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Borrelia miyamotoi: About

Borrelia miyamotoi is a species of bacteria spread by ticks that can cause human illness in Wisconsin, although this is rare. It is spread by the deer tick, also known as the black-legged tick.

B. miyamotoi infections are most common in the Upper Midwest (including Wisconsin), the Northeast, and the mid-Atlantic states, in places where Lyme disease is common. The bacteria are most likely to be spread in July and August.

Anyone can get B. miyamotoi, but people who spend more time outdoors are at higher risk of being bitten by an infected tick. Ticks can be found in areas with woods, brush, or tall grass. Ticks are most active from May to September, but it is important to use caution year-round to prevent tick bites.

Close view of a deer tick on hand

 

B. miyamotoi is spread to humans through the bite of an infected deer tick.
  • A tick can spread B. miyamotoi within the first 24 hours of being attached to a human. It is important to remove ticks as soon as they are found to prevent illness.
  • Most humans are infected by immature ticks, called nymphs.
    Adult tick with black spot on back rests on a leaf
    • Nymphs are very small, about the size of a poppy seed. They are difficult to see, and most people may not feel their bite. This makes them harder to remove promptly.
    • Nymphs are most active during the spring and summer.
  • Adult ticks also spread B. miyamotoi.
    • Adults are much larger than nymphs, and are more likely to be found and removed before the bacteria are spread to the person.
    • Adult ticks are most active during the cooler months.
  • B. miyamotoi may be spread by larval ticks.
    • Larval ticks are even smaller than nymphs and are very unlikely to be noticed.
    • Larval ticks are most active in summer and fall.
  • Ticks can attach to any part of the body but are often found in hard-to-see areas, such as:
    • Behind the knees
    • Armpits
    • Scalp
    • In and around the ears
    • Inside the belly button
    • Groin

B. miyamotoi is preventable and treatable. Visit our Tick Bite Prevention page to learn how to prevent tick bites, and how to properly remove a tick if you are bitten.

Symptoms can show up days to weeks after being bitten by an infected tick.

Common signs and symptoms:

  • Fever
  • Chills
  • Fatigue
  • Severe headache
  • Muscle aches
  • Joint pain
Adult drinking a cup covered with blanket and a crumpled tissue on lap, holding a thermometer

B. miyamotoi can be successfully treated with the antibiotics and dosages used to treat Lyme disease. It is important to get treatment as soon as possible after symptoms start. Antibiotics commonly used for oral treatment include doxycycline, cefuroxime axetil, or amoxicillin. The following table shows the current treatment recommendations from the Centers for Disease Control and Prevention (CDC) for early stage Lyme disease in adults and children.

Age Category
Drug
Dosage
Maximum
Duration, Days
Adults
Doxycycline
100 mg, twice per day orally
N/A
10–21
Adults
Cefuroxime axetil
500 mg, twice per day orally
N/A
14–21
Adults
Amoxicillin
500 mg, twice per day orally
N/A
14–21
Children
Amoxicillin
50 mg/kg per day orally, divided into three doses
500 mg per dose
14–21
Children
Doxycycline
4 mg/kg per day orally, divided into two doses
100 mg per dose
10–21
Children
Cefuroxime axetil
30 mg/kg per day orally, divided into two doses
500 mg per dose
14–21

DHS Resources
CDC Resources
Partner Resources
B. miyamotoi is preventable and treatable. Visit our Tick Bite Prevention page to learn how to protect yourself from illnesses spread by ticks.

Questions about illnesses spread by ticks? Contact us!
Phone: 608-267-9003 | Fax: 608-261-4976

Last revised June 29, 2020