Spatial and temporal patterns of the emerging tick-borne pathogen Borrelia miyamotoi in blacklegged ticks (Ixodes scapularis) in New York

F Keesing,D J Mchenry,R S Ostfeld,M H Hersh

doi:10.1186/s13071-020-04569-2

Abstract

Borrelia miyamotoi, a bacterium that causes relapsing fever, is found in ixodid ticks throughout the northern hemisphere. The first cases of human infection with B. miyamotoi were identified in 2011. In the eastern USA, blacklegged ticks (Ixodes scapularis) become infected by feeding on an infected vertebrate host, or through transovarial transmission. We surveyed B. miyamotoi prevalence in ticks within forested habitats in Dutchess County, New York, and identified possible reservoir hosts. To assess spatial variation in infection, we collected questing nymphal ticks at > 150 sites. To assess temporal variation in infection, we collected questing nymphs for 8 years at a single study site. We collected questing larval ticks from nine plots to estimate the amount of transovarial transmission. To evaluate potential reservoir hosts, we captured 14 species of mammal and bird hosts naturally infested with larval blacklegged ticks and held these hosts in the laboratory until ticks fed to repletion and molted to nymphs. We determined infection for all ticks using quantitative polymerase chain reaction. The overall infection prevalence of questing nymphal ticks across all sites was ~ 1%, but prevalence at individual sites was as high as 9.1%. We detected no significant increase in infection through time. Only 0.4% of questing larval ticks were infected. Ticks having fed as larvae from short-tailed shrews, red squirrels, and opossums tended to have higher infection prevalence than did ticks having fed on other hosts. Further studies of the role of hosts in transmission are warranted. The locally high prevalence of B. miyamotoi in the New York/New England landscape suggests the importance of vigilance by health practitioners and the public.Graphical abstract

Highlights

First described from ticks in Japan [9], Borrelia miyamotoi is a member of a group of bacteria that cause relapsing fever
B. miyamotoi had been found in ticks from across the northern hemisphere, its role as a human pathogen was recognized only in 2011, when 46 patients in Russia tested positive for B. miyamotoi infection [24]
For the 51 sites we sampled in both years, there was no strong correlation in infection prevalence across years (Kendall’s τ = 0.154)

Summary

Introduction

First described from ticks in Japan [9], Borrelia miyamotoi is a member of a group of bacteria that cause relapsing fever. A congener of Borrelia burgdorferi, the pathogen that causes Lyme disease, Borrelia miyamotoi has been identified in B. miyamotoi had been found in ticks from across the northern hemisphere, its role as a human pathogen was recognized only in 2011, when 46 patients in Russia tested positive for B. miyamotoi infection [24]. Relapsing fever occurred in 11% of these patients and 5% developed a bulls-eye rash (erythema migrans) [24]. In 2013, the first patients in the USA were identified, with cases in New Jersey and Massachusetts [10, 17]. The role of B. miyamotoi in human cases of tick-borne illness is being more broadly investigated (e.g. 7, 32)

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Results

Conclusion