Characteristics of Hard Tick Relapsing Fever Caused by Borrelia miyamotoi, United States, 2013-2019

Emerg Infect Dis. 2023 Sep;29(9):1719-1729. doi: 10.3201/eid2909.221912.

Abstract

Borrelia miyamotoi, transmitted by Ixodes spp. ticks, was recognized as an agent of hard tick relapsing fever in the United States in 2013. Nine state health departments in the Northeast and Midwest have conducted public health surveillance for this emerging condition by using a shared, working surveillance case definition. During 2013-2019, a total of 300 cases were identified through surveillance; 166 (55%) were classified as confirmed and 134 (45%) as possible. Median age of case-patients was 52 years (range 1-86 years); 52% were male. Most cases (70%) occurred during June-September, with a peak in August. Fever and headache were common symptoms; 28% of case-patients reported recurring fevers, 55% had arthralgia, and 16% had a rash. Thirteen percent of patients were hospitalized, and no deaths were reported. Ongoing surveillance will improve understanding of the incidence and clinical severity of this emerging disease.

Keywords: Borrelia miyamotoi; Ixodes scapularis; United States; bacteria; characteristics; emerging infectious diseases; hard tick relapsing fever; tick-borne infections; ticks; vector-borne infections; zoonoses.

Publication types

  • Review

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • Borrelia* / genetics
  • Child
  • Child, Preschool
  • Female
  • Fever
  • Humans
  • Infant
  • Ixodes*
  • Ixodidae*
  • Male
  • Middle Aged
  • Relapsing Fever* / diagnosis
  • Relapsing Fever* / epidemiology
  • United States / epidemiology
  • Young Adult

Supplementary concepts

  • Borrelia miyamotoi