LB 22-226 - CANCELLED - First established population of the Asian longhorned tick (Haemaphysalis longicornis) in Ohio, USA

Background/Question/Methods:

We describe the first established Asian longhorned tick (Haemaphysalis longicornis; ALT) population in Ohio, USA at the leading edge of westward range expansion for this exotic tick. Established populations of ALT were first recognized in the U.S. in 2017, but retrospective analyses of archival specimens suggest there may have been multiple introductions beginning as early as 2010. ALTs have now been reported in at least 17 states and are expanding rapidly. They are especially good colonizers in part because of their ability to reproduce through parthenogenesis, which is unique from our native North American ticks. ALT range expansion has severe consequences for the livestock industry as these ticks can cause fatalities from intense infestations or the transmission of tick-borne pathogens. We responded to a report of heavily infested cattle with a loss of 3 heifers and 1 bull to collect tick specimens, identify species, and determine whether tick-borne pathogens were also present.

Results/Conclusions:

A total of 9,287 ticks were collected and all were identified as ALT. Field-collected ticks were positive for Anaplasma phagocytophilum (8/97; 8.25%), the causative agent for human granulocytic anaplasmosis, but negative for Borrelia burgdorferi sensu stricto, Rickettsia rickettsii, Ehrlichia chaffeensis, and Theileria orientalis. The livestock producers and landowners used mechanical and chemical approaches recommended for native ticks to control the ALT population on site, but ALT were active again the following spring warranting continued monitoring of tick and tick-borne pathogen population dynamics. The introduction of an exotic tick species capable of transmitting emerging foreign pathogens such as Theileria orientalis and contributing to the enzootic cycle of endemic pathogens presents a significant ecological challenge. Furthermore, naive hosts in areas of ALT invasion can suffer greater pathology than hosts in regions where this tick is endemic. Since ALTs reportedly infest a wide variety of wildlife in the U.S., they may also impact local ecological communities. As ALTs continue to expand in the U.S., we will need further surveillance studies to characterize their evolving role in human and animal health, as well as effective options for management.