it mainly affects people who are susceptible because of age, illness, smoking and other pre-existing health conditions.