Asian tick that clones can spread fast and far in the US, study says



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"This tick can bite humans, pets, farm animals and wildlife," said Ilia Rochlin, study author and entomologist and research associate at the Center for Vector Biology at Rutgers University.

Until recently, this species was found only in China, Japan, Korea and south-east Russia, as well as parts of Australia, New Zealand and the Pacific islands. Then in 2017, the first established Asian population of longhorned ticks was discovered in New Jersey, followed by detections in Virginia, West Virginia, Pennsylvania, North Carolina and Arkansas.

Although the tick is capable of causing infectious diseases, no case of disease, both in humans and in animals, has been reported in the United States.

"There is a good chance that this tick will be widely distributed in North America," Rochlin said. "Mosquito control has been very successful in this country, but we are losing the battle against tick-borne diseases."

Unusual reproductive abilities

Dina M. Fonseca, director of the Center for Vector Biology, a Rutgers entomology professor and co-author of an earlier report published by the US Centers for Disease Control and Prevention, explained the strange ability of the Asian longhorned tick to reproduce asexually .

"These ticks are parthenogenetic, which means that females create diploid eggs (with a complete set of DNA from the mother) that develop in adults without needing the DNA of a male," she wrote in an e-mail. (Fonseca did not contribute to the new study).

Of almost 700 species of "hard" ticks – of which the Asian longhorned tick is one – only a handful is known to be parthenogenetic. "So it's a rare skill, but not exceptional," Fonseca said. This unusual method of clone creation means that it is possible for the tick to cause "massive" infestations of its hosts. "We have seen a large number of animals as much as dogs."

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One of the diseases that long-lived Asian ticks can transmit is severe fever with thrombocytopenia syndrome, a haemorrhagic disease that has recently emerged in China, South Korea and Japan, according to the previous CDC report.

This syndrome, which also causes nausea, diarrhea and muscle pain, results in hospitalization for most patients and leads to death in up to a third of those infected. That possibility is worrisome because a close relative of the disease, the Heartland virus, circulates in the Midwest and South states, Rochlin noted.

Two Asian longhorned ticks: one immature nymph or tick on the left and one adult female.
The tick can also carry other pathogens, including viruses that cause Lyme disease, ehrlichiosis and anaplasmosis, Rochlin said. Each of these diseases can lead to severe disability.
In Australia and New Zealand, the Asian longhorned tick transmitted theileriosis to cattle. Also called "bovine anemia", the disease causes lethargy, lack of appetite and, in pregnant cows, miscarriage or stillbirth. "In some regions of New Zealand and Australia, this tick can reduce dairy production by 25 percent," says the CDC report.
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"Where could I go or where could I be?"

As the tick was found in widely separated regions of the United States, Rochlin believes that "it was present in the United States for several years" and probably will gain additional space. For his new study, he modeled likely habitats in North America.

He analyzed the climatic data from Asia, Australia and New Zealand, where the tick is established and then compared to the North American climate reports.

The most suitable habitat for the tick included the coastal areas north of New Brunswick and Nova Scotia, as far south as Virginia and North Carolina, Rochlin discovered. On the west coast, the coastal area where the tick will likely survive ranged from southern British Columbia to northern California.

Diseases that have been transmitted by ticks and mosquitoes more than triple since 2004 in the USA.

Large areas of the interior can also become the home of this ticking: from northern Louisiana to Wisconsin and south to Ontario and Quebec as well as to west Kentucky, Tennessee and Missouri, showed his study.

Asian longhorned ticks can become "very abundant" in favorable habitats, Rochlin said. "Along with the aggressive biting behavior of this species and its potential to carry human and animal pathogens, this species represents a significant public health concern."

Placing Asian longhorned tick in perspective

Erika Machtinger, an assistant professor of entomology at Pennsylvania State University's College of Agriculture, said what is "wonderful" in the new study is that it gives "information that everyone is wondering: where could it go, or where could it be?"

Machinger, who was not involved in the new research, said she likes to "put these scary things in perspective." The Zika virus was one of them.

"When you think about the native pathogens we have here that are a problem, the Zika virus was a speck on the radar," Machtinger said of concerns about Zika in the United States in 2016. The native Lyme disease pathogen infects about 320,000 people every year. year and "can cause mortality. It can cause serious debilitating effects," she said. "That's a problem. [tick] is something that we need to be aware of and continue to monitor, but people need not be afraid of it. "
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As there have been few cases of this tick feeding humans, the biggest concern may be cows and other veterinary problems, said Machtinger. Still, it did not totally minimize the threat because this is the first introduction of an invasive tick that the United States has seen in 80 years, she said.

Much like rabbit rick, bird tick and other native species, Asia's long-tailed tick was "forgotten for a few years," said Machtinger, who believes he may be here from 2010 or even earlier. "That's the important piece: it's here, but it's here," she said. "And it will not take over the northeast or the eastern part of the US quickly if it raises the numbers."

Although their ability to clone means that a tick can easily produce a couple of thousand eggs, "so can our native black-legged ticks," Matchinger said. Ultimately, she said, the Asian longhorned tick may not be more scary than some native species.

Rochlin said the infiltration of tick species in the United States "strengthens the need to develop a comprehensive strategy for tick control and prevention of tick-borne diseases." He added that the best defense for those who are worried is to practice "the usual precautions against tick bites recommended by the CDC," such as treating clothing and equipment with products containing 0.5% permethrin and checking his body for ticks after being outdoors.

Machtinger advised: "Be diligent in protecting you and your animals." And if you find a tick you've never seen before, take it to a veterinarian or a university and ask for help.

"We rely on our community scientists," she said. "We trust people out there and find strange things in their animals that they have not seen before to bring it [in] and say: "Where can I get this identified? Can you help me? "

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