Abstract
The recent range expansion of human babesiosis in the northeastern United States, once found only in restricted coastal sites, is not well understood. This study sought to utilize a large number of samples to examine the population structure of the parasites on a fine scale to provide insights into the mode of emergence across the region. 228 B. microti samples collected in endemic northeastern U.S. sites were genotyped using published Variable number tandem repeat (VNTR) markers. The genetic diversity and population structure were analysed on a geographic scale using Phyloviz and TESS, programs that utilize two different methods to identify population membership without predefined population data. Three distinct populations were detected in northeastern US, each dominated by a single ancestral type. In contrast to the limited range of the Nantucket and Cape Cod populations, the mainland population dominated from New Jersey eastward to Boston. Ancestral populations of B. microti were sufficiently isolated to differentiate into distinct populations. Despite this, a single population was detected across a large geographic area of the northeast that historically had at least 3 distinct foci of transmission, central New Jersey, Long Island and southeastern Connecticut. We conclude that a single B. microti genotype has expanded across the northeastern U.S. The biological attributes associated with this parasite genotype that have contributed to such a selective sweep remain to be identified.
Highlights
Human babesiosis due to Babesia microti was first recognized on Nantucket Island nearly 50 years ago [1], and a few years later the first cases of Lyme arthritis were described from Old Lyme, Connecticut [2]
Samples from Nantucket (N) and Cape Cod (CC) have significant amounts of population differentiation between each other and each of the other geographic groups. (Table 2) In contrast, there is no evidence of any population differentiation between samples from New Jersey (NJ), Long Island (LI), Connecticut (CT) and Rhode Island (RI)
Our analysis provides data to help reconstruct the processes that have led to the current epidemic population structure of B. microti in northeastern US
Summary
Human babesiosis due to Babesia microti was first recognized on Nantucket Island nearly 50 years ago [1], and a few years later the first cases of Lyme arthritis were described from Old Lyme, Connecticut [2]. Both infections were found to be transmitted by the deer tick (Ixodes dammini; north American clade of I. scapularis), which had started to be locally recognized as a human-biting pest [3]. Expansion of one lineage of Babesia microti [HKG, PJM, KW, VB], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
