In the UK, there are many diseases that are transmissible between humans and animals. These are known as zoonotic diseases. Some well-known examples include rabies, ringworm and salmonella. Thankfully, there have been no recorded incidences of squirrel pox in humans.
Squirrel pox is a disease that affects wild squirrel populations in the UK. It is carried by both grey and red squirrel species but symptoms of the disease are only apparent in the red squirrel. Squirrel pox has been largely responsible for the decline of red squirrel populations in the UK, hence why they are a protected species.
Looking after your local environment and wildlife is important and there are several things you can do to help your local red squirrel population.
In the UK, there are two squirrel species that you can find in woodlands, parks and even your own garden: the red squirrel and the grey squirrel.
Red squirrels are a species native to the UK. The original population of around 3.5 million red squirrels has now been decimated to around 120,000 - 160,000 squirrels living in habitats throughout the country. This decline has been attributed in part to the introduction of the North American grey squirrel to the UK, which first occurred in the 1800s.
All wild animals compete in a race for survival, especially when resources are shared and become sparser. Many of the red squirrels' habitats and resources have been colonised by the grey squirrel, creating competition between the two.
Unfortunately, with their growing numbers, larger size and resilience, the grey squirrel has shown that it has the advantage over the red squirrel.1 They also carry and spread the squirrel pox virus, a disease that they are relatively resistant to but is deadly for the red squirrels.2
Causes of squirrel pox
Squirrel pox is a virus carried by non-native grey squirrels. The first cases of the virus started to appear in the 1980s, in areas where the red and grey squirrel were living together.3
Carriers of the squirrel pox virus will shed the virus into the environment (with the virus surviving up to 4 weeks outside of a host in dry weather). Therefore, red squirrels are highly prone to getting infected, if they are in an outbreak area, through contact with contaminated “body fluids and shared parasites”.4
Signs and symptoms of squirrel pox
Symptoms of squirrel pox that manifest in an infected squirrel include:
- Ear, nose, mouth and genital lesions
- Oozing scabs and ulcers
- Drowsiness and lack of activity
- Clumsy movements
- Excessive intake of water
The disease is fatal for the red squirrel. The infection process is painful and leads to squirrels suffering from starvation and becoming vulnerable to other dangers.
Management and treatment for squirrel pox
Red squirrels can be found across the UK. Though most (estimated at around 75% of the total population) are concentrated in various protected woodlands and National Parks throughout Scotland.
There is little that can be done to treat an animal infected with squirrel pox as they will almost always succumb to the disease.2
However, there are some things that can be done to help out red squirrels, both in their protected environments and in your local area. This includes:
- Reporting sightings of infected red squirrels to the relevant authority so they can be alerted to a potential new outbreak
- Cleaning and disinfecting garden items (such as outdoor furniture and bird feeders) if you have regular squirrel visitors
To manage the grey squirrel population, it is now illegal to release or introduce grey squirrels into any wild habitat in the UK, especially into areas of protected red squirrel habitats. Other efforts include “humane” methods of trapping and shooting grey squirrels. These activities are considered to be a necessity by some and are highly contained and controlled by law.
How do you get squirrel pox?
You cannot contract squirrel pox from coming into contact with a squirrel whether they are showing signs of squirrel pox or not.
Is there a vaccine for squirrel pox?
Developing a squirrel pox vaccine is the latest strategy that is being considered to control the threat of squirrel pox to red squirrels. There is no effective vaccine that is routinely deployed at present as vaccinating wild animals is more complex than vaccinating pets, owing to their evasiveness and the unknown, and potentially harmful, side effects of a new vaccine.
How common is squirrel pox?
Squirrel pox has been active in almost every squirrel population south of Northern Scotland. In an area of an outbreak, most red squirrels in that area will contract the virus and perish in a short time.
How is squirrel pox diagnosed?
Squirrels can be diagnosed with the disease based on their physical appearance, typically presenting with prominent ulcers and scabs. If you spot a squirrel showing signs of the disease, it is advisable that you contact the relevant local wildlife authority.
How can I prevent squirrel pox?
Squirrel pox is hard to prevent in wild squirrel populations as the virus can be carried by, and spread to, any individual squirrel. To help prevent the disease, conservationists, forest rangers and members of the public can report sightings of sick squirrels and deter grey squirrels from entering areas where they may spread squirrel pox.
Who is at risk of squirrel pox?
Squirrel pox does not affect humans or any domestic animal species. The disease is isolated to the wild squirrel population, though symptoms and death usually only occurs in the dramatically declining red squirrel population.
When should I see a doctor?
Even though you cannot contract squirrel pox from coming into contact with a squirrel, it's always best to wash your hands, clothes or any other surfaces that a wild animal has touched as they can carry other disease-causing viruses and bacteria.
You should see your doctor if you have any concerning new skin lesions or rashes appearing after contact with a squirrel, as this could be a sign of another disease. This includes the rare condition called leprosy. You can be at risk of infection if you have come into close contact with a squirrel (such as by handling one), as squirrels carry the bacteria that causes leprosy.
Squirrel pox is a big problem for conservationists in the UK. The disease is painful and causes major suffering in infected red squirrels. It has devastated the UK’s red squirrel population, an important species of the UK’s native wildlife. The current efforts to prevent the spread of the virus, and the red squirrels' UK-wide extinction, have been marginally successful. However, the last squirrel pox-free population of red squirrels in the Scottish Highlands will also succumb to an outbreak if more efforts are not employed. As a member of the public, you can contribute to the protection of red squirrels in your local area by learning and being aware of the situation and what to do if you ever come across a squirrel with the squirrel pox virus.
- Gurnell J, Wauters LA, Lurz PWW, Tosi G. Alien species and interspecific competition: effects of introduced eastern grey squirrels on red squirrel population dynamics. Journal of Animal Ecology. 2004;73(1): 26–35. https://doi.org/10.1111/j.1365-2656.2004.00791.x.
- Tompkins DM, Sainsbury AW, Nettleton P, Buxton D, Gurnell J. Parapoxvirus causes a deleterious disease in red squirrels associated with UK population declines. Proceedings of the Royal Society of London. Series B: Biological Sciences. 2002;269(1490): 529–533. https://doi.org/10.1098/rspb.2001.1897.
- Collins LM, Warnock ND, Tosh DG, McInnes C, Everest D, Montgomery WI, et al. Squirrelpox virus: assessing prevalence, transmission and environmental degradation. PLOS ONE. 2014;9(2): e89521. https://doi.org/10.1371/journal.pone.0089521.
- Bruemmer CM, Rushton SP, Gurnell J, Lurz PWW, Nettleton P, Sainsbury AW, et al. Epidemiology of squirrelpox virus in grey squirrels in the UK. Epidemiology & Infection. 2010;138(7): 941–950. https://doi.org/10.1017/S0950268810000816.