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Southeastern Cooperative Wildlife Disease Study

Haemaphysalis longicornis

Surveillance for the exotic tick Haemaphysalis longicornis (longhorned tick) in the Eastern United States

Nymph of H longicornis
Nymph of H. longicornis (left) compared to Amblyomma americanum (lone star) nymph (right). Courtesy of Graham Hickling (UT)
H longicornis
H. longicornis collected from white-tailed deer

Background

The longhorned tick, also known as the cattle tick or bush tick, is native to eastern Asia. The tick has become invasive in several countries including Australia and New Zealand where it is an important parasite of cattle. It is also of concern to the cattle industry as it is a vector of Theileria orientalis. Also, some infested animals may develop very high tick burdens. Within the native range, this tick species is infected with or is known to transmit numerous pathogens to people and animals.

There are some life history traits of H. longicornis that enhance its invasive potential. It has a broad geographic range and nymphs and adults are able to enter diapause (suspended development) or overwinter in colder environments.  Further, H. longicornis has a wide host range including humans, cattle, dogs, horses, and small ruminants as well as a wide variety of wild and feral species such as carnivores, cervids, feral pigs, rodents, and several bird species. Finally, some populations of H. longicornis are capable of asexual reproduction (parthenogenesis), in which adult female ticks can produce fertile eggs without contact with male ticks. Therefore, a single female tick introduced to a new area can start a population which is what has happened in New Zealand, Australia and now the United States.

This exotic Asian tick species first was confirmed in the United States in November 2017 following its collection from a domestic sheep and its caregiver in Hunterdon County, New Jersey. Beginning that fall, SCWDS and multiple other organizations began collaborative surveillance for the tick to determine if it had become established. By Spring 2018 the tick was confirmed to still be present in New Jersey and soon after was noted in new geographic regions and on new hosts. 

How can you help?

SCWDS is conducting regional surveillance for this tick through collaborations with various agencies. One method of detection is by the collection of ticks from deer and bears (road-killed, hunter killed, or other harvested). We are also working with several wildlife rehabilitation centers to collect ticks from fawns and other wildlife. All of these ticks are being submitted to SCWDS for identification and future inclusion in studies on the population genetics of H. longicornis and pathogen testing.

If you are able and willing to collect ticks for this surveillance project, please contact us at myabsley@uga.edu.

Current distribution and host range of H. longicornis in the United States

Publicly available records of H. longicornis have been collated and the map of the distribution is available here. This map is interactive and can show reports at the county level and can be easily sorted by user-defined region, state, host or year.

Plot.ly Link

Click here or the image above to go to the interactive map.

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