Black-legged, or deer, tick (Ixodes scapularis). Credit: Encyclopædia Britannica, Inc.

Spring has arrived in the northeastern and north-central tier of states, from Maine south to Maryland and west to Minnesota, and with the arrival of that glorious season of rebirth comes a worry: the annual reemergence of the deer (or black-legged) tick, and with it the possibility of tick bites, and with that possibility the further possibility of falling victim to the terrible malady called Lyme disease.

Lyme disease, a spirochete-borne illness that in its worst manifestations attacks the joints, organs, and nervous system of stricken humans, would seem to be a fairly new breed of pestilence, having been identified only in 1975. Since it is difficult to diagnose, Lyme disease may have existed long before then and simply been properly identified recently, but it also may have been one of those perfect-storm catastrophes that required only the proper combination of factors to evolve.

For reasons that are not entirely clear, the Centers for Disease Control and Prevention (CDC) observed a steady rise in the incidence of Lyme disease since 1990: in recent years, some 22,000 to 30,000 cases are confirmed each year, with a rough average of about 25,000. One possible factor is the warming climate, which makes conditions congenial for ticks—and their deer hosts, and humans and their pets as well—for longer periods of the year, but it is also possible that the increase may simply have to do with better reporting by health agencies.

When I was a kid playing in the Virginia woods, I had the benefit of a keen-eyed grandmother who had a fierce passion for finding and destroying ticks before they dug in. The easiest way to avoid Lyme disease is to stay out of the woods, which deprives us of a primordial pleasure. The second easiest is to remember something of our deep primate past and engage in that grandmotherly grooming, which would keep ticks from making a meal of a person. The problem is, the deer tick is tiny, tiny, tiny. But so, too, is the incidence of the disease; it’s worth noting that the risk of contracting the malady is small—only some 2–3 percent of people who are bitten by ticks develop Lyme disease. And, according to a recent study reported in the flagship journal of the American Society for Microbiology, not every strain of the carrier bacterium is dangerous, which improves the odds even more in our favor.

But that said, Lyme disease and its various kin (southern tick disease, Lone Star virus, and so on) are nothing to brush away: they can be debilitating at best, fatal at worst, and the disease is estimated to cost billions of dollars to lost productivity and other factors. There are no vaccines currently on the market, and antibiotics are not always effective and can have undesirable side effects in some people, though improved diagnostic methods are reportedly in the works. And another ASM report has identified the invasive pathway used by the bacterium that causes granulocytic anaplasmosis, the second most prevalent tickborne disease after Lyme, which opens the door to combatting tickborne illnesses of all kinds.

For more information, the University of Nebraska entomology department offers a useful visual guide to identifying different kinds of ticks. The CDC also maintains a webpage that is well stocked with information, while the American Lyme Disease Foundation is a good source of developing news.