Tickborne diseases are increasing in range and in severity
The Center for Disease Control and Prevention has redrawn its maps of Lyme disease, the disease most commonly carried by ticks, to display how rapidly risk of it is rising in the northeastern US: 260 hot-spot counties now, compared to 20 years ago.
Two years ago, the CDC raised its estimate of the number of new Lyme infections that occur each year in the US from 30,000 to 300,00—10 times as much. Also last month, the Entomological Society of America released a “policy statement” on ticks that amounted to an urgent call for action, saying in part: “…Environmental, ecological, sociological, and human demographic factors [have] created a near ‘perfect storm’ leading to more ticks in more places throughout North America.” This is not only about Lyme disease; it is also other diseases carried by ticks—anaplasmosis, babesiosis, erlichiosis and more—that are less well-known and, because of that, often not detected or treated.
A group of researchers working at the Minnesota Department of Health suspected that the number of tickborne diseases recorded in Minnesota was too low. To test the state’s record, the team randomly selected medical charts from hospitals and clinics. The result: There were three times more case of Lyme, anaplasmosis and babesiosis occurring than the state knew about.
Those high rates in Minnesota turn out not to be unusual. In Arizona, one-fourth (11 out of 42) of high school kids attending a summer football camp came down with another tick-related illness, tickborne relapsing fever. Five of the 11 had to be hospitalized. It was the largest outbreak of the disease in Arizona in 30 years.
Until now, a built-in protection against tickborne diseases has been that the tick species that carry particular pathogens have specific geographical ranges. But as climate change affects animal and insect ranges, those guarantees are collapsing. In Maryland, researchers for the first time have found local ticks carrying babesiosis, a parasitic infection (sometimes called “America’s malaria”) that can be passed undetected by blood transfusions and until recently has been confined to the Northeast.
New tickborne diseases are emerging as well—and often, flying under radar. Dr. Bobbi Pritt of the Mayo Clinic described an illness that affected two men seeking care. Thanks to alert lab workers who noticed the men’s test results were a little off, the cause was identified as a never before seen infection related to a tickborne illness carried by mice. The disease is so new that the organism hasn’t yet been given a name (Erlichia muris eauclairensis has been proposed, to mark the location where it was first spotted), but already, Pritt said, 80 patients have been identified in five states. One-third had to be hospitalized. It’s not clear how wide a range the disease might have.
Finally—because descriptions of tick-related diseases seem to focus on fever and headache and not very serious-sounding symptoms—it was troubling to be reminded by Dr. Paul Mead of the CDC how serious Lyme in particular can be. He described the national detective work that swung into action after a young Massachusetts resident passed out while behind the wheel of a car; that led to a discovery that the victim’s undiagnosed Lyme disease had caused sudden cardiac death. Scouring patient reports, Mead said, revealed 45 patients who survived “heart block”—an interruption of the heartbeat—because of Lyme infection, and five others who died when their Lyme disease triggered what looked like a heart attack.
To hear so many reports in such a short period of time just underlines: Tickborne diseases are increasing, in range and in severity. Whatever we’re doing to protect ourselves, it isn’t enough.
