Asian Longhorned Tick in the U.S.: A New Tick Species Spreading Rapidly
A new tick species is spreading in the United States.
It can reproduce rapidly and carry disease.
But the full risk to humans is still unclear.
The Asian longhorned tick (Haemaphysalis longicornis) is an emerging tick species in the United States that continues to expand its geographic range.
This is where a new public health concern is still unfolding.
This spread includes the Northeast, where Lyme disease is already common.
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First identified on sheep in New Jersey in 2017, the tick has since spread to multiple states, including Arkansas, Connecticut, Kentucky, Maryland, North Carolina, New Jersey, Pennsylvania, Tennessee, West Virginia, Virginia, and New York.
This spread has happened quickly—and continues to expand.
This tick is part of a broader pattern of expanding tick populations in the United States.
Public health officials are actively monitoring this emerging tick species.
Where Has the Asian Longhorned Tick Been Found?
How quickly is this tick spreading?
Since its discovery, the Asian longhorned tick has been identified across at least 11 U.S. states, raising concerns about continued expansion.
This spread has occurred over a relatively short period of time.
Its ability to reproduce rapidly contributes to its success. Female ticks can lay thousands of eggs without mating.
What Diseases Can the Asian Longhorned Tick Carry?
This is where the concern becomes more serious.
The Asian longhorned tick has been shown to carry:
- Borrelia species (associated with Lyme disease)
- Heartland virus
- Powassan virus
According to the <:contentReference[oaicite:0]{index=0}>, the full public health risk of this tick in the United States remains unknown.
This uncertainty makes early awareness critical.
Has This Tick Bit Humans in the United States?
When was the first human case identified?
The first reported human bite in the United States occurred in 2018 in a 66-year-old man from Yonkers, New York (Wormser et al., 2019).
Although the patient did not become ill, the case led to the identification of the tick species in New York.
This is where detection depended on a human exposure.
Subsequent environmental sampling found ticks in nearby parks and grassy areas, including locations with both sun and partial shade.
What Are the Unknown Risks?
This is where questions remain unanswered.
Researchers are still investigating whether the Asian longhorned tick can efficiently transmit U.S.-based pathogens to humans.
Concerns include:
- Transmission of emerging viral infections such as Heartland virus
- Potential spread of Powassan virus
- Possible links to red meat allergy following tick bites
The long-term public health impact is still evolving.
Why Is This Tick Different?
The Asian longhorned tick has several features that distinguish it from other ticks:
- Ability to reproduce without mating (parthenogenesis)
- Rapid population expansion
- Adaptability to different environments
These characteristics increase the potential for widespread exposure.
Clinical Takeaway
The Asian longhorned tick is spreading in the United States, including regions where Lyme disease is already common.
Early identification and awareness are essential as this emerging risk continues to evolve.
As new tick species emerge, recognizing unfamiliar risks early becomes increasingly important.
Related Reading
- Infected deer ticks moving into New York City
- When should you worry about ticks in your neighborhood?
- High prevalence of Babesia microti in Suffolk County
References
- <:contentReference[oaicite:1]{index=1}>. (2018). Asian longhorned tick spreading rapidly in the U.S. Retrieved from https://www.cdc.gov/media/releases/2018/p1129-tick-spreading-widely.html
- Wormser, G. P., McKenna, D., Piedmonte, N., et al. (2019). First recognized human bite in the United States by the Asian longhorned tick, Haemaphysalis longicornis. Clinical Infectious Diseases.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
