Pathogen Coinfections Harbored by Adult <i>Ixodes scapularis</i> from White-Tailed Deer Compared with Questing Adults Across Sites in Maryland, USA

Abstract

The blacklegged tick, <i>Ixodes scapularis</i>, can acquire and transmit tick-borne pathogens (TBPs) responsible for diseases such as human granulocytic anaplasmosis (<i>Anaplasma phagocytophilum</i> [ANPH]), babesiosis (<i>Babesia microti</i> [BABE]), Lyme borreliosis (<i>Borrelia burgdorferi sensu</i> lato [BBSL]), and the relatively novel relapsing fever-like illness, <i>Borrelia miyamotoi</i> (BMIY) disease in the northeastern United States. Coinfections with these pathogens are becoming increasingly more common in <i>I. scapularis</i> and their hosts, likely attributed to their shared enzootic cycles. Urban habitats are favorable to host species such as white-tailed deer (<i>Odocoileus virginianus</i>) and these ungulates are known to be important to <i>I. scapularis</i> for reproduction and dispersal in North America. To understand the relationship between TBPs, white-tailed deer, and <i>I. scapularis</i>, we sampled eight sites across central Maryland collecting <i>I. scapularis</i> using standard tick dragging/flagging methods and retrieved others from deer carcasses. Pathogenic TBP species in each tick were determined using qPCR. In total, 903 adult ticks (deer: <i>n</i> = 573; questing: <i>n</i> = 330) revealed landscape-level prevalence of ANPH (27.8%), BABE (1.3%), BBSL (14.6%), and BMIY (0.8%) as singular infections overall. However, secondary coinfections of ANPH and BBSL were highest (9.9%) in ticks feeding from deer while associations of BBSL and BABE (4.2%) were highest in questing ticks. Results from this study provide evidence suggesting that adult <i>I. scapularis</i> acquire pathogenic species through phenologically associated host use, and thus, subsequent infections found in adults may provide insights into coinfection relationships.