Transmission of Borrelia miyamotoi sensu lato relapsing fever group spirochetes in relation to duration of attachment by Ixodes scapularis nymphs

Nicole E.Breuner, Marc C.Dolan, Adam J.Replogle, Christopher Sexton, Andrias Hojgaard, Karen A.Boegler, Rebecca J.Clark, Lars Eisen
Ticks and Tick-borne Diseases, Volume 8, Issue 5, August 2017, Pages 677-681.


Borrelia miyamotoi sensu lato relapsing fever group spirochetes are emerging as causative agents of human illness (Borrelia miyamotoi disease) in the United States. Host-seeking Ixodes scapularis ticks are naturally infected with these spirochetes in the eastern United States and experimentally capable of transmitting B. miyamotoi. However, the duration of time required from tick attachment to spirochete transmission has yet to be determined.

We therefore conducted a study to assess spirochete transmission by single transovarially infected I. scapularis nymphs to outbred white mice at three time points post-attachment (24, 48, and 72 h) and for a complete feed ( > 72–96 h). Based on detection of B. miyamotoi DNA from the blood of mice fed on by an infected nymph, the probability of spirochete transmission increased from 10% by 24 h of attachment (evidence of infection in 3/30 mice) to 31% by 48 h (11/35 mice), 63% by 72 h (22/35 mice), and 73% for a complete feed (22/30 mice).

We conclude that
(i) single I. scapularis nymphs effectively transmit B. miyamotoi relapsing fever group spirochetes while feeding,
(ii) transmission can occur within the first 24 h of nymphal attachment, and
(iii) the probability of transmission increases with the duration of nymphal attachment.


I thank the authors for stating transmission can occur in 24 hours and that transmission increases with attachment time.  

At first I thought I’d posted this before; however, in this study, No evidence of infection with or exposure to B. mayonii occurred in mice that were fed upon by a single infected nymph for 24 or 48 h. The probability of transmission by a single infected nymphal tick was 31% after 72 h of attachment and 57% for a complete feed.”

In essence the newer study found greater evidence of infection in shorter transmission times.  

Transmission time research, similarly to geographical maps of tick populations, has been used against patients for decades. Please read all transmission time studies with healthy skepticism, realizing many patients have become infected in under the oft quoted 24-72 hours. Thankfully, the CDC is now telling doctors to treat patients empirically, without waiting for test results, if they suspect tick borne illness. Bob Giguere of IGeneX states a case of a little girl who went outside to play about 8:30a.m. and came inside at 10:30 with an attached tick above her right eye. By 2 o’clock, she had developed the facial palsy. At the hospital she was told it couldn’t be Lyme as the tick hadn’t been attached long enough. They offered a neuro-consult…..(not treatment) Borrelia Burgdorferi (Bb) and Borrelia Miyamotoi (Bm) can both be transmitted by the same hard-bodied (ixodid) tick species, Bm is put with the relapsing fever group – normally transmitted by soft-bodied ticks.  Bm  may cause severe disease, including meningoencephalitis. The most common clinical manifestations of B. miyamotoi infection are fever, fatigue, headache, chills, myalgia, arthralgia, and nausea. Symptoms of B. miyamotoi infection generally resolve within a week of the start of antibiotic therapy. B. miyamotoi infection should be considered in patients with acute febrile illness who have been exposed to Ixodes ticks in a region where Lyme disease occurs. Because clinical manifestations are nonspecific, etiologic diagnosis requires confirmation by blood smear examination, PCR, antibody assay, in vitro cultivation, and/or isolation by animal inoculation. Antibiotics that have been used effectively include doxycycline for uncomplicated B. miyamotoi infection in adults and ceftriaxone or penicillin G for meningoencephalitis.