Hard Tick Relapsing Fever (Borrelia miyamotoi)

Hard tick relapsing fever is caused by the bacteria Borrelia miyamotoi.

This bacterium is different from Borrelia burgdorferi and Borrelia mayonii which cause Lyme Disease.  Borrelia miyamotoi is one of several species that cause a relapsing fever type of illness.  Borrelia miyamatoi is found in blacklegged (deer) ticks and transmitted by tick bite.  Larvae, nymphs and adults of the blacklegged tick may all be infected because this pathogen is transmitted from adult females to their eggs and subsequent offspring (larvae). In Wisconsin, studies have found that 0-8% of the nymphs of Ixodes scapularis may be infected with Borrelia miyamotoi (Barbour et al. 2009).  Research suggests that the adults will have similar rates of infection.

Several cases have been identified in Wisconsin residents (Jobe et al. 2016) including at least one human case identified in a non-traveler as of 2017.

A recent report (Gugliotta et al. 2013) in the New England Journal of Medicine, identified a patient with meningoencephalitis as a probable result of infection with Borrelia miyamotoi.  A second report (Krause et al. 2013) in the same journal also identified several patients with symptoms and serology that indicated infection causing illness had occurred. “The most common clinical manifestations of B. miyamotoi infection are fever, fatigue,. miyamotoi infecti headache, chills, myalgia, arthralgia, and nausea. Symptoms 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.” (Krause et al. 2015)