The roots of hepatitis C infections in Scotland can be traced back to the Second World War, new research has found.

Scientists examined the spread of the hepatitis C virus (HCV) around the country by comparing the sequence of virus strains in infected individuals across various areas.

They revealed that HCV entered Scotland during the 1930s and 1940s while also spreading to other countries throughout the world, most likely through the mass treatment of soldiers in field hospitals.

Transmission of the virus north of the border started to increase in the 1970s, with different strains originating in Glasgow and Edinburgh. The Glasgow strains later spread to other regions, researchers found.

It was not until the 1990s that extensive HCV transmission was seen in Aberdeen and the predominant strain was one rarely identified outside the region.

Looking in more detail at the Glasgow strains, researchers were able to identify the key areas of the city involved in the spread of the virus up to the present day.

Focusing treatment and preventative measures in these regions could help to reduce the prevalence of HCV in Scotland, experts said.

The study was carried out by scientists from the MRC-University of Glasgow Centre for Virus Research and NHS labs.

They believe their findings will help shape work to prevent further infection and disease. About 36,700 people are currently thought to be infected with hepatitis C in Scotland.

The virus targets the liver and causes a chronic infection which may remain undetected for decades before symptoms appear.

It is a blood-borne virus which was once spread through the use of unscreened blood and blood products or through unsterilised medical equipment.

Its transmission is now mainly associated with the sharing of needles by drug users.

Lead study scientist Dr Carol McWilliam Leitch, of the Centre for Virus Research, said they plan to look at HCV spread in other Scottish regions and to extend the study across the UK.

She said: "HCV poses a significant public health challenge in Scotland as well as globally.

"There is currently no vaccine against the virus and the recently-developed antiviral drugs are not only extremely costly, but resistant strains have already emerged.

"Pinpointing regions of Scotland driving HCV spread will allow us to more effectively target treatments, monitor their effect and track resistant strains. These measures are essential if we are to combat the virus."

Professor David Goldberg, of Health Protection Scotland, said: "This unique study provides invaluable information on the origins of a country's hepatitis C epidemic.

"Such information is vital in understanding the spread of infection, so critical in shaping strategies to prevent further infection and disease."

The study, funded by the Medical Research Council, has been published in the Journal of Virology.