by MICHAEL D’ESTRIES
Much to the chagrin of everyone who loves the great outdoors, a new species of exotic tick has officially set up residence in the United States.
The New Jersey Department of Agriculture announced last week that the longhorned tick, a species native to China, Japan and Australia has successfully survived the New Jersey winter and may be spreading throughout the state.
The tick was first discovered in the U.S. last August after a N.J. farmer walked into a county health office covered in ticks. She reported that she had been shearing the single sheep on her property when she noticed multitudes of the four-legged blood suckers crawling up her arms. A closer inspection by health officials revealed something even more frightening: nearly 1,000 ticks moving throughout her clothing.
“What she didn’t know was her entire clothing, pants and everything, they were covered in ticks,” Tadhgh Rainey, division manager of Hunterdon County Division of Health Services, told NPR.
More unusual than this sight, however, was that officials couldn’t identify the species of tick clinging to her clothes. A team of experts later determined it to be Haemaphysalis longicornis, never before seen in the U.S., and plaguing livestock that had never ventured outside the country.
A grim discovery
A description of the team’s visit to the tick-plagued farm sounds like something straight out of a horror movie.
“Investigation of the Hunterdon property in early October revealed a large number of ticks both on the sheep and throughout the paddock,” the scientists shared in a new study published in the Journal of Medical Entomology. “The ticks in the paddock were so numerous that they crawled on investigators’ pants soon after setting foot inside. The sheep was supporting hundreds of ticks, including all three active life stages (larva, nymph, adult). Although ticks were concentrated on the sheep’s ears and face, engorged ticks of all stages were readily found all over its body, including areas beneath the animal’s thick coat.”
Following a chemical treatment in September, the sheep was later declared tick-free. Visits by officials in late November found no ticks in either the paddocks or the surrounding grounds. While scientists were hopeful that the state’s cold winter temperatures might kill off any remaining populations, the longhorned tick has one evolutionary advantage that gave them pause.
“This tick overwinters in the ground,” Rainey told NJ.com. “No tick does that.”
Sure enough, when entomologists visited the site again this spring, they were disappointed to discover that the longhorned tick had successfully overwintered. They added that, based on this evidence, the new species has quite possibly “become established in the state.”
Divide and conquer
Besides its ability to burrow underground to avoid death from freezing temperatures, the longhorned also has some other characteristics that put a frightening spin on this discovery. For one thing, the tick reproduces asexually, rapidly increasing in population by cloning itself and laying thousands of eggs. The nymphs and adults also tend to “swarm” their prey, with recorded observations of hundreds of ticks hanging from their hosts like “bunches of grapes.”
“Only one tick is needed to start a population, and they can grow to high numbers quickly,” Andrea M. Egizi, Ph.D., research scientist at the Tick-Borne Disease Laboratory at Rutgers University and senior author on the report, told Entomology Today. “They are not limited by the need to find mates, which can be difficult in a small population.”
While the longhorned ticks tested at the New Jersey sheep farm came back negative for known tick-borne disease, such as Lyme disease or borreliosis, it may be only a matter of time before they become carriers. The tick is already a known transmitter of diseases in its native ranges.
If there’s any good news to come out of this discovery, it’s that the ticks apparently don’t have a taste for human, preferring instead to swarm livestock and wildlife. Unfortunately, this also makes it easier for them to spread. In late April, federal and state wildlife officials combing the area around the farm where the infestation was first discovered found a longhorned tick on a white-tailed deer, a foreboding sign for early containment efforts.
A call for vigilance
In an effort to track the extent of the tick’s spread, N.J. Department of Agriculture officials are asking people to report infestations of unusual ticks on pets or livestock. Figuring out whether or not they’re exotic or native species may be another challenge altogether.
“Like deer ticks, the nymphs of the longhorned tick are very small (resembling tiny spiders) and can easily go unnoticed on animals and people,” they said in a statement.
The group plans to continue surveillance of potentially impacted species throughout the rest of the year.