Squirrels, like almost all wild mammals, host a variety of parasitic organisms. A parasite lives on or in a host, deriving nutrients at the host’s expense. Understanding the types of organisms squirrels carry is important for minimizing potential risks to people and pets in shared environments.
Categorizing Squirrel Parasites
The organisms that live on or inside squirrels are divided into two main groups: ectoparasites and endoparasites. Ectoparasites are external, residing on the surface of the squirrel’s body, skin, or fur. This category includes common pests like fleas, ticks, mites, and lice, which feed on blood or skin debris.
Fleas and the American dog tick are frequently found on squirrels, particularly those living in wooded habitats. Mites and lice also inhabit the fur, sometimes causing irritation or hair loss on the host animal. The larval stage of the botfly, sometimes called a “warble,” develops beneath the squirrel’s skin, creating a noticeable lump with a breathing hole.
Endoparasites live inside the squirrel, often inhabiting the digestive tract or other internal organs. These include helminths, which are worm-like organisms such as nematodes (roundworms) and cestodes (tapeworms). Nematodes are commonly identified in squirrels and reside in the intestines.
Protozoans are single-celled endoparasites that can infect the digestive system. Examples found in squirrels include Giardia species and Coccidia. The presence of these internal organisms is confirmed through the examination of fecal matter.
Transmission Pathways to Humans and Pets
Parasites primarily move from squirrels to humans and pets through indirect transmission via vectors or environmental contamination. Ectoparasites like fleas and ticks can detach and seek a new host, such as a dog, cat, or human. These pests can transmit bacterial diseases, such as Lyme disease from ticks, or tularemia and plague from fleas, during a bite.
The environment becomes contaminated when squirrels deposit waste containing endoparasite eggs or other pathogens. Droppings and urine can contain bacteria like Salmonella and Leptospira, which cause salmonellosis and leptospirosis. Contact with contaminated soil or water where squirrels nest or feed can lead to infection in people and domestic animals.
Ingestion of microscopic eggs is a pathway for internal parasite transmission, especially for roundworms. If a pet or person accidentally touches squirrel feces and then transfers the eggs to their mouth, an infection can occur. This pathway requires careful hygiene precautions to prevent the eggs from entering the body.
Another transmission route is direct contact with a squirrel suffering from a fungal infection. Ringworm, a skin condition, can be transmitted by touching the infected animal’s skin or hair.
Recognizing Signs of Parasitic Infection
Signs of heavy parasitic load are visible through observation of the squirrel’s physical appearance and behavior. Patchy or thinning fur, often accompanied by excessive scratching, indicates external infestation by mites or fleas. The presence of warbles, which are large lumps on the body, clearly indicates botfly larvae developing beneath the skin.
A heavily infected squirrel may exhibit noticeable lethargy, moving slowly and appearing less alert than usual. In rare cases, internal parasites that migrate to the brain, such as certain species of roundworm, can cause neurological symptoms. This may manifest as erratic behavior, loss of coordination, or circling, which can sometimes be mistaken for rabies.
Safe Practices for Coexisting with Squirrels
The best way to reduce the risk of parasite exposure is to discourage squirrels from inhabiting areas close to human and pet activity. Homeowners should seal all potential entry points into attics, garages, and crawl spaces, using materials like metal mesh or caulk to prevent nesting. Trimming tree branches away from the roofline also removes a common access route for squirrels.
Pet owners should ensure that dogs and cats receive veterinarian-recommended year-round preventative treatments for fleas and ticks. These treatments help break the cycle of vector-borne transmission, protecting both the pet and the human household. It is also important to avoid feeding squirrels, as this encourages them to frequent the area and increases the concentration of their waste.
General hygiene practices are an effective barrier against indirect transmission. This includes:
- Always wearing gloves when handling bird feeders.
- Gardening in areas frequented by wildlife.
- Immediately securing or removing any spilled bird seed.
- Wearing protective gloves if a sick or deceased squirrel must be moved, and thoroughly washing hands afterward.
These simple precautions help maintain a safe distance and minimize the chance of exposure to parasites or pathogens.