First Case of Tick that Transmits Lyme Disease Found in Montana

A tick removed from a hunting dog in Dawson County was confirmed to be the blacklegged tick (Ixodes scapularis, also called the deer tick), which is the primary tick that carries and transmits Lyme disease in the eastern United States. The geographic range of I. scapularis has historically been in the eastern and midwestern part of the country, but its range has slowly been moving north and west. This is the first time this important tick species has been documented in Montana, and the discovery has important health implications for those working and recreating outdoors.

Blacklegged Ticks are much smaller than the ticks we're used to seeing in Montana; adults are only about the size of a sesame seed. They are most active in the spring, summer and fall when daytime temperatures are above freezing.

Blacklegged ticks get Lyme disease when they feed on an infected animal such as a mouse or vole. Although deer may serve as hosts for these ticks, they don't become infected, and ticks can't acquire the disease by feeding on deer. However, deer and other animals probably help move ticks into new areas.

Blacklegged ticks are usually associated with forested habitats. However, wooded riparian corridors found along many of Montana's rivers and streams may provide suitable habitat for this species, allowing it to migrate into the open plains. It's unknown whether blacklegged ticks can survive Montana's winters, or if they need to rely on the movement of host animals to enter the state. Warmer, shorter winters combined with more people recreating outdoors means there might be more occurrences of this tick in Montana.

Lyme disease is a bacterial infection that people can get when they are bitten by an infected blacklegged tick. It's the most common disease vectored by an arthropod in the United States. In the western part of the United States, a closely related tick (Ixodes pacificus, the western blacklegged tick) also transmits Lyme disease. Early symptoms of Lyme disease include a characteristic circular rash at the bite site and fever, headache, and fatigue. If left untreated, the infection may affect the joints, heart, and nervous system.

It's important for people recreating and working outdoors to be aware of ticks and the diseases they may carry. Tick season in Montana generally runs from late spring through fall, with peak activity in May and June. The best way to prevent a tick bite is to protect yourself when you're outside.

• Wear long-sleeved shirts and long pants, tucking your pants into your socks.
• Steer clear of overhanging vegetation along trails; ticks often climb to the top of vegetation in search of hosts to latch onto by waving their legs in a behavior called "questing".
•  Use EPA-recommended insect/tick repellents. A list can be found on this website: https://www.epa.gov/insect-repellents/find-repellent-right-you.
• Perform regular tick checks.
• Wash clothes and dry in the hottest setting.

If you find a tick embedded in your skin, use thin-tipped tweezers to remove it. Ticks have barbs on their mouthparts, which make them difficult to remove. If the mouthparts break off and remain in the skin, they may be a source of irritation and lead to an infection. Using the tweezers, grasp the tick as close to the skin as possible and remove it with a slow, steady pull away from the skin. Try to avoid crushing the tick and its mouthparts. Disinfect the skin with alcohol or soap and water.

Blacklegged ticks need to be attached for more than 24 hours before they can transmit Lyme disease. If you get a fever or a rash, call your doctor. The U.S. Centers for Disease Control doesn't recommend testing ticks for diseases because tests are often inaccurate. If you'd like to have your tick identified to species, you can place it in a hard container and send it to the Schutter Lab at Montana State University.

-by MSU Extension Service -