The lone star tick (Amblyomma americanum) is a species historically associated with the southeastern and eastern United States. However, in recent years, this aggressive, human-biting tick has been expanding its range northward, reaching into the Upper Midwest, including Minnesota. This expansion brings new public health challenges, most notably the risk of alpha-gal syndrome (a severe allergy to red meat) and other tickborne diseases.

This report provides a comprehensive overview of the lone star tick’s presence in Minnesota, the factors driving its expansion, the associated health risks, and guidance for prevention and tick submission.

1. Identification and Characteristics

The lone star tick is a medium-sized tick that can be distinguished from other common Minnesota ticks, such as the blacklegged (deer) tick and the American dog (wood) tick.

• Adult Females: Easily recognizable by a distinct single yellowish-white spot or “lone star” on the center of their back (scutum) [1].
• Adult Males: Pale brown with mottled black markings on their back, lacking the prominent white spot [1].
• Behavior: Unlike blacklegged ticks, which are slow feeders, lone star ticks are known to be very aggressive biters that actively pursue human hosts [2]. They can bite humans in all three of their active life stages (larva, nymph, and adult) [3].
• Habitat: They prefer wooded areas with dense, low-lying vegetation and brushy habitats [1].

2. Presence and Range Expansion in Minnesota

While the blacklegged tick and American dog tick are the most common species in Minnesota, the lone star tick is increasingly being reported in the state.

Current Status in Minnesota

As of recent years, the lone star tick is considered rare in Minnesota and is not yet widely established across the state [4]. However, the number of reports has been steadily increasing. A map from the Minnesota Department of Health documented 103 confirmed lone star ticks reported in the state as of December 2024 [5].

The Minnesota Board of Animal Health notes that there have been rare and sporadic reports of lone star ticks in the state, but they are not widely established [6]. However, the tick is becoming more common in summers that follow a warm winter [1].

Drivers of Northward Expansion

The lone star tick’s historical range in the 1750s covered much of the eastern U.S., but it receded as forested land and white-tailed deer populations decreased [2]. Since the 1940s, conservation efforts have allowed deer populations to rebound, enabling the tick to repopulate its historical range and push further north [2].

Scientific studies and surveillance indicate that the lone star tick’s range is expanding northward into the Upper Midwest at a rate of 35 to 55 kilometers per year [7]. This expansion is primarily driven by:

1. Climate Change: Warming temperatures and milder winters make northern regions, including Minnesota, more hospitable for the tick’s survival and reproduction [8] [9].
2. Host Movement: The expansion of white-tailed deer populations, which serve as a keystone host for adult lone star ticks, facilitates their spread into new areas [2] [10]. Birds and small mammals also transport immature ticks [10].

3. Health Risks and Tickborne Diseases

The lone star tick is a vector for several significant diseases and medical conditions. Its arrival in Minnesota introduces health risks that were previously uncommon in the state.

Alpha-Gal Syndrome (Red Meat Allergy)

The most notable and increasingly common condition associated with the lone star tick is alpha-gal syndrome (AGS).

• Mechanism: When the tick feeds, it can transfer a sugar molecule called alpha-gal into the person’s body. In some individuals, this triggers an immune system reaction [11].
• Symptoms: Subsequently, when the person consumes mammalian meat (beef, pork, lamb, venison) or products derived from mammals (like dairy or gelatin), they experience an allergic reaction. Symptoms usually appear 2 to 6 hours after eating and can include hives, itching, swelling of the face/lips/throat, stomach cramps, nausea, vomiting, and in severe cases, life-threatening anaphylaxis [11] [12].
• Impact: AGS is a unique food allergy because it is acquired from an environmental exposure (a tick bite) rather than being present from birth. The rising incidence of lone star ticks in Minnesota has led to a corresponding emergence of AGS cases in the state [11].

Other Diseases Transmitted

In addition to AGS, the lone star tick can transmit bacterial and viral pathogens, including:

• Ehrlichiosis: Caused by Ehrlichia chaffeensis and Ehrlichia ewingii. Symptoms include fever, headache, chills, muscle pain, nausea, and confusion [1] [13].
• Tularemia: A rare bacterial disease that can cause skin ulcers, swollen lymph glands, and fever [1] [4].
• Heartland Virus and Bourbon Virus: Emerging viral diseases that can cause fever, fatigue, and lower white blood cell counts [10] [14].

Note: The lone star tick does not transmit Lyme disease, which is primarily spread by the blacklegged (deer) tick [1].

4. Surveillance and Citizen Science

Monitoring the spread of the lone star tick is crucial for public health in Minnesota. Various organizations are actively tracking tick populations.

• Metropolitan Mosquito Control District (MMCD): The MMCD conducts tick surveillance in the seven-county Twin Cities metro area using mammal collections and tick dragging [1]. They also offer a free tick identification service for residents [1].
• Minnesota Department of Health (MDH): The MDH monitors human cases of tickborne diseases and tracks tick distribution. They encourage the public, veterinarians, and livestock producers to submit unusual ticks for identification [6].
• Citizen Science (Sanford Health & Marshfield Clinic): The “Tick Inventory via Citizen Science (TICS)” study allows residents across Minnesota to submit ticks they find on themselves or their pets. This program helps researchers identify rare species, track the spread of ticks like the lone star tick, and assess the risk of tickborne diseases [15].

5. Prevention Guidelines

To protect against lone star ticks and other tick species in Minnesota, public health officials recommend the following preventative measures [1] [4] [11]:

Prevention Strategy	Recommended Actions
Avoid Tick Habitats	Stick to the center of trails when in wooded or brushy areas. Avoid walking through tall grass and dense underbrush.
Protective Clothing	Wear light-colored clothing to make ticks easier to spot. Wear long sleeves and pants, and tuck pants into socks to prevent ticks from crawling up your legs.
Use Repellents	Apply EPA-registered insect repellents containing DEET, picaridin, or IR3535 to exposed skin. Treat clothing and gear with products containing 0.5% permethrin.
Perform Tick Checks	Conduct thorough, full-body tick checks after spending time outdoors. Pay special attention to hidden areas like the scalp, behind the ears, under the arms, and behind the knees.
Shower After Outdoors	Showering within two hours of coming indoors can help wash off unattached ticks and provides a good opportunity to do a tick check.
Protect Pets	Use veterinarian-recommended tick prevention products on dogs and cats. Check pets for ticks daily, as they can bring ticks into the home.

Proper Tick Removal

If a tick is found attached to the skin, it should be removed promptly to reduce the risk of disease transmission:

• Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible [1].
• Pull upward with steady, even pressure. Do not twist or jerk the tick, as this can cause the mouthparts to break off and remain in the skin [1].
• After removing the tick, thoroughly clean the bite area and your hands with rubbing alcohol or soap and water [1].
• Dispose of a live tick by putting it in alcohol, placing it in a sealed bag/container, wrapping it tightly in tape, or flushing it down the toilet. Alternatively, save it in a sealed container for identification by public health authorities [1].

References [1] Metropolitan Mosquito Control District. “Tick Surveillance.” Available at: https://mmcd.org/tick-surveillance/ [2] Centers for Disease Control and Prevention. “Lone Star Tick Surveillance.” Available at: https://www.cdc.gov/ticks/data-research/facts-stats/lone-star-tick-surveillance.html [3] Northeast Regional Center for Excellence in Vector-Borne Diseases. “Lone Star Tick.” Available at: https://www.neregionalvectorcenter.com/lone-star-tick.php [4] Minnesota Department of Health. “Ticks.” Available at: https://www.health.state.mn.us/diseases/tickborne/ticks.html [5] Minnesota Department of Health. “Minnesota Lone Star Tick Reports 2023.” Available

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