Can Pesky House Mice Spread Lyme Disease?

Author: Mosquito Squad of Greater Washington DC

You may have read stories before on this blog talking about the link between ticks, Lyme Disease, and white-footed mice. These stories may have piqued your curiosity about other species of rodents, especially pesky house mice that like to take up residence in our homes. Since we are entering into the peak season for nymph ticks, and very soon,  into the fall when the weather will be growing colder, and house mice will be looking for places to stay warm, now is a great time to become familiar with tick/mouse activity.

Mice & Lyme Disease

White-footed mice do exceptionally well in the habitat of the Northeast US and other similar places because of the urbanization of old farmland.  Open woodlots and brushy areas make ideal living conditions for white-footed mice and ticks.

Although Lyme Disease is not as prevalent in some US states, other tick-borne diseases are.  Tularemia, Rocky Mountain Spotted Fever, and other infections are often prevalent in places Lyme Disease is not.  Shrews, voles, rabbits, chipmunks and other small rodents will fill a similar role as white-footed mice in these regions when available.

When an adult female tick needs to lay her eggs, she looks for a location that will have a temperature warm enough in winter to allow her eggs to survive.  White-footed mice build nests in burrows, stumps, brush piles, buildings and in the abandoned nests of other small animals and birds.  These nests provide concealment for them from predators and warmth in the winter.

When an adult female tick lays her eggs in the nest of a white-footed mouse, she is providing both protection and a good start for the next generation.  When hatched into larvae in the spring and early summer, these ticks will take their first blood meal from the closest available small animal, which is usually the white-footed mouse.  Tick larvae are not infected with Lyme Disease when born.  Their first chance to be infected is when they take their first blood meal from the mice.  As these larvae ticks grow and need a second blood meal to develop into their third life stage as nymph ticks, the mice will often serve as hosts to that meal also.

Recent Studies of Mice & Lyme Disease

Studies show that 80-90% of all white-footed mice are infected with the Lyme bacteria.  When you consider the number of larvae and nymph ticks that take their blood meal from white-footed mice, you can easily see why the infection rate is so high.  Ticks will often have to bite more than one host for a blood meal to get an adequate supply of blood so that they can grow into their next life cycle stage.  If one larva or nymph tick is infected with Lyme Disease, the infection will usually be transmitted to any of the mice they bite.  Ticks that bite an infected mouse have a very high likelihood of becoming infected themselves and further transmitting the disease.  As ticks become larger, they need larger mammals and birds for their blood meal.  This is how Lyme Disease is transmitted to raccoons, foxes, opossums, birds, and other small mammals.  Deer serve as hosts for adult ticks because of their size allows them to have enough blood to provide many adult ticks their blood meal to lay eggs.

For mice that do not frequent open woodlots and brushy areas, there is little chance of them being exposed to ticks.  No contact with ticks means no Lyme infection.  This is the primary reason that Lyme Disease is rare or non-existent in mice that seek shelter and warmth in your home.  As these or any mice spend time in your yard and tick habitat, it’s possible they can become infected, if bitten by an infected tick.  House mice have not been studied to determine if they contract Lyme Disease in certain situations, but there is no reason to think they would be immune.  It’s likely they are not a vector for Lyme Disease because they simply don’t spend as much time in tick habitat as other rodents.

Contact Mosquito Squad Today!

As you can see, the circumstances that lead to Lyme Disease are diverse and complex.  With so many vectors, hosts and reservoirs responsible for the disease, researchers are a long way off from knowing how the disease continues to spread. Rather than wait for science to provide a solution, there are effective solutions now such as barrier sprays and tick tube implementation for your yard. Contact Mosquito Squad of Greater Washington DC now to discuss our tick barrier spray and tick tube program that will protect your yard all season long.