Borrelia miyamotoi is a bacterium (germ) that can be spread by tiny, infected black-legged (deer) ticks. These bacteria have only recently been discovered as a cause of some human illness.
Borrelia miyamotoi was identified in black-legged ticks in New England in 2001, and has also been found in these ticks in the upper Midwest and in similar ticks in California, Europe and Russia.
Like Lyme disease, Borrelia miyamotoi is spread by the bite of an infected black-legged tick. These ticks in Massachusetts can also carry the germs that cause babesiosis, human granulocytic anaplasmosis and Powassan virus. Black-legged ticks are capable of spreading more than one type of germ in a single bite.
Young ticks (nymphs) are most active during the warm weather months between May and July. Adult ticks are most active during the fall and spring but will also be out searching for a host any time that winter temperatures are above freezing.
It is not yet known how common this disease is in Massachusetts. Results from a recent study suggest that this is an infrequent cause of illness occurring during the late spring and summer peak tick season.
Human infections with B. miyamotoi were first described in 2011 in Russia. Most of the patients had fever, headache, and muscle aches. Symptoms similar to those of Lyme disease, such as the erythema migrans rash (bull’s-eye rash), arthritis or facial palsy were uncommon. Information from cases in the United States is similar, and all reported patients recovered.
Infection with Borrelia miyamotoi can be treated with two weeks of antibiotics.