Borrelia miyamotoi is a tick-borne, relapsing-fever pathogen that is emerging throughout the Northern Hemisphere. Although this pathogen is widespread, the enzootic cycle has not been thoroughly described in the western United States. Despite sharing the same vector, Ixodes pacificus, as the Lyme disease agent, B. burgdorferi, there is little evidence of co-infection. We hypothesize that in western United States, B. miyamotoi has similar range to B. burgdorferi, but has different reservoirs that maintain its transmission. Unlike B. burgdorferi, B. miyamotoi can be vertically transmitted from infected female tick to progeny at high rates, but the role of vertical versus horizontal transmission remains unclear. As of now, the reservoir host and pathogen dynamics of B. miyamotoi has not been identified in California. To investigate the enzootic cycle of B. miyamotoi we sampled at potentially endemic areas for all life stage of ticks and potential small mammal reservoirs. To measure infection prevalence in samples, a quantitative real-time PCR (qPCR) and nested PCR is conducted prior to sequencing. These experiments allow us to understand a newly emergent pathogen and identify human risk areas.
Results/Conclusions
Isolates for B. miyamotoi in a potential reservoir has been identified in a species that is not known to be infected with B. burgdorferi. This gives greater importance to sampling a large variety of small mammal reservoirs that are not commonly sampled. Another niche of B. miyamotoi was confirmed with qPCR testing of higher prevalence of B. miyamotoi in blood versus tissue samples. This information is vital for sampling and screening methods in this upcoming field season. For the vector, variation of prevalence within tick life stages shows a significant increase from larval to nymphal stage, which can possibly mean the importance of horizontal transfer from a reservoir. To the extent of importance of horizontal and vertical transmission will be explored through additional data and modeling. Elucidating endemic areas, potential reservoirs and vector transmission dynamics of B. miyamotoi is critical for future public health measures in locations with multiple tick-borne diseases.