It’s an unfortunate yet undeniable fact — an increasing number of us truly do live in a “more ticks in more places” world. Not a week goes by at TickEncounter without our hearing at least one report from just regular folks about how they’ve lived in their homes for 8, 10, 20 or more years and never experienced ticks until NOW. Or that they’ve recently moved their home from one place to another only to find out that they now live where ticks do. The “more ticks in more places” phenomenon hits home … or at least, close by. It follows that more ticks also means more tick bites; and more tick bites, well … has resulted in an explosion in the incidence of tickborne disease, not just in the northeastern United States, but in an ever-growing swath across North America, along with much of the north temperate zone globally. In America alone, estimates indicate that more than 476,000 new cases of Lyme disease, the leading tickborne illness nationally, are diagnosed every year now [update: as of 2021]. Lyme is just one disease of several caused by germs carried and transmitted by ticks. And that IS a problem! A large, and growing population of sick people (and pets) is rarely ever NOT a problem.
This past year, and every other year going back to 2018, many have been witness to the hard work done1 by a brilliant collection of scientists, health professionals, and citizen advocates, with their broad array of perspectives and experiences convened by the national Health and Human Services director as an advisory working group. Their charge was to review the state of knowledge regarding tickborne disease and to highlight and prioritize important gaps that must be filled in order to provide relief for this serious and costly public health burden. Much, if not most of the focus of this committee has been on finding solutions to the sometimes-complex medical outcome of a tick bite. And that is certainly one important perspective on the problem. But while it seems to frequently get lost in the discussions over testing and treatment, case definitions and the politics of health care, another equally important viewpoint is that Lyme and the other tickborne diseases almost always start with a tick bite. Not just any tick bite, but one delivered by an infected, vector-competent type of tick. This detail is important and an all-too-common knowledge gap for a majority of people living in our “more ticks in more places” world. The different types of the most common ticks in North America really do carry different disease germs. Different ticks are responsible for causing different diseases! Along with carrying different germs, the different types of ticks also lead different lifestyles and rely on different hosts to survive and thrive. And all of that got me thinking about how important one’s perspective can be. The type of tick matters.
“Perched in a tree stand…I watched as the true genesis of the Lyme problem…passed by.“
Perched in a tree stand, 20 feet above the forest floor, I watched as the true genesis of the Lyme problem humbly browsed and sniffed its way among the low brush below. A white-tailed deer, soon followed by another and another passed by. Sitting there and watching from overhead with just a bit of awe and fascination, I mused that most of the people currently infected with Lyme disease, along with those who have recovered from Lyme disease, and those who may someday get Lyme disease, probably would still hold this majestic-looking animal in some kind of higher regard. These animals passing below me, and hundreds of thousands like them across North America, are really where this historic tick story starts. When an adult blacklegged tick (Ixodes scapularis and Ixodes pacificus in the United States) or one of its cousin blacklegged ticks across the globe steals blood from a deer, it then has the protein source it needs to produce thousands of eggs, that hatch to collectively produce trillions of tiny larval stage ticks. Larval ticks, in their turn, steal blood from a wider array of host animals, fishing out various germs along with their blood meal. That blood meal of the larvae allows the tick to grow into a next developmental stage, called the nymph. And those germs picked up by the larvae then pass into the nymph as it completes its metamorphosis. When the nymph is ready to take its own blood meal, it can pass along any of the germs it might have acquired while it was a blood-feeding larva—and most commonly, the Lyme disease spirochete. The perspective of many — maybe most — is it’s those germs that are the problem. So, of course the greatest need and loudest cry would seem to be for better germ detection and germ killing. But in my view, it’s the ticks, and more precisely, certain types of vector-competent ticks, occurring in more places … places where they’ve never been encountered before … that are the overlooked keystone of Lyme disease.
We could have more American dog ticks in more places, or Lone Star ticks, or Gulf Coast ticks, or even invasive Asian longhorned ticks, and still we wouldn’t have more cases of Lyme disease. But more blacklegged ticks in more places … that’s what has led to the explosion in Lyme disease over the past few decades. And it’s probably not much of a reveal to most people, but the one newer and ever-more constant fixture in their local landscapes are these majestic enigmas — deer — readily serving as the main source of reproductive nutrients for blacklegged ticks. From the deep woods, deer have moved to and through suburbia, on into urban parklands. They run down Main Streets in mid-sized towns and camp out in back yards. And the ticks that come with them are laying billions of eggs in places where they’ve never been laid before, producing larvae and nymph ticks that imbibe blood-and-germ cocktails from ubiquitous small rodents and birds.
Well now, isn’t that a fine fix a lack of ecological balance from predators (animal or human) has gotten us into. So, where are the solutions? It may be that further meddling with nature will actually prove more challenging than finding the medical miracle to kill disease-causing germs. But it also seems important to remember it may not be enough to find a medical cure for Lyme disease while leaving alone a thriving tick presence. For certain, ticks are usually not merely benign annoyances. There are likely more strains of germs for these ticks to find, and it’s likely only a matter of time until others of these germs rise to mount yet another public health crisis.
1https://www.hhs.gov/sites/default/files/tbdwg-report-to-congress-2018.pdf
Do you share the same perspective as the TickGuy? Maybe you will once you see what he sees on the back corner of his yard. Click the video to watch.