Comparative survey of Ixodes scapularis and tick-borne disease risk in two Lyme disease-endemic regions of New Jersey

Blacklegged ticks (Ixodes scapularis Say, Acari: Ixodidae) are the primary vectors of several emerging infectious diseases in the Northeastern United States. In New Jersey, this species was thought to be restricted to the southern part of the state until 1992-1993, when a dramatic increase in Lyme disease (LD) cases was recorded in northern NJ. However, studies throughout the 1990s found that I. scapularis ticks were far more common and more likely to be infected with Borrelia burgdorferi, the principal agent of LD, in the southern part of the state. Since this time, reports of LD, as well as other I. scapularis-borne diseases, have continued to mount in northern NJ. Yet due to a lack of regular surveillance in this region, it is unclear whether this concentration of human cases is reflective of tick and pathogen prevalence. We have modified a multiplex qPCR assay that simultaneously detects four pathogens of emerging public health importance—Borrelia burgdorferi, Borrelia miyamotoi, Anaplasma phagocytophilum and Babesia microti—in I. scapularis ticks. Tested ticks were collected over the course of four years from sites in the northern county of Hunterdon and southern county of Monmouth. Our findings reflect a dramatic increase in the prevalence of ticks infected with B. burgdorferi in Hunterdon as compared to Monmouth. Additionally, we provide evidence for the elevated risk of coinfection by multiple tick-borne pathogens in Hunterdon County. These data highlight the need for large-scale tick-borne disease surveillance in areas threatened by the expansion of I. scapularis.