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North Carolina (NC) has been experiencing a recent surge in human Lyme disease (LD) cases. Understanding the distribution of tick-borne diseases necessitates understanding the distribution of the ticks that transmit their causative pathogens. Unfortunately, in NC, knowledge on tick distribution is outdated. In this manuscript, we report the results of a state-wide entomologic survey conducted in 42 NC counties by flagging/dragging from spring 2018 to summer 2023.Ixodes scapularisnymphs and adults were screened forBorrelia burgdorferi(the causative agent of LD) and four other tick-borne bacterial pathogens (Anaplasma phagocytophilum,B. mayonii,B. miyamotoi, and Babesia microti) by the Centers for Disease Control and Prevention (CDC). Consistent with current data on human LD cases incidence and distribution, results of this study indicated a range expansion ofI. scapulariswith higher tick densities andB. burgdorferiinfection prevalence now occurring in the Blue Ridge Mountains province of western NC. Temporal analysis ofI. scapularispresence data indicated that this shift is fairly recent (about 10 years). Finally, in the Blue Ridge Mountains we detected a northeast-to-southwest gradient inI. scapularistick andB. burgdorferiinfection prevalence suggesting that this trend is driven by a spread of the northern cladeI. scapularisticks into NC from southwestern Virginia, along the Appalachian Mountains. Other pathogenic bacteria detected inI. scapularisticks includedB. miyamotoiandA. phagocytophilum, that were limited to the Blue Ridge Mountains.These results have important public health implications, including the need for enhanced tick surveillance, updated clinical awareness, and targeted public education in newly affected areas. 

Chiggers are larval mites that pose a significant health risk globally via the spread of scrub typhus. However, fundamental studies into the bacterial microbiome in North America have never been considered. In this investigation, chiggers were collected in the wild from two locally common rodent host species (i.e.,Sigmodon hispidusandPeromyscus leucopus) in three different ecoregions of North Carolina (NC), United States to investigate the composition of their bacterial communities, including potential pathogens. DNA was extracted from the chiggers, and the V3-V4 regions of the bacterial 16S rRNA gene were sequenced using next-generation sequencing (NGS). Alpha diversity metrics revealed significant differences in bacterial diversity among different collection counties. Beta diversity metrics also revealed that bacterial communities across counties were significantly different, suggesting changes in the microbiome as the environment changed. Specifically, we saw that the two western NC collection counties had similar bacterial composition as did the two eastern collection counties. In addition, we found that the chigger microbiome bacterial diversity and composition differed between rodent host species. The 16S rRNA sequence reads were assigned to 64 phyla, 106 orders, 199 families, and 359 genera. The major bacterial phylum was Actinobacteria. The most abundant species were in the generaCorynebacterium,Propionibacterium, class ZB2, andMethylobacterium. Sequences derived from potential pathogens within the generaOrientiaandRickettsiawere also detected. Our findings provide the first insights into the ecology of chigger microbiomes in the US. Further research is required to determine if the potential pathogens found detected in chiggers are a threat to humans and wildlife.