Researchers have split the medically important American dog tick into two species: the existing Dermacentor variabilis in eastern states and the newly described Dermacentor similis west of the Rocky Mountains. An adult male D. similis tick is shown here. (Photo courtesy of Paula Lado, Ph.D.)
By Melissa Mayer
Rocky Mountain spotted fever spreads when Rickettsia rickettsia bacteria pour into a bite wound while an American dog tick takes a blood meal. Unlike some other tick-borne diseases, which require a longer bite to transmit, Rocky Mountain spotted fever infection may take place within the first 30 minutes of the tick bite.
The distribution of the American dog tick (Dermacentor variabilis) in the United States is a wide yet broken one. It’s mostly found throughout the central and eastern parts of the country—with a few western populations all the way on the other side of the Rocky Mountains. But are these widely separated populations really the same species?
In a study published this month in the Journal of Medical Entomology, a team of researchers at Ohio State University used an integrative taxonomy approach—looking at both physical and genetic evidence—to determine that the ticks formerly known as Dermacentor variabilis in the west are a new species, which they’ve named Dermacentor similis.
Wild, Wild West
Paula Lado, Ph.D.
“We were working on other aspects related to Dermacentor evolution and phylogenetics, and our results consistently showed a separation between populations from the western states and all other locations eastern of the Rockies,” says lead author Paula Lado, Ph.D., who is now with the Center for Vector-Borne Infectious Diseases at Colorado State University. “And that had been shown in other studies in the past, so we decided to explore the topic in depth.”
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The study also found that ticks from Wisconsin and Michigan formed a small subcluster in the eastern group, which means there’s probably some variation there.
The difference between these ticks is in the minutia. They both will happily infect you. While taxonomy considers this a “win” it’s just more research that doesn’t help patients at all. A tick is a tick is a tick. All suck your blood and have the potential of transmitting life-altering pathogens into the human and animal body.
And, because the American dog tick transmits the bacteria that cause Rocky Mountain spotted fever as well as other pathogens, describing a new species like D. similis means taking a close look at which diseases these ticks can carry and how well they do it, which is called vector competency.
“Splitting D. variabilis into two species may mean that they could be vectors for different pathogens,” Lado says. “In my opinion, it is crucial to determine the vector competency of the new species, D. similis. That will allow for us to know what pathogens are transmitted by both Dermacentor species.”
A word of warning on those quotes: all of these variables have been proven over time to be short-sighted as ticks can acquire the ability to transmit things they never used to transmit. They have also been found in places they never were before. Doctors looking at entomology maps have been misdiagnosing people for decades as the information is constantly changing, limited, and imperfect. Please see: The Confounding Debate Over Lyme in the South (Speilman’s maps)
Transmission times have been hotly contested for over 40 years. Mainstream medicine and conflict-riddled researchers and public health ‘authorities’ continue to doggedly state the party line that Lyme transmission takes at least 24-48 hours, whereas reality paints a far different picture, showing the potential transmission of Lyme (and other pathogens) can occur within a few hours. It must also be remembered that minimum transmission time has never been determined, and some coinfections like Powassan virus can be transmitted within minutes. There’s also the sticky issue of partially fed ticks being able to transmit much sooner.
There is an absolute dearth of research on the issue of coinfected ticks and coinfected patients. Does coinfection alter transmission times? The coinfection issue remains in the Dark Ages, leaving patients and the doctors who dare to treat them muddling blindly through the process. But, hey now we know some worthless information about the undersides of ticks!
Again, the only box Lyme/MSIDS fits into is “Pandora’s.” Trying to put a lid on this thing is completely futile.
Below is a picture of a tick, without food or water for days, and the thousands of eggs it laid.
Ticks aren’t picky, and can show up in the wildest of places: