In October 2016, author and investigative journalist Mary Beth Pfeiffer was visiting New York’s Metropolitan Museum of Modern Art when she found herself standing before one of Claude Monet’s masterpieces: Poppy Fields near Argenteuil. In its classic pastoral scene, a young boy makes his way through a field tinted with orange poppies and green thrush. A woman, perhaps his mother, walks beside him in a beige bonnet and flowing blue gown, dangling a turquoise umbrella over her shoulder. The two, at ease beneath a patchy blue sky, seem to nearly disappear into the tall, wild grasses all around them.  

For Pfeiffer the scene triggers not admiration but anxiety.

“I can no longer look at such pastoral loveliness without seeing what lurks within,” she writes in her new book, Lyme: The First Epidemic of Climate Change (Island Press, April 2018). “I know what’s there.”

Since 2012, Pfeiffer has been investigating the explosive growth of tick populations in the United States and around the world, and with it, the rising incidence of Lyme and other tick-borne diseases. What she has discovered, both about the disease itself and the woefully flawed methods with which it is tested, diagnosed, and treated, is enough to give anyone lacing up their shoes for a leisurely stroll in the outback some serious pause.  

“Blacklegged ticks have taken up residence in half of continental America’s counties, spreading west, north, and south from the Connecticut town from which Lyme disease was named in the late 1970s, like some unchecked algal bloom,” she writes. “These eight-legged arachnids have turned childhood from a time to explore nature to a time to fear it.”

Lyme disease is caused by the Borrelia burgdorferi bacterium and transmitted most commonly through the bite of an infected tick. The disease can be treated through antibiotics and is curable, but only if caught in its early stages. If left undiagnosed, Lyme disease can lead to debilitating symptoms ranging from memory loss and joint pain to muscle fatigue and depression. Over time, it can become resistant to any treatment.

As climate-induced warming has altered the planet ecosystem, tick populations, long known to be carriers for the Lyme bacterium, are expanding the world over, nurtured by earlier and longer springs. While Pfeiffer is clear that we don’t yet know whether climate change is solely responsible for this expansion, evidence abounds that human-induced global warming is helping it along—something the U.S. government codified in its own climate models years ago. 

The CDC first began tracking Lyme in 1996; Pfeiffer examines 18 years of maps since then that reveal the spread of Lyme across the northeast and midwest United States. In 2014, the EPA cited Lyme as one of four indicators to track and measure the impacts of climate change in a report the agency issued. “The tick-borne illness is the only disease to be treated with that distinction,” Pfeiffer writes. 

A warming world isn’t the only possible reason that ticks—and with them, Lyme—are spreading. Pfeiffer presents a sobering analysis of how parks and nature preserves have turned sprawling woodlands into tick sanctuaries, which have in turn become incubators for Lyme disease. These “woodburbs,” as one Yale University researcher calls them, are pleasant green landscapes for residents, but they are also essential to the survival and sustenance of ticks.

The tick is a remarkably efficient arachnid with a unique talent for delivering an equally efficient disease through its bite. Ticks can detect the breath of a potential victim from 50 feet away and are built like tanks, nearly impervious to a pinch, swat, or attempted crushing blow. In the case of the Ixodes ricinus tick, Pfeiffer explains in gruesome detail how it deploys two spear-like appendages to pierce the epidermis of its victim, then extends and retracts them over and over, cutting, sawing, and stabbing away at its meal. The victim doesn’t even feel the bite because the tick’s saliva contains an anesthetic like a novocain to numb the skin. The saliva also contains molecules that prevent the victim’s blood from clotting so that it can continue feasting without interruption. Once the tick is in place it uses its saliva to build a hardened seal around the bite. The arachnid’s remarkable saliva is also a perfect container for a host of potentially devastating diseases, specifically, Lyme.

The Borrelia burgdorferi spirochete that causes Lyme is itself “a bug of many talents,” Pfeiffer writes. When it passes from the tick’s mouth to a human, B. burgdorferi stops producing the protein that helps it stick to the tick’s digestive tract. This allows the bacterium to pass into its host without triggering an immune response. When it enters the bloodstream, “akin to a kayaker on the Colorado River after a raging storm, B. burgdorferi swings on tethers within blood vessels, planting anchors along the way to steady and slow its movement.” It then uses a propulsive flagellum shielded by a membrane to help it “swim Olympian-like through fluids that would be the death of many bacteria and to penetrate tough joint capsules, the peridardium around the heart, and meninges that encase the brain, something few bacteria can do.” 

Every year, upwards of 300,000 people are diagnosed with Lyme. But while other diseases like Zika have garnered mass media attention, Lyme hasn’t. Pfeiffer puts the blame squarely on the medical community, which she says is poorly equipped to handle a Lyme epidemic. She presents heart-wrenching stories of those who have suffered the most from this medical echo chamber, such as Barbara Pronk—an employee of Royal Dutch Shell in the Hague who eventually took her own life, but not before writing a moving letter decrying the lack of support for Lyme victims and the need for a complete culture shift to assist them in dealing with the disease.

While little effort is being made to raise public awareness about the disease, Pfeiffer laments a culture in which physicians often misdiagnose patients, losing valuable time for treatment, while others hesitate to prescribe antibiotics for longer than medical protocols suggest for fear of losing their license, which can discourage testing and diagnosis. She tracks the history of how open-access medical publications have led to a raft of articles dismissing Lyme’s ability to survive antibiotic treatment, and critiques a kind of medical echo chamber, in which about two dozen researcher-physicians have dominated how Lyme gets treated and diagnosed. 

“In the five years of writing about Lyme disease," she writes, "I have found a medical landscape that is breathtakingly controversial and, in many ways, dysfunctional, one characterized less by warring sides than by parallel universes.”