Lyme disease starts when Borrelia bacteria enter your body through the bite of an infected tick. In the United States, blacklegged ticks, also called deer ticks, are the main carriers, including Ixodes scapularis in the East and north-central states and Ixodes pacificus along the Pacific Coast.
Tiny blacklegged tick nymphs most often spread Lyme disease, and they can be difficult to spot on your skin. Knowing which ticks carry Lyme disease, where they live, and what to do after a tick bite helps you act promptly and recognize possible symptoms.
The Primary Lyme Disease Vectors
Two species of blacklegged tick mainly spread Lyme disease in the United States. In Europe and Asia, related Ixodes ticks also spread Lyme disease, but different Borrelia species circulate in those regions.
Blacklegged Tick: Ixodes scapularis
The blacklegged tick, also called the deer tick, spreads Lyme disease in the eastern and north-central United States. Its range includes the Northeast, Mid-Atlantic, Wisconsin, Minnesota, and nearby states.
Adult females have dark legs and a black shield near the head, while their bodies look reddish-brown or gray after feeding. Nymphs are much smaller, about the size of a poppy seed, and they account for many human infections because you may not notice them.
These ticks carry Borrelia burgdorferi, the main Lyme disease bacterium in the United States. They may also carry other pathogens, including those that cause babesiosis and anaplasmosis.
Western Blacklegged Tick: Ixodes pacificus
The western blacklegged tick, Ixodes pacificus, spreads Lyme disease along the Pacific Coast, especially in California, Oregon, and Washington. It looks similar to the eastern blacklegged tick and can carry Borrelia burgdorferi.
Local habitat and season affect your risk. You may find these ticks in wooded areas, brush, leaf litter, and grassy edges where wildlife passes.
Lyme-Carrying Ixodes Ticks Outside the United States
Europe and Asia also have Lyme disease. The castor bean tick, Ixodes ricinus, spreads several Borrelia species in Europe, while the taiga tick, Ixodes persulcatus, spreads Lyme disease in northern and eastern Europe and Asia.
The exact tick species and Borrelia strain vary by region. If you develop symptoms after international travel, tell your clinician where and when the tick exposure happened.
Where Lyme Risk Is Highest And How Transmission Happens
Geography, habitat, tick life stage, and attachment time all affect your risk. Blacklegged ticks pick up Borrelia from wildlife and can pass it to you during a blood meal.
U.S. Regions And Outdoor Habitats
Lyme risk is highest in the eastern and north-central United States, with added risk along the Pacific Coast. Wisconsin and Minnesota have established populations of infected blacklegged ticks.
You may find ticks in wooded areas, shrubs, leaf litter, tall grass, and brushy borders. Lawns near forest edges can also have ticks, especially where leaves, vegetation, and wildlife create cover.
Why Nymphs Create A Higher Hidden Risk
Nymphs are active during warmer months and are much smaller than adults. Their size and tendency to feed on people make them easy to miss during a tick check.
An infected tick usually needs time to transmit Lyme disease, so removing the tick quickly is important. You may still need medical advice even after a brief attachment, especially if the tick was likely a blacklegged tick or you develop symptoms.
Wildlife Hosts, Deer, And Infected Ticks
Small mammals, especially mice and other rodents, carry Borrelia and infect immature ticks. White-tailed deer support many adult deer ticks and help tick populations thrive, but deer are not the main reservoir for the bacteria.
When infected ticks feed on people, they can transmit Lyme disease. Wildlife activity near your home can raise your risk even if you do not hike deep in the woods.
Ticks Commonly Confused With Lyme Vectors
Not every tick that bites you carries Lyme disease. Some species transmit other pathogens, and some cause rashes or illnesses that look like Lyme disease.
Lone Star Tick And STARI
The lone star tick, Amblyomma americanum, is common across much of the southern and eastern United States. It does not spread Lyme disease, but its bite can cause Southern tick-associated rash illness, or STARI.
STARI may cause an expanding rash after a lone star tick bite. Since the rash can look like erythema migrans, contact a clinician rather than trying to identify the illness yourself.
American Dog Tick And Rocky Mountain Spotted Fever
The American dog tick, Dermacentor variabilis, spreads Rocky Mountain spotted fever and other infections. It is larger and patterned differently from a blacklegged tick, though tick identification can be hard without magnification or expertise.
The Rocky Mountain wood tick, another Dermacentor species, spreads Rocky Mountain spotted fever in parts of the western United States. Even ticks that do not carry Lyme disease can transmit serious diseases.
Other Tick-Borne Illnesses Linked To Blacklegged Ticks
Blacklegged ticks can transmit babesiosis, anaplasmosis, and Powassan virus in addition to Lyme disease. Other ticks may spread ehrlichiosis, relapsing fever, or different pathogens depending on your region.
Tell your clinician about any tick exposure, travel, rash, and symptoms. A fever or illness after a bite may mean another infection, and some ticks can transmit more than one pathogen.
What To Do After Finding A Tick
Act calmly and remove an attached tick as soon as you find it. Make a note of when and where you found the tick, since that information can help a clinician assess your risk.
Safe Tick Removal Steps
Use fine-tipped tweezers to grasp the tick as close to your skin as possible. Pull upward with steady, even pressure.
Clean the bite area and your hands with soap and water or alcohol. Do not twist, crush, burn, smother, or cover the tick with oil or petroleum jelly.
Guidance on safe tick removal after a bite also recommends avoiding substances that can irritate the tick or skin.
Symptoms That Need Medical Advice
Watch for an expanding rash called erythema migrans, fever, flu-like symptoms, fatigue, headache, swollen lymph nodes, muscle aches, or joint pain in the days or weeks after a bite. A rash does not always form, and many people do not remember a tick bite.
Seek urgent medical care for severe headache, possible meningitis, facial weakness, fainting, chest symptoms, or heart palpitations. If your clinician suspects Lyme disease, they can decide whether testing or antibiotics are needed.
Reducing Future Tick Bites
Check your body for ticks after outdoor activity. Pay close attention to your scalp, hairline, ears, armpits, waist, groin, and behind your knees.
Shower soon after coming indoors. Wash or dry your clothing to help remove unattached ticks.
Use an EPA-registered repellent such as DEET, picaridin, or oil of lemon eucalyptus as directed. Treat clothing and gear with permethrin.
Wear light-colored clothing. Keep grass and brush trimmed around areas you use frequently.
