There’s a New Tick in Town That Scientists Believe Might be a Health Threat
Think you know your ticks? How about Haemaphysalis longicornis—a native of Asia now living in the U.S? Discover now a tick whose bite could ruin your summer.
In an earlier article this Spring we discussed how that about 30,000 cases of Lyme disease are reported to the U.S. Centers for Disease Control and Prevention each year. However, the CDC believes that the real number of cases in the U.S. might be ten times that—as high as up to 300,000 cases yearly.
While you may be familiar with the three most common ticks found to transmit disease in the U.S. such as the Blacklegged Tick Ixodes scapularis; the Lone Star Tick Amblyomma americanum; and the American Dog Tick Dermacentor variabilis, there are actually several other infectious species as well that can transmit a wide range of diseases other than Lyme disease, such as:
• Human ehrlichiosis
• Powassan virus disease
• Tick-borne relapsing fever [TBRF]
In fact, a new study published in the Journal of Medical Entomology reports that a relatively new comer to the U.S. that is commonly referred to as the “Asian Longhorned Tick” has the potential to transmit Rickettsia rickettsii—the tick-borne pathogen known for causing Rocky Mountain spotted fever, a rapidly progressive and potentially fatal disease.
Furthermore, the Asian Longhorned tick has a wide range of hosts that includes dogs, cats, cattle, horses, goats, sheep, white-tailed deer, opossums, coyotes, gray foxes, groundhogs, and raccoons. Therefore, it has the potential to easily wind up in your backyard when you consider how some domestic pets—such as cats—are allowed to roam free; or, when a neighbor thinks it’s a good idea to leave food outside their doorway to feed “the cute raccoons.”
Thus far, the Asian Longhorned tick been found in Arkansas, Connecticut, Delaware, Kentucky, Maryland, North Carolina, New Jersey, New York, Pennsylvania, Tennessee, Virginia, and West Virginia. And while there have not been any cases reported directly linking an Asian Longhorned tick bite in the U.S. with disease, the Longhorned tick is well-established for its ability to carry various disease-causing organisms.
One interesting finding concerning the tick is that it does not appear to find human hosts particularly inviting to bite as shown in the video below:
A display of extreme dislike for human hosts video
However, this is not to downplay the potential threat from this tick species, since in 2018 there was a first-ever documented human-bite case in the United States reported in a scientific journal.
What is the Level of Threat?
In an effort to further understand the threat the tick poses, researchers from the U.S. Centers for Disease Control and Prevention, tested the ticks in the lab on guinea pigs. Their goal was to find out whether the Asian Longhorned tick can both acquire and transmit Rickettsia rickettsii (the parasite behind Rocky Mountain spotted fever) under controlled laboratory conditions, throughout its larval and nymph stages.
What the researchers found was that infection persisted throughout every life stage, all of which were able to transmit R. rickettsii to its hosts. In addition, the female is able to pass on the infectious organisms to the young through her eggs which makes this species especially problematic due to that the Asian Longhorned tick female does not need a male to produce young. The young are begat by a unique process called “parthenogenesis.”
The term “parthenogenesis” comes from the Greek words parthenos (meaning virgin) and genesis (meaning creation) and is used to classify a type of asexual reproduction in which a female gamete or egg cell develops into an individual without fertilization. This is found in species that lack sex chromosomes such as some species of wasps, bees, and ants.
The researchers point out that it should be noted that what occurs in the lab does not necessarily equate exactly with what happens in nature. For instance, the lab animals used are known to be for highly susceptibility to rickettsial infections and levels of rickettsemia uncommon among natural reservoir host species. In other words, what worked in the lab with guinea pigs might not occur with other animals in our backyards.
However, they also point out that their findings indicate that the Asian Longhorned tick could potentially cause an increase in the number of cases of H. longicornis may potentially intensify transmission of R. rickettsii related Rocky Mountain spotted fever in the United States. And, that more study is needed to assess the actual health threat.
What you should do if you think you have found an Asian Longhorned tick
The CDC offers the following advice if you think you’ve spotted or been bitten by an Asian Longhorned tick:
• Remove ticks from people and animals as quickly as possible.
• Save the ticks in rubbing alcohol in a jar or a ziplocked bag.
• Contact your health department, your veterinarian or your state agriculture department or local agricultural extension office about ticks on livestock or for tick identification.
Here is an image to aid identification
If you have seen the Asian Longhorned tick in your backyard that is not included in the states mentioned, let us know about it in the comments section below.
Timothy Boyer has a Ph.D. in Molecular and Cellular Biology from the University of Arizona. For 20+ years he has been employed as a freelance health and science writer. Today, with a background in farming and an avid home gardener, Timothy continues writing about science with a focus on the connection between plant biology and gardening for healthy living. For continual updates about plants and health, you can also follow Timothy on Twitter at TimBoyerWrites.
Image source courtesy of Pixabay and from the U.S. Centers for Disease Control and Prevention, Public Health Image Library public domain image.
“The Ability of the Invasive Asian Longhorned Tick Haemaphysalis longicornis (Acari: Ixodidae) to Acquire and Transmit Rickettsia rickettsii (Rickettsiales: Rickettsiaceae), the Agent of Rocky Mountain Spotted Fever, Under Laboratory Conditions” Hannah M Stanley, Shelby L Ford, Alyssa N Snellgrove, Kris Hartzer, Emily B Smith, Inna Krapiunaya, Michael L Levin; Journal of Medical Entomology, tjaa076, https://doi.org/10.1093/jme/tjaa076
Published:27 April 2020.
“What you need to know about Asian longhorned ticks—A new tick in the United States” Centers for Disease Control and Prevention.