Grey Squirrel Diseases
- Jared Crawford
- Sep 26
- 7 min read
Exposing Squirrel Diseases in Urban and Wild Populations: Uncovering the Hidden Dangers

Grey squirrels can be seen running under woodland canopies or darting through metropolitan parks. Squirrels and the environments they dwell in are both impacted by a hidden world of diseases that lurk behind their colourful antics.
These health hazards, which range from bacterial infections to parasitic infestations, can affect both urban and rural areas and can occasionally endanger people and animals.
To safeguard your house, garden, and local wildlife, you must first understand these diseases. This is a clear, thorough reference to squirrel diseases, their consequences, and responsible grey squirrel problem-solving techniques using expert pest control.
Why Squirrel Diseases Matter

In the United Kingdom, grey squirrels (Sciurus carolinensis) are tenacious, versatile, and common. However, they are vulnerable to several health problems, such as:
Parasitic infestations like mange and intestinal worms
Viral infections such as squirrelpox
Bacterial diseases including leptospirosis and tularaemia
Fungal infections like ringworm
In addition to harming squirrels, these conditions have the potential to disturb ecosystems, have an impact on native red squirrel populations, and, in rare instances, spread zoonotic diseases to people or pets.
Did you know?
More than 40 parasites can live in a single grey squirrel, and infections connected to severe illnesses may be found in their nests.
Act now: For a safe and legal inspection and treatment of squirrel-related hazards, get in touch with Apex Pest Control or another BPCA-certified pest management specialist.
Parasitic Infections: Hidden Threats Inside and Out

Internal Parasites: Worms in the Gut
Parasitic worms such as roundworms (Ascaris spp.) and tapeworms (Taenia spp.) flourish inside a squirrel's digestive tract, frequently going unnoticed until symptoms manifest. By stealing nutrition, these parasites lead to:
Weight loss and malnutrition
Digestive issues or intestinal blockages
Lethargy and reduced activity
These worms are acquired by squirrels by the consumption of polluted food or faeces-contaminated nesting materials. Particularly during the winter, severe infestations can weaken squirrels and reduce their chances of surviving.
External Parasites: Fleas, Lice, and Mites

The thick fur of a squirrel serves as a refuge for external parasites such as:
Fleas (Ctenocephalides felis, Orchopeas howardi): These carry bacteria like Bartonella and jump between hosts.
Lice (Enderleinellus spp.): They cling to hair, causing intense itching.
Mites (Sarcoptes scabiei, Demodex): These trigger skin damage and hair loss.
The constant scratching of infested squirrels causes open sores and subsequent illnesses. Reduced foraging, dehydration, and anaemia are all consequences of high parasite burdens.
Mange: A Microscopic Menace

What Causes Mange?
Sarcoptes scabiei mites, which burrow into a squirrel's skin and induce inflammation and intense itching, are the cause of mange. Among the symptoms are:
Patchy hair loss, starting around the head and shoulders
Crusty, thickened skin, often grey or white
Lethargy and emaciation due to disrupted foraging
To make their situation worse, mange-afflicted squirrels may rub against branches or scratch compulsively.
How Mange Spreads
Direct contact during social interactions or in shared nests is how mange is disseminated. In shared habitats, it may also have an impact on other species, like as dogs or foxes. In urban squirrel populations that are densely populated, outbreaks spread rapidly.
Spot an outbreak: Keep an eye out for bald-patched squirrels in colonies close to your house. Inform a certified wildlife rehabilitator of any encounters.
Viral Diseases: Squirrel pox and Beyond

Squirrel pox: A Devastating Threat to Red Squirrels
The poxvirus that causes squirrel pox kills native red squirrels (Sciurus vulgaris), but it usually doesn't hurt grey squirrels, which serve as carriers. Red squirrel symptoms include:
Skin ulcers around the eyes, ears, and face
Swelling and crusting of lesions
Rapid decline and death within two weeks
Grey squirrels can transmit the virus by coming into close contact with one another or by sharing surfaces, such as feeders. According to the Red Squirrel Survival Trust, red squirrel populations in England and Wales have decreased due to this disease, falling from 3.5 million in the 19th century to less than 140,000 now.
Conservation efforts: Although there is currently no widely accessible vaccine to protect red squirrels, pilot vaccination programs are in place. Reporting sightings to nearby wildlife trusts will help save red squirrels.
Other Viruses: Herpesvirus and Adenovirus
Adenoviruses, which cause respiratory or digestive problems, and herpesviruses (ScHV-1), which cause mouth ulcers or lethargy, can infect squirrels. Red squirrels are more likely to die from these infections, but grey squirrels frequently carry them without showing any signs. In the UK, several factors make red squirrel displacement worse.
Bacterial Infections: Silent but Serious

Common Bacterial Threats
Through wounds or tainted food, bacteria such as Streptococcus species and Pasteurella multocida (pasteurellosis) infect squirrels, leading to:
Abscesses and inflammation
Respiratory issues or pneumonia
Neurological symptoms like head tilt or disorientation
Because of their dense populations and exposure to human trash, urban squirrels are more vulnerable.
Tularaemia: A Rare but Potent Risk
Tularaemia is an uncommon bacterial disease that affects squirrels and is brought on by Francisella tularensis. It spreads by way of:
Direct contact with infected animals
Tick bites (Dermacentor variabilis, Amblyomma americanum)
Contaminated soil or water
Less than 200 human cases occur in the US each year, but if left untreated, tularaemia can produce serious symptoms like fever and enlarged lymph nodes. Take precautions: In wooded locations, apply bug repellent and refrain from handling dead squirrels.
Leptospirosis: A Waterborne Concern
Leptospirosis, which is caused by Leptospira interrogans, is transmitted through soil or water tainted with urine. Human symptoms include fever, aches in the muscles, and in extreme situations, damage to the kidneys or liver. Wet areas and urban parks raise the risk of transmission.
Prevention tip: To keep squirrels away from gardens, keep pet dishes clean every day and don't leave standing water there.
Lyme Disease: Squirrels as Tick Hosts

The bacterium that causes Lyme disease, Borrelia burgdorferi, can be carried by ticks (Ixodes ricinus in the UK), which are hosted by grey squirrels. In gardens and woodlands, squirrels maintain tick populations, which raises the danger of human exposure, even though mice are the main reservoirs.
Reduce tick encounters:
Clear brush piles and dense vegetation
Use squirrel-proof bird feeders
Apply tick preventives to pets
Check for ticks after outdoor activities
Rabies: Separating Fact from Fiction

According to the Animal and Plant Health Agency, the UK is regarded as rabies-free among terrestrial species, hence squirrels rarely carry the disease. In squirrels, parasites, injuries, or neurological disorders are more likely to cause erratic behaviour than rabies.
Key takeaway: Squirrels pose no significant rabies risk in the UK. Report unusual behaviour to a licensed wildlife rehabilitator for assessment.
Zoonotic Risks: Diseases That Can Spread to Humans
Squirrel-borne zoonotic diseases are rare but include:
Disease | Cause | Transmission | Human Symptoms |
Tularaemia | Francisella tularensis | Tick bites, contact with infected animals | Fever, ulcers, swollen lymph nodes |
Leptospirosis | Leptospira interrogans | Contaminated water or soil | Fever, muscle aches, kidney damage |
Salmonella | Salmonella spp. | Faecal contamination | Diarrhea, fever, cramps |
Ringworm | Fungal infection | Direct contact | Itchy, circular rash |
Stay safe:
Wear gloves when handling squirrel feeders or nests
Wash hands thoroughly after outdoor activities
Avoid direct contact with wild squirrels
Spotting Diseased Squirrels

Squirrels in good health move quickly and are vigilant. Squirrels with illnesses may show:
Lethargy or unresponsiveness
Hair loss or open sores (e.g., mange, squirrelpox)
Erratic movements like circling or stumbling
Swollen abdomen or laboured breathing
What to do: Never try to cure sick squirrels on your own. For safe, compliant handling, get in touch with your local wildlife authority or a certified wildlife rehabilitator.
Preventing Disease Transmission

Personal Hygiene
Use disposable gloves when cleaning squirrel feeders or handling traps
Wash hands with soap for 20 seconds after contact with wildlife areas
Use alcohol-based sanitisers (60% ethanol) when water isn’t available
Home and Garden Tips
Clean feeders weekly with a 10% bleach solution (1 part bleach, 9 parts water), rinse thoroughly, and air-dry
Secure bins and compost to deter squirrels
Avoid hand-feeding to reduce bite risks
Protecting Pets
Apply vet-recommended flea and tick preventives
Supervise outdoor pets to prevent squirrel interactions
Clean outdoor pet bowls daily to avoid contamination
Ecological Impacts of Squirrel Diseases

Ecosystems undergo significant changes as a result of squirrel diseases:
Red Squirrel Decline: Squirrelpox, carried by grey squirrels, has reduced red squirrel populations by over 90% in some UK regions.
Biodiversity Shifts: Disease outbreaks regulate squirrel populations, affecting seed dispersal and predator-prey dynamics.
Climate Change: Warmer climates expand parasite ranges, increasing mange and tick-borne disease risks.
Support conservation: To help red squirrels recover, protect their native habitats and notify nearby wildlife trusts of any squirrel sightings.
Wildlife Rehabilitation: A Vital Role
Each year, thousands of sick or injured squirrels are treated by licensed wildlife rehabilitators who are subject to Natural England's regulations. They:
Quarantine animals to prevent disease spread
Administer treatments like miticides for mange or antibiotics for infections
Ensure animals are fit for release or humane dispatch, per UK law
How to help:
Report sick squirrels to your local wildlife rehabilitator
Avoid feeding wildlife to reduce disease transmission
Support rehab centres with donations of supplies like linens or heat lamps
Legal and Humane Grey Squirrel Control

The Wildlife and Countryside Act of 1981 and the Invasive Alien Species Order of 2019 govern the management of grey squirrels, which are considered invasive species in the United Kingdom. Important rules consist of:
No release: It’s illegal to release trapped grey squirrels into the wild or allow them to escape.
Humane dispatch: Trapped squirrels must be humanely euthanised, adhering to the Animal Welfare Act 2006.
Licensing: Keeping grey squirrels as pets or for long-term rehabilitation requires a licence from Natural England.
Why choose professionals? BPCA-certified technicians are trained in legal, humane, and effective methods, ensuring compliance and safety.
Act now: If grey squirrels are nesting in your attic or causing damage, contact Apex Pest Control for a compliant, professional solution.
Frequently Asked Questions
Can I keep a grey squirrel as a pet in the UK?
No, unless you have a licence from Natural England or Natural Resources Wales. Keeping grey squirrels without permission is illegal.
Can I release a trapped grey squirrel?
No. Releasing grey squirrels into the wild is illegal under the Invasive Alien Species Order 2019. They must be humanely dispatched, per the Animal Welfare Act 2006.
Are squirrel-borne diseases a risk to my family?
Most squirrel diseases pose low direct risk, but ticks from nests can transmit Lyme disease in some areas. Use gloves and avoid handling wildlife.
How do I spot a squirrel infestation?
Look for scratching noises in the attics at dawn or dusk, shredded nesting materials, or chewed wires and insulation.
Why choose a BPCA-certified pest control company?
BPCA-certified technicians ensure legal, humane, and effective pest control, protecting your home and wildlife, in line with BPCA standards.
Take Control with Confidence
DIY remedies are insufficient to address grey squirrel infestations and related diseases.
Timely action yields enduring outcomes, whether it is attic damage or zoonotic hazards. For BPCA-certified, compassionate, and legally compliant solutions that are customised to meet your needs, rely on Apex Pest Control.For peace of mind and a qualified inspection, get in touch with us today.
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