Know Your Vector: Asian Longhorned Ticks

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- [Narrator] Asian Longhorn Ticks are a recently introduced invasive species that were first discovered in New Jersey in 2017.

Since then, they have been found in patches across the Eastern United States, including 16 Pennsylvania counties.

Given this rather disjunct distribution, it is likely that increased survey efforts will find them in other areas as well.

Asian Longhorn Ticks preferentially feed on ungulates such as deer, cattle, horses, and goats.

Infestations on these animals can be extremely high, to the point of causing physical damage and allowing secondary infections to take hold.

Only a few human bites have been reported, despite some areas having extremely dense infestations of thousands of Asian Longhorn Ticks.

So while human bites are possible, Asian Longhorn Ticks will likely pose the greatest threat to wildlife and farm animals.

Asian Longhorn Ticks are brown and inornate, they have festoons along the posterior abdomen, making them somewhat similar in appearance to Brown Dog ticks.

Asian Longhorn Ticks can be distinguished from Brown Dog ticks based on the shape of the basis capituli in the palps.

In Asian Longhorn Ticks, the basis capitili are rectangular and the palps extend laterally beyond it.

In Brown Dog Ticks, the basis capituli are hexagonal and extend laterally beyond the palps.

While Asian Longhorn Ticks are found most frequently on ungulates and Brown Dog Ticks are found most frequently on dogs and other canids, Asian Longhorn Ticks have been found on dogs and Brown Dog Ticks have been found on deer.

So knowing the host can help guide identification but isn't definitive.

Two other Haemaphysalis species occur in Pennsylvania, including the Rabbit Tick, Haemaphysalis Leporispalustris.

Rabbit Ticks are found almost exclusively on rabbits, but may occasionally be found on other hosts like dogs.

Distinguishing Asian Longhorn Ticks, like the one pictured here, from Rabbit Ticks requires microscopic examination.

To summarize, Asian Longhorn Ticks are considered a newer invasive species discovered in the state of New Jersey in 2017.

As of March, 2022, they have been identified in 17 states and 16 counties in Pennsylvania.

Similarity and appearance to other Haemaphysalis species found in Pennsylvania can make identification difficult.

Knowing the host can sometimes help with identification.

Although they do not seem to be attracted to humans they pose a great risk to ungulates causing infestations in wildlife herds and farm animals resulting in physical damage, infections, and disease.