A study found that the climate of the eastern area of the United States is similar to the native habitat of the Asian longhorned tick in Asia and Australia, which suggests the tick will become more common in the US.
Haemaphysalis longicornis, also called the Asian longhorned tick, is the first invasive tick to emerge in the United States in approximately 80 years. The tick has been classified as a new emerging disease threat by the US Centers for Disease Control and Prevention, and now a new study has found that the Asian longhorned tick could survive in the majority of the eastern United States and the coastal Pacific Northwest.
In the study, published today in the Journal of Medical Entomology, Ilia Rochlin, PhD, an entomologist associated with the Rutgers University Center for Vector Biology, analyzed variables such as average annual rainfall and temperature from 260 locations in Asia and Australia where the tick has been previously reported, and then developed a model that would combine this data with climate data from North America to determine suitable habitats for the tick.
“The Asian longhorned tick will most likely become established in many areas of temperate United States and southern Canada,” Dr. Rochlin told Contagion® in an interview, “[W]e know that this tick species readily feeds on humans, pets, and wildlife. All these aspects increase the likelihood that the Asian longhorned tick may become a vector species transmitting some of the numerous tick-borne pathogens already circulating over much of eastern North America.”
The study results indicated that suitable areas for habitation in North America include coastal areas from eastern Canada, such as New Brunswick and Nova Scotia; down south to Virginia and North Carolina; and from southern British Columbia to northern parts of California on the west coast. The report also notes that suitable habitats were detected through inland North America from northern Louisiana to Wisconsin and into southern Ontario and Quebec, as well as Kentucky, Tennessee, and Missouri (see image).
Other parts of North America were excluded due to warmer temperatures, cold winters, or dry terrain.
According to Dr. Rochlin, while this model is a good prediction of potential habitats for the tick on a large scale, there is still not enough information to pinpoint specific locations of potential habitation. In order to predict potential habitats on the county or township level, investigators need to learn more about the biology and ecology of the tick.
While little is currently known about the biology of the tick, the vector has been known to transmit a number of serious infections to both humans and animals in Asia and Australia.
Although there have been no reports of Asian longhorned tick-to-human transmission of disease in the United States so far, Dr. Rochlin said that it is critical to learn more about this tick and its capabilities.
He explained that in East Asia, the Asian longhorned tick transmits thrombocytopenia syndrome virus, which triggers a severe fever on par with Rift Valley Fever. Additionally, the thrombocytopenia syndrome virus is closely related to the Heartland virus, which is already present in the United States and transmitted by lone-star ticks.
“Clinicians across the potential range of the Asian longhorned tick should… be on a lookout for unusual patterns of existing tick-borne diseases, or the emergence of new tick-borne pathogen[s],” Dr. Rochlin advised.
Surveillance is imperative. One of the most important ways to stop the tick from transmitting dangerous infections to humans and animals is to practice tick surveillance.
“[W]e are in dire need of comprehensive tick control strategy and new tools to carry it out, from decision-making software to environmentally friendly acaricides to effective methods for host control,” Dr. Rochlin concluded.