As if it isn’t bad enough with native ticks carrying Lyme disease, Anaplasmosis, Ehrlichia and Rickettsia, it looks like another tick has entered the USA to further complicate the situation. For the first time in 80 years, a new hard tick is front and center: the Asian longhorned tick (ALT) or Haemaphysalis longicornis, which is also called the bush tick or cattle tick.
The first it was seen was by a woman shearing her sheep in western New Jersey—she found thousands of them on the sheep. Once the CDC got involved, they identified that other collections of ticks found in the USA included the Asian longhorned ticks back in 2013. By the end of 2018, sightings of these ticks had occurred in nine states: Pennsylvania, New York, Connecticut, Maryland, Arkansas, North Carolina, Virginia, West Virginia and New Jersey.
The longhorn tick thrives in temperate, humid climates, thick with forest and moist with regular precipitation. Preferred temperature ranges between 53-104 degrees Fahrenheit, but the ticks don’t tolerate dehydration.
A recent National Geographic report (https://tinyurl.com/ycm69uku) suggested that the Asian longhorned tick is adaptable and likely to spread throughout the continental United States and southern Canada with the right climatic conditions.
In other parts of the world in its range of Eastern Asia, New Zealand and Australia, these ticks carry deadly diseases. And, they contribute to blood loss, which is significant for livestock producers, with potential similar impact on horse health. As yet, active disease transmission by these ticks has not been identified, but the research of their impact is just getting started.
The females are able to reproduce asexually through cloning without a need to mate—this is called parthenogenesis. Each female can lay up to 2,000 eggs at a time, all females, making it nearly impossible to eradicate them [Townsend, L. Asian Longhorned Tick: Challenges from an Invasive Ixodid Tick. Equine Disease Quarterly, Oct 2018, vol. 27, no. 4]. Once engorged with blood, these sesame-seed sized (3-4 mm long) ticks fill to pea size. And, even without blood meals, the ticks are able to survive up to a year. The USDA is spearheading a National Asian Longhorned Tick Stakeholder Group to research, monitor and define longhorned tick locations throughout the USA.
It is important to counsel horse owners about this potential vector for disease and advise them how to monitor and remove ticks safely from their horses.
In sheep, the ticks prefer to attach to the ears and around the eyes. A useful reference for tick removal is found at https://www.aphis.usda.gov/publications/animal_health/fs-longhorned-tick.pdf.