Voles are small rodents, often visually confused with common house mice, though they are generally stouter with shorter tails and ears. These animals occupy a wide range of habitats, from grasslands and forests to gardens and agricultural fields, placing them in frequent proximity to human activity. As with many wild mammals, voles can act as natural reservoirs, meaning they carry pathogens without showing symptoms of the disease themselves. This establishes them as a potential source for zoonotic diseases, which are illnesses transmissible from animals to humans.
Hantavirus The Primary Concern
Hantavirus is one of the most serious pathogens associated with voles, specifically certain strains found across Europe and Asia. Voles, such as the Bank Vole (Myodes glareolus), are the reservoir for Puumala virus, which causes a milder disease known as Nephropathia Epidemica (NE). This illness is a form of Hemorrhagic Fever with Renal Syndrome (HFRS) that presents with flu-like symptoms and kidney impairment. Other voles can carry the Tula orthohantavirus, which has low pathogenicity to humans.
The most severe hantavirus illness in the Americas is Hantavirus Pulmonary Syndrome (HPS), but this is primarily carried by New World rodents like the deer mouse, not voles. The main transmission risk is the inhalation of aerosolized virus particles. These particles become airborne when dried droppings, urine, or saliva from an infected vole are disturbed, such as during sweeping or cleaning out a shed. Once inhaled, the virus can infect the lungs, leading to severe respiratory failure (HPS) or affecting the kidneys (NE and HFRS).
Other Bacterial and Parasitic Infections
Voles are known to harbor several significant bacterial pathogens, including those responsible for Tularemia and Leptospirosis. Tularemia is caused by the bacterium Francisella tularensis, and voles are considered a key amplifier of the bacteria, especially during periods of high population density. Humans can contract Tularemia through direct contact with an infected vole or its carcass, or through the bite of an infected tick or deer fly that has fed on the rodent. This bacteria is highly infectious and can also be contracted by inhaling dust contaminated with the excreta of sick or dead animals, a risk often heightened during farming or landscaping activities.
Leptospirosis is caused by spiral-shaped bacteria of the genus Leptospira, which can be found at high prevalence rates in some vole species. Infected voles shed the bacteria through their urine, contaminating environmental sources like water and soil. Human infection typically occurs when contaminated water or soil comes into contact with broken skin, the eyes, or mucous membranes. While often presenting with flu-like symptoms, Leptospirosis can progress to cause severe illness, including kidney failure and liver damage.
Pathways of Disease Spread
Pathogens move from voles to humans through three main categories of exposure. The first pathway is aerosolization, where dried excreta containing viruses or bacteria become airborne dust that is then inhaled. This mechanism is the primary route for Hantavirus infection and is also a documented means of contracting Tularemia.
The second pathway is direct contact, which occurs through handling a live or dead vole, or contact with contaminated materials that enter the body through cuts or mucous membranes. Bites from an infected vole can also directly transmit pathogens. This highlights the importance of never handling wild rodents without heavy-duty protective gloves.
The final major pathway is vector transmission, where an intermediate organism carries the pathogen from the vole to a human. Voles can be hosts for fleas, ticks, and mites that are capable of transmitting diseases like Tularemia.
Preventing Exposure and Safe Cleanup
The most effective way to prevent exposure is through exclusion, which involves sealing all potential entry points into homes, garages, and storage sheds. Voles can squeeze through surprisingly small openings, so any gaps larger than a quarter-inch should be sealed using materials like cement or metal mesh. Removing attractants, such as pet food stored outdoors, and clearing dense vegetation or debris piles near the foundation also discourages voles from nesting close to human dwellings.
When dealing with areas contaminated by vole droppings or urine, safe cleanup procedures must be strictly followed to avoid aerosolizing the pathogens. Before beginning, the area should be ventilated by opening doors and windows for at least 30 minutes, and personal protective equipment, including rubber or plastic gloves, should be worn. Never sweep or vacuum rodent waste, as this action stirs up dust and releases virus particles into the air.
Cleanup Procedure
The cleanup process requires careful disinfection and disposal:
- Soak droppings and urine with a disinfectant solution (one part household bleach to ten parts water) and allow it to sit for at least five minutes to neutralize pathogens.
- Wipe up the saturated material using paper towels.
- Immediately place the paper towels into a tightly sealed plastic bag for disposal.
- Mop or sponge hard surfaces with the disinfectant solution, and wash any contaminated clothing in hot water.