Lyme Read online

  When these researchers are lucky, they find data from some other era that proves their hunch that something has changed. In 1956, a scientist named Cvjetanovic´ in the Bosnian region of the then Socialist Federal Republic of Yugoslavia reported that Ixodes ricinus, the castor bean tick, could not survive at altitudes higher than 800 meters above sea level, or about 2,600 feet. But when Jasmin Omeragic of the University of Sarajevo took another look in 2004, collecting 7,085 castor bean ticks in the Dinaric Alps of Bosnia and Herzegovina, he found them living comfortably at 1,190 meters, or 3,900 feet. In 1957 in Sumava, in then-Czechoslovakia, researchers found the ticks could not survive at elevations above 700 meters. By 2001, biologists found them thriving at 1,100 meters. What those early observations pointed to, wrote Joylon Medlock and his colleagues in 2013, is “clear evidence of an altitudinal expansion of I. ricinus.” Put another way, ticks are aggressively moving up. But they are also moving in other ways—and to places more suited than steep slopes to human habitation.

  In the Hudson Valley of New York State, a team from the University of Pennsylvania used Ixodes DNA to draw a family tree of blacklegged ticks, much the same way that people use saliva swabs to search for distant ancestors in their genetic code. Studying ticks collected at four locations from 2004 to 2009, the researchers recreated a 125-mile upriver tick migration, similar to that of the colonial Huguenots and Livingstons three centuries earlier. The tree begins in southernmost Yorktown, where the tests showed the ticks residing, give or take, for the previous fifty-seven years. Then, seventeen years later, these eight-legged pioneers climb the next rung north, to bucolic Pleasant Valley. Eleven years pass, and they settle in Greenville, in the foothills of the Catskill Mountains, and, seventeen years later, emerge in northernmost Guilderland, where Dutch settlers from New Netherland had settled in 1639. While other DNA literally crept in along the way—mate-searching ticks do follow their hearts—by far the most dominant strain at each point along the march was the one from southernmost Yorktown. The DNA, the researchers wrote, “strongly support a progressive south-to-north expansion.” Defying the odds, the ticks had moved to places where it had long been colder and snowier. And they did just fine.

  In Europe, ticks are on a similarly relentless march north. In Sweden, researchers studied the range of the castor bean tick from 1994 to 1996 by dragging cloths in fifty-seven locations and querying residents about bites and sightings. They were able to establish a boundary line at about 60°5'N, above which the ticks could not survive. By 2008, the ticks were found to have moved some 300 miles north, mainly along the Baltic coast, to about 66°N. In Norway, the story was repeated. Twin surveys in 1943 to 1983 found the ticks unable to survive north of 66°N. By 2011, they had traveled 250 miles, to the highest known latitude in Europe, 69°N, Oslo researchers reported, in a record that seems destined to be, if not already, broken.

  Nicholas Ogden is senior scientist in the National Microbiology Laboratory in the Public Health Agency of Canada. He has watched over the last two decades as blacklegged ticks have leaped the US border in a northerly trek, some 600 miles into Canadian territory. In 1990, the only documented location in Canada where the tick was found was in southern Ontario, in a town called Long Point, which is located on a thin strip of land jutting into Lake Erie and much closer to New York State than to Ottawa, Toronto, or Montreal. Less than two decades later, the ticks had established themselves in a dozen more Canadian locations, including in Manitoba, southeastern New Brunswick, and Nova Scotia. In 2008, Ogden and his colleagues mapped the risk of ticks moving north and predicted “possible widespread expansion” into south central Canada. By 2015, another study put the forecast farther: Lyme-toting ticks would move about 150 to 300 miles north by 2050. That puts Canada in much the same position as the United States in the 1980s, and Ogden knows this. The world’s second largest country, which saw homegrown Lyme cases grow twelvefold from 2009 to 2013, is facing a burgeoning epidemic of Lyme disease. “It is becoming a real public health problem,” he told me.

  In 2015, Ogden and his colleagues employed a novel way to track the destination of ticks on migrating birds. Enter the gray-cheeked thrush, a plain, medium-sized bird and determined skulker that hides in the underbrush, making it prone to collect ticks. Ogden’s team captured the thrush—along with seventy-two other tick-infested birds—as it crossed the Canadian border on its northward migration. Researchers then studied the molecular composition of its delicate, metal gray tail feathers. These rectrices, which help steer the bird in flight, bear a certain fingerprint, an isotope signature from the hydrogen in the water where the bird fledged. Knowing that birds usually return to the place of their birth, scientists concluded the thrush was destined for the farthest reaches of the study, which covered northern Ontario to the southern Canadian Arctic. Charles Francis, who monitors bird populations for the Canadian Wildlife Service, helped in the study. “Very likely there have always been ticks being introduced to northern areas because of migrating birds,” he said. Only now, more of the ticks they carry are surviving in more places. By 2017, Canadian researchers reported that large swaths of Ontario had converted, as a paper in the journal Remote Sensing put it, from “unsustainable to sustainable” for Lyme-toting ticks.

  While the snowshoe hares struggle in the rugged Montana wilderness, ticks and their pathogens are thriving in a warming world, colonizing more places and multiplying there, just as they did in the last great, post-Ice Age warming. Thirty years ago, health officials in Canada told people with Lyme disease that they had almost certainly acquired the infection elsewhere, usually in travel to the United States. By the first decade of the twenty-first century, they had started to hedge their bets.

  A Singular “Indicator”

  In 2014, the US Environmental Protection Agency issued a 112-page report on the future of the United States in a warmer world. It began with a conclusion that had been denied, discounted, and politicized in the states for decades, but at last, or perhaps for the moment at least, was accepted as true. “The Earth’s climate is changing. Temperatures are rising, snow and rainfall patterns are shifting, and more extreme climate events—like heavy rainstorms and record high temperatures—are already taking place. Scientists are highly confident that many of these observed changes can be linked to the climbing levels of carbon dioxide and other greenhouse gases in our atmosphere, which are caused by human activities.”

  The report consisted of six sections that attempted to describe and quantify the effects of global climate change—on oceans, on the earth’s glaciers, on forests and lakes, and on people. In the report’s third edition in 2014, the agency included four new “indicators” to track and measure the impact of climate change. These included the number of annual heating- and cooling-degree days (which are showing Americans using more energy to cool rather than heat); incidence of wildfires; the water level and temperature of the Great Lakes; and last, Lyme disease.

  From this point forward, the agency would track the rate of reported Lyme disease cases across the United States as an official outgrowth and barometer of climate change. The tick-borne illness, with perhaps four million American cases since 1990, is the only disease to be accorded that dubious distinction. In discussing direct health impacts of a warmer earth, the agency cites two other trends to watch: heat-related deaths, which were estimated at 80,000 in the last three decades, and ragweed pollen seasons that cause painful allergies for millions. But Lyme disease has a singular distinction. It is an illness spread by ticks, the EPA report states, whose “populations are influenced by many factors, including climate.”

  In states from Maine to Florida and New York to California, across the breadth of southern Canada and in many parts of Europe, once-sweeping woodlands have been reduced and divided, often into idealized forest fragments at the periphery of residential tracts—places where people can be close to, support, and observe wildlife. Multitudes live, work, and play in or near these green spaces in a new epoch tentatively called th
e Anthropocene, the era marked by the hand of humanity. The irony is that these adulterated slices of nature and de facto nature preserves are incubators, in many of these places, of Lyme disease. The smaller the patch, in fact, the higher the proportion of diseased ticks, as documented in a study in Dutchess County, New York, where the per capita rate of Lyme disease is among the world’s highest.

  In these fragments, small mammals, like white-footed mice in North America and garden dormice in Europe, have found havens, thriving in the absence of predators like foxes. In the language of tick-borne disease, the mouse is quaintly called a “host” for ticks and a “reservoir” of Lyme disease, the place where baby ticks, almost too small to be seen, get their first sip of infection. In city parks, suburban tracts, and exurban preserves, people come skin to skin with these ticks. In scores of studies, other environmental factors besides climate change, many controlled by human beings, are pointed to as drivers of this epidemic. The slicing and dicing of forests, and the loss of biodiversity that followed, is surely high on a complex and evolving list.

  While there is no single explanation for the twentieth-century emergence of Lyme disease, there is ample evidence that climate change has played no small part. Consider New Hampshire. At Pinkham Notch, a mountain pass along the Appalachian Trail, snowfall has declined an average of four inches every decade since 1970, and days below freezing have dropped by three per decade since 1960. Lilacs bloom earlier in New Hampshire, and the growing season is two to three weeks longer than in 1970. This ruggedly beautiful Northeast state had the United States’ second highest rate of Lyme disease in 2013, with a 400 percent increase in cases since 2005. Other research suggests why.

  In the Krkonose Mountains in the northern Czech Republic, temperatures increased by 1.4 degrees Celsius in four decades, and I. ricinus ticks survive as high as 1,299 meters above sea level. “They didn’t decide to go climbing,” a scientist there named Michail Kotsyfakis told me. “It’s just that they can survive in these areas.” In the Montérégie region of southern Quebec, extending south from Montreal to the Saint Lawrence River, temperatures have risen since the 1970s by 0.8 degrees Celsius, and white-footed mice have thrived in shorter, warmer winters. “Its range is rapidly shifting poleward,” Canadian researchers wrote in 2013, pointing to “an increasing body of empirical evidence to support the hypothesis that climate warming is a key driver of Lyme disease emergence, acting upon many levels of the transmission cycle of the disease.”

  The questions are these: Did a changing climate cause this epidemic? Or is climate change merely driving this sickness—with the ticks and animals that circulate it—to new places and new peoples? Evidence most certainly supports the latter. The former is trickier. But Lyme disease is distinctive as the first disease to emerge in North America, Europe, and China in the age of climate change, the first to become entrenched, widespread, and consequential to multitudes of people. It is growing, too, in places like Australia, where residents are told, as they were in southern Canada and still are in many parts of America, Canada, and Europe, that they must have some other illness besides Lyme disease or, if not, they contracted the infection somewhere else. “We’re an island. We have island thinking,” said a country GP from the mid-north coast of New South Wales named Trevor Cheney, who routinely diagnoses Lyme disease though doctors are told it doesn’t exist in Australia. “As if migratory birds”—which drop ticks far and wide—“don’t come there,” he told me at a conference in Paris.

  Such poor advice has cost many Lyme patients valuable time to seek treatment. It stems from a failure, by public health and medical experts, to see the past as future. Lyme disease is moving to new places, as it has for nearly half a century. In the decades since the children of Lyme were infected, little progress has been made to control ticks, protect people from bites, test with certainty for the Lyme pathogen, called Borrelia burgdorferi, and especially, adequately treat the infected.

  Ixodes ticks, blacklegged, castor bean, or otherwise, deserve our respect. They come armed not only with Lyme disease but with a growing menu of microbes: bacterial, viral, and parasitic, known and yet unnamed. Ticks can, and sometimes do, deliver two, three, or four diseases in one bite. So resourceful are infected ticks that two feeding side by side on the same animal may pass pathogens one to the other and never infect the host. So clever is the Lyme pathogen that infected ticks are more efficient at finding prey than uninfected ticks. These ticks may not be able to fly or jump or trek more than a couple of human steps. But they have changed many lives, cost billions in medical care, and colored a walk in the woods or a child’s romp in the grass, our very relationship with nature, with angst.

  This is all the more disturbing when we realize, ultimately, that it is we who unleashed them.

  CHAPTER 2: “Invisible Assassin”

  * * *

  She is a young healthy woman in the photo, glossy blond hair curling softly on her shoulders, red lips smiling, blue eyes shining. She looks confident and smart in a black blazer and white blouse, a glimpse of red reference books on a shelf behind her. Barbara Pronk is at her peak here, a time, long ago, when she was happy and looking forward.

  Barbara had a good job as a personal assistant at Royal Dutch Shell in The Hague, an accomplishment in a country where professional work, at a multinational company no less, was not easy to come by. She had good friends, colleagues who knew they could count on her, and a mother who adored her. She was funny, ambitious, and beautiful, too, a slim, graceful young woman who dressed for work in much the way that she did her job. Impeccably.

  Although she grew up and lived in a small Dutch city called Rijswijk, Barbara loved to travel in the worldly way of many in the Netherlands. There, in one of the earth’s most densely populated countries, where existence is defined by a struggle to hold back the sea, children learn English early and are schooled to see themselves as a small part of a big world. It was a world Barbara embraced.

  When she was in her twenties, Barbara spent three months living with friends near Clearwater, Florida, where she had planted a garden, a Dutch passion, and gone to the beach. During a sabbatical from Shell, she had lived in California for several months, honing her English in a college course in Santa Barbara and sealing her love for the states. An only child, she took regular cruises with her mother, Josephine van der Ven, who was also her good friend. They were so close that Barbara at one point had bought her own apartment but quickly sold it to move back with Josephine.

  In 2005, as her career and life were flourishing, Barbara began to get sick. She suffered overwhelming fatigue and all-over body pain. She developed skin problems and starting losing hair. At the time, Barbara assumed it was the stress of a demanding job as secretary to the comptroller in Shell’s oil and gas unit. When she fainted while shopping and needed first-aid, she again wrote it off to overwork. She was too busy, she had too much to achieve, to be ill. The illness had other plans, however.

  Over a period of six years, Barbara and her mother would travel widely and spend thousands of euros in her search for a diagnosis and a cure. Her symptoms, like those of many such patients, were what medicine calls “nonspecific”—not characteristic of a particular disease but associated with a long list of them. She suffered unremitting joint and muscle pain. She was hypersensitive to light, touch, stress, and sound. Once acutely attuned to detail, she could not remember things but was keen enough to know what it suggested: dementia. In her search for help, Barbara went to some thirty doctors and clinics in the Netherlands and other countries.

  Some doctors said she had myalgic encephalomyelitis or chronic fatigue syndrome, labels that more aptly described symptoms rather than disease. Others doctors were less kind, suggesting the problem might be, as Josephine put it, “between her ears,” or, as Barbara told a friend, “attention seeking.” Barbara did not see it that way, and she started doing research of her own. It made her remember something. There was the time in Florida, a few days after working in the garden
. She had seen a radiating red rash on her leg—she had even emailed her mother about it. At the time, Barbara thought of seeking out a doctor, but it would have been difficult in a foreign country. She dismissed the idea, and the rash went away. Years later, sitting at a computer, trolling for diseases with symptoms that matched her own, Barbara thought she had found her diagnosis in the way that many advanced Lyme disease patients do.

  Deceptive Tableau

  The tidy, affluent country that is the Netherlands is as crowded as, though more livable than, countries like Bangladesh, Rwanda, and India. Its 17 million people live toe-to-toe in well-kept villages, planned suburbs, and cities buzzing with bicycles and commerce. The landscape is flat, low, often reclaimed from the sea, and well used—an amalgam of farm fields, polders, canals, grasslands flecked with sheep, and precious fragments of second-growth forest. The Dutch mourn their environmental plight. They spout statistics on crowding, refer longingly to the wide-open spaces of America, and debate the merits of recycling and modern wind turbines.

  So hungry are Holland’s people to commune with the land that railroad edges are lined with small fenced plots on which rows of lettuce, beans, and flowers are nurtured, and tiny sheds are dressed up as mini-dachas in the country. The Dutch pitch tents on sandy seaside hills and in Friesland woods by the score. They bicycle along the Rhine Canal and down brushy rural paths. They use any patch of warmth and sun, in a rainy country, to dine and sip coffee outdoors.