Ticks can carry diseases caused by bacteria, viruses, and parasites. In the United States, blacklegged ticks, lone star ticks, American dog ticks, and Rocky Mountain wood ticks are the main disease-transmitting ticks.
The illness you may face depends on the tick species, where you were exposed, and how long the tick fed.
If you find a tick attached, remove it promptly, record when and where the exposure happened, and watch for symptoms for several weeks.
Many tickborne diseases cause similar signs, so your healthcare provider may consider the tick, your location, symptoms, and laboratory testing together.
Ticks spread diseases when they feed and introduce a pathogen through their saliva. The National Center for Emerging and Zoonotic Infectious Diseases explains that ticks transmit bacteria, viruses, and parasites while feeding, even when you do not feel the bite.
Identify the Major Disease-Transmitting Ticks
Different tick species occupy different parts of the United States and carry different pathogens. Identifying the tick can help your healthcare provider estimate risk, though you should not wait for perfect identification before seeking care.
Blacklegged and Deer Ticks
The blacklegged tick includes the eastern blacklegged tick (Ixodes scapularis) and western blacklegged tick (Ixodes pacificus).
People often call I. scapularis the deer tick because deer support adult ticks, although immature ticks commonly feed on small mammals and birds.
Blacklegged ticks are especially important in the Northeast, Mid-Atlantic, Upper Midwest, and Pacific Coast. They can transmit Lyme disease, anaplasmosis, babesiosis, Powassan virus, and certain relapsing fever bacteria.
Lone Star Ticks
The lone star tick (Amblyomma americanum) is widespread across the Southeast, South, and parts of the Midwest and Mid-Atlantic.
A white spot on the adult female’s back can help distinguish it from other ticks. Lone star ticks can transmit ehrlichiosis, tularemia, and Heartland and Bourbon viruses.
Their bites may also trigger alpha-gal syndrome, an immune reaction associated with sensitivity to mammalian meat and other products.
American Dog Ticks and Wood Ticks
The American dog tick (Dermacentor variabilis), sometimes called a wood tick, is found widely east of the Rocky Mountains and in parts of the Pacific Northwest.
It can transmit Rocky Mountain spotted fever, tularemia, and occasionally cause tick paralysis. The name “wood tick” can also refer to other Dermacentor species, so appearance alone may not identify the tick reliably.
A photograph, preserved specimen, or professional identification may provide more useful information.
Rocky Mountain Wood Ticks
The Rocky Mountain wood tick (Dermacentor andersoni) lives mainly in mountainous areas of the western United States and Canada. It can transmit Rocky Mountain spotted fever, tularemia, Colorado tick fever, and bacteria associated with tick paralysis.
Risk varies by elevation, habitat, season, and local tick activity.
The National Park Service’s tickborne disease guidance notes that disease risk depends on whether a capable tick vector is present in your area.
Illnesses Linked to Each Tick Species
Knowing which ticks carry diseases can help you recognize patterns, yet no single tick appearance proves that infection occurred.
Symptoms may overlap, and some infected people do not develop a noticeable rash.
Lyme Disease, Anaplasmosis, and Babesiosis
Blacklegged ticks transmit Lyme disease, caused primarily by the bacterium Borrelia burgdorferi. Early symptoms may include fever, chills, headache, fatigue, muscle aches, and an expanding rash called erythema migrans.
Untreated infection can later contribute to joint pain, nerve problems, or arthritis. The same ticks can transmit anaplasmosis, formerly called human granulocytic ehrlichiosis.
Fever, headache, chills, fatigue, and muscle aches are common, and severe illness can occur. Babesiosis is caused by protozoa that infect red blood cells.
It can produce fever, chills, fatigue, and anemia, with greater risk of severe disease for older adults and people without a functioning spleen.
Ehrlichiosis, Tularemia, and Alpha-Gal Syndrome
Lone star ticks commonly transmit ehrlichiosis, a bacterial illness that can cause fever, headache, fatigue, muscle aches, and sometimes a rash.
Early medical evaluation matters because severe disease can develop. Ticks can transmit tularemia, caused by Francisella tularensis.
Symptoms vary by the route of infection and may include fever, an ulcer at the bite site, swollen lymph nodes, or pneumonia. A lone star tick bite may trigger alpha-gal syndrome, also called red meat allergy.
You may develop delayed hives, stomach symptoms, or a serious allergic reaction after eating mammalian meat or products containing alpha-gal.
Rocky Mountain Spotted Fever and Colorado Tick Fever
Rocky Mountain spotted fever, or RMSF, can be transmitted by American dog ticks, Rocky Mountain wood ticks, and other regional species.
Early symptoms often include fever, headache, and muscle aches. A rash may appear later, so do not wait for one before contacting a clinician.
Colorado tick fever, or CTF, is a viral illness spread mainly by Rocky Mountain wood ticks. Fever, chills, headache, fatigue, and muscle aches may begin several days after a bite.
Powassan Virus Disease and Relapsing Fever
Blacklegged ticks can transmit Powassan virus, which causes Powassan virus disease.
Many infections are mild or symptom-free, yet severe cases can cause encephalitis or meningoencephalitis, with headache, fever, confusion, seizures, or difficulty coordinating movement.
Certain ticks transmit relapsing fever, a bacterial infection marked by recurring episodes of fever.
The specific tick and bacteria vary by region, so your exposure history helps guide diagnosis and treatment.
What to Do After Finding a Tick
A tick bite does not guarantee infection. Prompt removal lowers the time available for transmission.
Save useful details, monitor your health, and seek medical guidance when symptoms appear.
Remove the Tick and Record Exposure Details
Use fine-tipped tweezers to grasp the tick as close to your skin as possible. Pull upward with steady pressure, then clean the bite area and your hands with soap and water or rubbing alcohol.
Do not twist, crush, burn, smother, or coat the tick with petroleum jelly. Note the date, location, and likely exposure area.
You can place the tick in a sealed container or take a clear photograph. Routine tick testing does not replace medical evaluation.
Watch for Symptoms That Need Medical Care
For several weeks, watch for fever, chills, headache, fatigue, muscle aches, joint pain, or a new rash.
An expanding erythema migrans rash strongly suggests Lyme disease, while a severe headache, confusion, breathing difficulty, weakness, or rapidly worsening illness requires urgent care.
Tick paralysis can cause weakness or paralysis that gradually moves upward through the body. Removing the attached tick often leads to recovery, yet breathing or swallowing problems require emergency treatment.
Treatment, Testing, and Prevention
The type of treatment depends on the suspected disease. Clinicians may prescribe antibiotics such as doxycycline for several bacterial tickborne diseases. Antibiotics do not treat viral illnesses such as Powassan virus disease or Colorado tick fever.
Testing is often more useful after symptoms develop. Early results can be negative.
Wear long sleeves and light-colored clothing to prevent future bites. Stay on cleared trails.
Check your body and pets after outdoor activity. Shower soon after coming indoors.
Apply an EPA-registered repellent containing DEET as directed. Use appropriate tick control products for pets.
