Red squirrels can carry a variety of internal and external parasites, including lice, ticks and mites. It is essential to thoroughly clean squirrel feeders to avoid transmitting parasites and disease. Red squirrels are also susceptible to various diseases, some of them being:

Squirrel Pox
The most significant threat associated with grey squirrels is the spread and transmission of a disease called squirrelpox virus (SQPV). The grey squirrels carry the disease with no harmful effects to them. It can take only one grey squirrel to introduce this virus to a local population of red squirrels and then the virus can spread throughout the reds with devastating effect. For more information on the disease or about what to do if you find an infected red squirrel go to the RSNE information sheet.

An injectable vaccine has been developed which in laboratory testing is effective against squirrel pox.  Further work is required to develop a method of administering an oral vaccine to red squirrels in the wild.  This could potentially be an invaluable conservation tool.  For more information click here.

Squirrel Pox No 1

Red with Squirrel Pox

Squirrel pox No 2

Red with Squirrel Pox







Red squirrels are susceptible to other diseases and illness aside from SQPV.  Adenovirus is a relatively recently identified threat, and its impact on wild populations is still not fully understood. It is an enteric virus, therefore reds show no outward signs of the disease, however animals are often found dead. Current research by the AHVLA is continuing to shed light on the impacts of this disease as studies continue to identify confirmed cases. There is growing evidence that this disease may be introduced by rodents such as mice and rats, especially in the case of reds in captivity.  For more information click here.

Leprosy in red squirrels is a recent discovery, not because it is a new disease but because nobody had recognized it in the past. It is widespread, from Scotland to the Isle of Wight and Brownsea, and is likely to have been around in red squirrel populations for centuries. About 25 years ago, it was noted that some squirrels had ‘warty ears’ but they seemed well in other respects. It takes a long time for the disease to progress so most animals would die of other causes before the leprosy took hold. If you see red squirrels with what look like ‘warts’ on the ears or elsewhere on the body, please contact your local red squirrel conservation group. (Helen Butler, Wight Squirrel Project)

Red with leprosy

Red with Leprosy, Isle of Wight








Advice to Vets

Please see the RSNE Advice Note for Vets