Scotland's red squirrels are threatened by a new rare form of leprosy, according to scientists in Edinburgh.
Six cases are confirmed to have been caused by bacteria similar to the Mycobacterium lepromatosis since 2006, but experts say the disease is likely to have infected more of the rodents.
Professor Anna Meredith of the Royal Dick School of Veterinary Studies at Edinburgh University is leading the research.
She told BBC News: "We suspect this disease is more widespread than the six cases we have confirmed.
"Red squirrels are in decline. They are threatened by the grey squirrel and already face the major threat of the squirrelpox virus.
"This is the last thing that they need – another disease which could potentially threaten the population."
Symptoms of the squirrelpox virus include hair loss and severe swelling to the eyelids, snout, ears and feet. Infected animals were found across the country, including Moray Firth in the north and Dumfries and Galloway in the south.
This is the first time the disease has been found in the species and little is known about the transmission of the potentially fatal virus.
In the UK, Ireland and Italy, the number of red squirrels - Sciurus vulgaris - have decreased rapidly in recent years. The decline has largely been associated with the introduction of the eastern grey squirrel from North America and habitat loss.
Scientists have called for the public to report any sighting of squirrels which they believe may be infected. Researchers in Edinburgh said dead red squirrels could be sent to them by post provided they were appropriately packaged.
By gathering further data, researchers hope to build a more detailed understanding of the disease.
There is no suggestion of any risk to human health but they advise members of the public to follow basic hygiene rules before and after handling dead animals.