Rutgers Investigators Create Pictorial Key for Accurate Identification of Asian Longhorned Tick

The presence of the Asian longhorned tick in the United States exposes a need for surveillance measures and actions to prevent disease transmission before its onset in humans and other animal species.

And now to promote active surveillance, investigators from Rutgers University have partnered with other scientists to create a visual guide that will allow for easy identification of the Asian longhorned tick. The ticks are native to eastern Asia, and reproduce asexually, therefore it is imperative to control the tick before it spreads through the country and leads to the transmission of dangerous infections.

The tick has been found across the eastern United States, but it has been difficult to determine how widespread the Asian longhorned ticks have become because they are nearly identical to the rabbit tick and the bird tick, which are both native to the country and mostly harmless to humans.

"To begin to understand the threat posed by Asian longhorned ticks in the United States, we need to know the full extent of its distribution," Andrea Egizi, PhD, a visiting professor at Rutgers' Center for Vector Biology and a research scientist with the Monmouth County Tick-borne Disease Program, and lead author of the study, said in a statement. "We made this key so that researchers across the country have an easier way to identify them."

The guide, created by the team from Rutgers Center for Vector Biology, makes it easy for anyone with a strong enough microscope to correctly identify the tick from the harmless North American ticks, as well as similar species native to Central America.

The guide was published in ZooKeys and identifies distinguishing characteristics of the Asian longhorned tick such as 2 triangular, hornlike spurs that appear on its mouth. The details are visible on scanning electron microscopy images taken by the team collaborators.

The investigators’ guide enables researchers to distinguish all life stages of the 4 similar species of ticks that may be encountered in North America. Before this all-encompassing key, researchers would have to compare the morphology of the 4 species through the use of different keys from around the world.

The investigators are hopeful that the key will make it easy to distinguish between the species and have a positive role in the efforts to map the distribution of the Asian longhorned tick in the United States, as well as reveal potential risks to the general population.

The investigators also think the finding will improve the understanding of the biology and ecology of native ticks to North America, which have not been studied well in the past.

The Asian longhorned tick was identified in New Jersey through collaboration between Rutgers and the Monmouth County Tick-borne Disease Program in 2017. The first tick was discovered in Hunterdon County on pet sheep, and the finding was confirmed by the US Department of Agriculture’s National Veterinary Services Laboratory.

The tick was detected again in New Jersey in April of 2018, proving that the pest can survive the winter. Since then, the tick has been detected in Arkansas, Connecticut, Maryland, New York, North Carolina, Pennsylvania, Virginia, and West Virginia

"We now know that the Asian longhorned tick has been present in New Jersey since at least 2013, but that first discovery, found on a dog in Union County, was initially mistaken for a rabbit tick," Dina Fonseca, PhD, director of the Rutgers Center for Vector Biology and an investigator on the study, said in the statement. "We are hoping this visual guide will help us identify and control the expansion of this tick."