H5N1

Why is Lyme disease so hard to understand?

In The Atlantic, an important article by Meghan O'Rourke, a Lyme patient: Why Is Lyme Disease So Hard to Understand? Excerpt:

Even as changes in the climate and in land use are causing a dramatic rise in Lyme and other tick-borne diseases, the American medical establishment remains entrenched in a struggle over who can be said to have Lyme disease and whether it can become chronic—and if so, why. The standoff has impeded research that could help break the logjam and clarify how a wily bacterium, and the co-infections that can come with it, can affect human bodies. 

After 40 years in the public-health spotlight, Lyme disease still can’t be prevented by a vaccine; eludes reliable testing; and continues to pit patients against doctors, and researchers against one another. When I got my inconclusive diagnosis, I knew better than to dream of a quick cure. But I didn’t know how extreme the roller coaster of uncertainty would be. 

Lyme disease came into public view when an epidemic of what appeared to be rheumatoid arthritis began afflicting children in Lyme, Connecticut. A young rheumatologist at Yale named Allen Steere, who now conducts research at Massachusetts General Hospital, in Boston, studied the children. In 1976 he named the mysterious illness after its locale and described its main symptoms more fully: a bull’s-eye rash; fevers and aches; Bell’s palsy, or partial paralysis of the face, and other neurological issues; and rheumatological manifestations such as swelling of the knees. After much study, Steere realized that the black-legged ticks that live on mice and deer (among other mammals) might be harboring a pathogen responsible for the outbreak. 

In 1981, the medical entomologist Willy Burgdorfer finally identified the bacterium that causes Lyme, and it was named after him: Borrelia burgdorferi. 

B. burgdorferi is a corkscrew-shaped bacterium known as a spirochete that can burrow deep into its host’s tissue, causing damage as it goes and, in laboratory conditions at least, morphing as needed from corkscrew to cystlike blob to, potentially, slimy “biofilm” forms. Because of this ability, researchers describe it as an “immune evader.” Once it hits the human bloodstream, it changes its outer surface to elude an immune response, and then quickly moves from the blood into tissue, which poses problems for early detection. (Hard to find in the bloodstream and other body fluids, the B. burgdorferi spirochete is hard to culture, which is how bacterial infections are definitively diagnosed.) 

If it goes untreated, B. burgdorferi can make its way into fluid in the joints, into the spinal cord, and even into the brain and the heart, where it can cause the sometimes deadly Lyme carditis.

UK: Lyme disease cases may be three times higher than estimated

Via The Guardian: UK Lyme disease cases may be three times higher than estimated. Excerpt:

Cases of Lyme disease in the UK may be three times higher than previous estimates, according to new research. 

After analysing the anonymous medical records of 8.4 million people from across the UK, scientists forecast that the total number of Lyme disease diagnoses in the UK could top 8,000 in 2019, compared with previous estimates of between 2,000 and 3,000 annual diagnoses. 

Lyme disease is a bacterial infection, which is passed on through being bitten by an infected tick. The small spider-like creatures feed off the blood of animals and are typically found in dense, moist vegetation.

Lyme disease has many symptoms, making it difficult to diagnose. Early symptoms can be similar to those of flu, and about a quarter of cases will develop a circular red rash around the bite. Full clinical diagnosis requires a blood test, but the study found that more than half of patients in 2012, the most recent year with complete data, were treated with only “suspected” or “possible” Lyme disease.  

If caught early, most cases can be successfully treated with antibiotics within four weeks, but the infection can lead to permanent damage to the joints and nervous system.

The research, published in the journal BMJ Open, found that half of cases occurred between June and August. Although there were diagnoses across all regions of the UK during the period studied, Scotland had the highest number of cases, at 27% of the total. The authors suggest this could be due to the region’s wetter climate and popularity with hikers. The south-west and south of England also recorded a higher than average number of cases. 

The data showed that the number of diagnoses increased almost tenfold over the period studied. This, the researchers said, was partly down to increased caution by GPs and greater public awareness. 

“The exact number isn’t so important,” said Dr Victoria Cairns, the lead author of the study. “The point is that it’s a lot, and it’s everywhere, and that’s why people should be informed.”  

Dr Anne Cruikshank, the Royal College of GPs’ clinical champion for Lyme disease, said: “These levels are not a big surprise to those of us who know about Lyme disease. I expect the 8,000 figure may be an underestimate, since the data shows that positive lab results have doubled every five years.”

Lyme disease: Is a solution on the way?

Via The Guardian: Lyme disease: is a solution on the way? Excerpt:

As a former martial arts world champion, who trained daily and enjoyed camping and hiking at weekends, Stephen Bullough had always prided himself on leading a healthy life.  

Like most people, he thought very little when he was bitten by a tick on a camping holiday close to home in Wigan in 2014, never suspecting that this tiny bite would unleash an infection in his body that would one day leave him permanently incapacitated.  

“He had a rash on his right arm, which we put down to ringworm, so we put a bit of cream on it and thought nothing of it,” remembers Angela, Stephen’s wife. “In 2015, he started to develop these cognitive problems, getting words wrong. We laughed about it at first, joking, ‘You’re getting old now.’”  

But a year later, Bullough began to experience sudden seizures and muscle weakness, leaving him with severe difficulties walking. Over the past three years, his condition has rapidly deteriorated, leaving him unable to see, permanently bed-bound and often suffering multiple seizures at a time.  

“Last May, he had a massive seizure and then his whole body was convulsing,” says Angela. “That’s the day he went blind and has never walked or seen since. He then started having back-to-back seizures; he’s in hospital once a month because they just won’t stop, regardless of how many drugs they give him. One weekend, he had 40 seizures.” 

Bullough was eventually diagnosed with Lyme disease, an illness caused by various species of bacteria in the genus Borrelia that live in the guts of ticks. Once transmitted to humans, it can attack the immune system and lead to serious health complications such as arthritis, meningitis, neurological problems, even heart failure. While Lyme disease can sometimes be treated with antibiotics if detected early, not everyone responds and for patients such as Bullough who have developed chronic symptoms, there is currently no cure.

This is particularly concerning as Lyme disease appears to be on the rise, something scientists have attributed to climate change, creating conditions in which tick populations can thrive. While the disease is currently estimated to affect between 2,000 and 3,000 new people every year in the UK, the National Institute for Health and Care Excellence (Nice) suspects the real figure is far higher. 

But for scientists, one of the most tragic aspects of Bullough’s story, as with those of many other patients, is that it could potentially have been avoided. In the late 1990s, the first preventive human vaccine, called LYMErix, was developed and 1.4m doses had been administered by the end of 2001. The data suggests it was highly effective, protecting against the disease in almost 90% of cases. 

LYMErix wasn’t perfect. It was relatively expensive, did not work in young children, only protected against one strain of Lyme disease and was only available in the US. But it appeared to be the first step towards eradicating the disease for good. Anti-vaccine fear saw it vanish from the market, however, and with that, all scientific research and investment in the field ceased.

The death knell for LYMErix proved to be a theory that the vaccine could induce autoimmune reactions in humans. This was partially based on a study from 2000 that found the vaccine contributed to arthritis in hamsters, as well as entirely hypothetical concerns from the US Food and Drug Administration (FDA) panel, which approved LYMErix, that the immune system might overreact and begin to attack healthy tissue along with the Borrelia bacteria. 

These ideas were subsequently disproved, but the fear continued to spread. In 1998, the now retracted Lancet study linking the MMR vaccine to autism had been published and the modern anti-vaccine movement was gathering momentum. 

Class action lawsuits were filed against LYMErix’s manufacturer after several incidents of arthritis were reported. But while the evidence suggested that these incidents were unconnected to the vaccine, sales began to plummet and in 2002, the product was withdrawn altogether. 

“The consequences have been that, until recently, no manufacturer has wanted to touch this,” says Gregory Poland, who is head of the Mayo Clinic’s Vaccine Research Group in Minnesota. “Some of the anti-vax campaigners had published a statement saying that no matter what kind of Lyme vaccine they develop, we will organise mass protests and lawsuits. In the US, it takes about 10 to 15 years of research and about a billion dollars to develop a vaccine and get it licensed. Since LYMErix, nobody’s been willing to risk that.”

Lyme-infected ticks are so common in parts of Canada, testing no longer done

Via The Globe and Mail: Lyme-infected ticks are so common in parts of Canada, testing no longer done. Excerpt and then a comment:

Lyme disease has settled so deeply into parts of Canada many public health units now just assume if you get bitten by a tick, you should be treated for Lyme disease.  

In Ottawa, where more than two-thirds of the ticks tested in some neighbourhoods carry the bacteria that causes Lyme disease, the public-health unit no longer bothers to test ticks at all. 

Dr. Vera Etches, the unit’s top doctor, said that in 2016 and 2017 more than one-fifth of black-legged ticks tested in Ottawa came back positive for Lyme. 

“That’s a threshold,” she said. “Once you know that more than 20 per cent of the ticks in your area carry Lyme disease bacteria then we don’t need to check in on that. That is what we now call an ’at-risk area.’ ”

That means if a tick is found on a person, and is believed to have been there for more than 24 hours, then the patient should get antibiotics to prevent Lyme infection, even without any testing of the tick. It takes 24 hours before bacteria in the tick’s gut move to its salivary glands and are transferred to a person. 

After three days, the preventive treatment won’t work so patients then wait for symptoms or enough time for antibodies to evolve to show up on a test. It can take more than a month before symptoms appear. They’re mostly similar to the effects of influenza, including fever and aches, as well as – usually but not always – a rash. It typically takes just about as long for the immune system’s antibodies to show up on a lab test.  

If left untreated, Lyme disease can cause serious illnesses such as meningitis, but Etches is quick to point out that because it is caused by a bacteria, it’s treatable with drugs.  

“It’s a good-news story, actually, that there is antibiotics that work to treat Lyme disease,” she said.  

Most public-health offices in Canada used to test ticks submitted by the public, as well as conducting their own surveillance by actively seeking out tick populations and testing them. Some, including Ottawa’s, have decided now that Lyme is endemic, they should shift to public education and prevention as well as treatment. 

Lyme disease was named after the town of Lyme, Conn., where the first case was diagnosed in 1975. It is caused by bacteria that are traded back and forth among black-legged ticks and migratory birds and small mammals like mice and chipmunks. Ticks bite birds and small mammals infected with the bacteria and get infected and then spread the disease when they bite their next victims.

Before 10 years ago, most of the cases diagnosed in Canada were in people bitten by ticks while travelling in the United States. But climate change has led to southern Canada seeing milder winters, which means the ticks that migrate to Canada on the backs of migratory birds are now surviving the winter in larger numbers, spreading the Lyme-causing bacteria more rapidly.  

Canada started keeping track of Lyme disease cases in 2009, when 144 cases were confirmed or considered probable. Only 79 of those cases were believed to have been contracted in Canada.  

In 2017, more than 1,400 cases were confirmed or probable across the country, more than two-thirds of them in Ontario and most of them believed to have been contracted locally. 

National statistics for 2018 are not yet available but in Ontario, the number actually fell significantly, from 967 in 2017 to 612 in 2018. Etches said that was because 2018 was hotter and drier than 2017, and ticks thrive in wet, cool weather.

Cool, wet weather is common here on the BC coast, and we have a lot of ticks. Lyme doesn't seem to have reached us yet, but it will eventually.

I'm more concerned about my dog than about myself; we're in the woods every day, but I don't go crashing through the underbrush the way she does.

So here is my sole, unsolicited and unpaid-for product endorsement: A couple of years ago my wife gave me a TickKey. Two days later I found a tick on our dog, and the TickKey removed it quickly and with no mess. We've been lucky since then, but when the next one turns up (and it will), I'll know what to do—whether the tick is on her or on me. If you live in tick country, you should have this gadget on your key ring.

Lancet study says global warming threatens public health

In The Atlantic, Vann R. Newkirk II writes: Lancet Study Says Global Warming Threatens Public Health. Excerpt:

Climate change can seem almost too big to fathom. Reports like the recent National Climate Assessment or the United Nations’ Intergovernmental Panel on Climate Change recent release have made waves by portraying the dire threats of a warming world, making the case that the fundamental fabric of humanity will be degraded without immediate action. 

But the scenarios—the biblical floods and droughts, the mass migrations of dispossessed people, the creeping seas and the retreating glaciers—have a way of short-circuiting the brain. It’s almost easier to despair or to will oneself into ignorance than to begin to grapple with the future. What are human lives when measured against the coming tempest?   

Efforts to assess the exact human costs of climate change, however, have provided new tools for understanding the ways in which those lives will be impacted. A major report published November 28 in the public-health journal The Lancet provides predictions of how climate change is degrading human health, and how it will alter health-care systems in the future. The findings are reliably grim. But in focusing on the health-care implications and the potential damage done to people and their descendants, the report provides a firm backing to the call to climate action. The experts behind the report hope to marry the urgency of climate science with the muscle of America’s most successful and most trusted policy experiment—its public-health system.

The report, sponsored by 27 academic institutions, a collection of intergovernmental agencies, and the United Nations, features an American Public Health Association-sponsored supplement dedicated to the specific effects of climate change on America. Authors Renee Salas, Paige Knappenberger, and Jeremy Hess examine what they propose are the three main ways in which a warming world will affect the health of Americans. 

For one, the heat itself and the increased intensity and duration of heat waves will make people sick, along with exacerbating existing conditions and reducing the productivity of workers. 

Second, as has been demonstrated in recent disasters, the rising severity and frequency of extreme weather events will elevate threats to health, as well as threats to health systems. 

Last, warmer seasons and warmer water means that the range for illnesses carried by ticks and mosquitoes will spread, putting more Americans in the crosshairs of diseases such as Vibrio, Lyme disease, and West Nile.  

The actual “warming” of global warming is an issue that is often curiously overlooked in terms of its direct effects on human lives. But, as The Lancet’s report shows, it’s the most predictable component of a changing climate, and also the one with measurable effects already. The report points to evidence already indicating links between hotter temperatures and mental-health and cognitive issues. It also points to increased kidney diseases, increases in preterm births, heat exhaustion, increased respiratory diseases, and the advance of antibiotic-resistant bacteria. 

One estimate cited in the report finds that over 3,000 additional people across the country will die prematurely because of higher temperatures by 2050.  

Released just days after the catastrophic fires that burned Paradise, California were contained, The Lancet’s paper also studies the effects of extreme weather events on health. “Since 1980, there has been a steady rise in billion-dollar weather and climate disaster in the U.S.,” the authors write, citing data from the National Oceanic and Atmospheric Administration (NOAA). 

But that finding doesn’t quite capture how much more common extreme events have become, or how much their magnitude has increased in a short time. In 1984 there were two weather events that exceeded $1 billion of damage in today’s dollars, with a five-year average of about $40 billion a year in costs from extreme events. 

In 2017, there were 16 such events, with a five-year average north of $200 billion in annual costs. With each of those comes both direct risks to human lives and the indirect risks associated with the collapse of health-care services and the spread of infectious diseases—consequences that were already highlighted in the deaths of thousands of people in the aftermath of Hurricane Maria in Puerto Rico in 2017. 

 “Perhaps one of the most startling facts is that we truly have climate refugees within the United States,” said Salas in a conference call before the brief’s release. “I think that this is something that a lot of individuals within the U.S. think is a distant effect, but it’s truly something that we’re seeing here today. In fact, earlier this year, I had a patient who came from Puerto Rico. She was elderly, she showed up with her luggage, and truly had a bag with medications that she hadn’t taken in a few weeks … she was truly a climate refugee.” 

And, as Salas notes, the most vulnerable populations to a whole range of health problems are those who’ve been recently displaced. As has emerged recently in studies of disaster-affected communities, they also suffer post-traumatic stress and a uniquely high mental-health burden that can persist for year.

Lyme disease is spreading fast. Why isn’t there a vaccine?

Via The New York Times: Lyme Disease Is Spreading Fast. Why Isn’t There a Vaccine? Excerpt:

We’ve all heard the advice about avoiding Lyme disease. If you walk through wooded or grassy areas where it’s prevalent, you should use insect repellent. Cover exposed skin. Check yourself thoroughly once you return home, and take a shower. If you see a tick, pluck it off your skin with tweezers. Look out for a bull’s eye-shaped rash and flulike symptoms in the summer. A

bout 30,000 cases of Lyme disease are reported to the Centers for Disease Control and Prevention each year, making it the most commonly reported vector-borne illness in the United States. That number has tripled over the last 20 years. And experts estimate that the actual number of cases — not just those that happen to be reported to the agency — is more like 300,000 per year. 

If Lyme has become so common, why isn’t there a vaccine for it? Well, here’s something you may not know: There used to be one, but it was taken off the market more than 15 years ago. And there’s only one new vaccine candidate in the pipeline.  

“Clearly, the problem is getting worse,” said Dr. Paul Mead, a top scientist at the C.D.C. “For years, we have been advocating that people use repellents, do tick checks, spray their yards. That remains good to do, but it’s not enough.”

Tickborne diseases: Confronting a growing threat

Via NEJM: Tickborne Diseases — Confronting a Growing Threat. Excerpt:

Every spring, public health officials prepare for an upsurge in vectorborne diseases. As mosquito-borne illnesses have notoriously surged in the Americas, the U.S. incidence of tickborne infections has risen insidiously, triggering heightened attention from clinicians and researchers.

According to the Centers for Disease Control and Prevention (CDC), the number of reported cases of tickborne disease has more than doubled over the past 13 years. Bacteria cause most tickborne diseases in the United States, and Lyme disease accounts for 82% of reported cases, although other bacteria (including Ehrlichia chaffeensis, Anaplasma phagocytophilum, and Rickettsia rickettsii) and parasites (such as Babesia microti) also cause substantial morbidity and mortality. 

In 1982, Willy Burgdorfer, a microbiologist at the Rocky Mountain Laboratories of the National Institute of Allergy and Infectious Diseases, identified the causative organism of Lyme disease, a spirochete eponymously named Borrelia burgdorferi. B. burgdorferi (which causes disease in North America and Europe) and B. afzelii and B. garinii (found in Europe and Asia) are the most common agents of Lyme disease. The recently identified B. mayonii has been described as a cause of Lyme disease in the upper midwestern United States. 

Spirochetes that cause Lyme disease are carried by hard-bodied ticks (see graphic), notably Ixodes scapularis in the northeastern United States, I. pacificus in western states, I. ricinus in Europe, and I. persulcatus in eastern Europe and Asia. B. miyamotoi, a borrelia spirochete found in Europe, North America, and Asia, more closely related to the agents of tickborne relapsing fever, is also transmitted by I. scapularis and should be considered in the differential diagnosis of febrile illness occurring after a tick bite.

Klain: Are we ready for an epidemic this summer?

Via The Washington Post, an op-ed by Ronald Klain: Are we ready for an epidemic this summer? Excerpt:

Ronald A. Klain, a Post contributing columnist, was White House Ebola response coordinator from 2014 to 2015 and a senior adviser to Hillary Clinton’s 2016 campaign.  

Summer is coming. And if you think a warm-weather surge of mosquitoes and ticks is not as frightening as the fictional winter’s White Walkers from “Game of Thrones,” you haven’t read this week’s report by the Centers for Disease Control and Prevention on the rapidly escalating danger of infectious diseases spread by insects. 

The CDC’s key findings: The number of Americans infected with such diseases, including Zika, West Nile and Lyme, has more than tripled in a decade, jumping from about 30,000 cases a year in 2006 to almost 100,000 in 2016. This total includes nine types of infections never before seen in the United States, including Zika and chikungunya. Looking ahead, 80 percent of state and local health departments are not ready for the insect-borne threat we are facing in just a few weeks. 

Why the surge? Global travel is a major cause; as commerce, culture and tourism spread rapidly, so do diseases. Scientists also identify more infections, thanks to new research tools. But there’s another factor slipped into the CDC report: Certain mosquitoes and ticks are “moving into new areas.” This anodyne language refers to the fact that, as temperatures and moisture rise across the United States, disease-bearing insects expand their reach. Thus, we face another risk posed by the threat that Trump administration officials dare not speak aloud: climate change. 

Coincidentally, the day before the CDC’s report, a man who has worked mightily to save millions from disease threats — Bill Gates — went public with a recent conversation he had with President Trump. Gates told Stat News that they had discussed Gates’s work to try to find a universal flu vaccine; his foundation has offered a $12 million prize for development of a vaccine in hopes of taming a pandemic flu threat that could take more than 30 million lives in a single year. 

As generous as Gates is, however, no single individual has the resources to protect us from the growing array of infectious diseases confronting us: Only government action has that scope.  

And although Gates said Trump was enthusiastic about the universal flu vaccine project, there are reasons to be skeptical that this president’s administration is up to the broader challenge. As Gates reminded the president, nearly a year and a half into his tenure, Trump still does not have a science adviser. John Bolton’s purge at the National Security Council pushed out the official there overseeing pandemic preparation, Tom Bossert. Trump’s controversial CDC director, Robert Redfield, has been busy explaining why he will, or won’t, get paid double what his predecessors made. 

But the biggest challenge is Trump himself. When the United States faced the West African Ebola epidemic in 2014, Trump attacked science-based responses to the threat and essentially argued that President Barack Obama should leave American health-care workers in Africa to die when they were sickened while fighting the disease. (Obama didn’t, and they were saved.) Trump has “energized” the anti-vaccine movement that imperils all that Gates and his allies are trying to achieve. He has proposed an 80 percent reduction in programs designed to stop dangerous diseases overseas before they come to the United States.  

The xenophobia that Trump preached during the 2016 campaign contributed to congressional delay as reports emerged about a Zika outbreak arriving here. Trump’s anti-immigration followers said that tougher immigration laws — not public-health measures — were the way to stop Zika. While Congress dithered, Zika took root in parts of Florida and Texas, and — for the first time in history — the CDC had to issue an advisory against travel to parts of the continental United States.

Tick and mosquito infections spreading rapidly, CDC finds

Via The New York Times: Tick and Mosquito Infections Spreading Rapidly, C.D.C. Finds. Excerpt:

The number of people who get diseases transmitted by mosquito, tick and flea bites has more than tripled in the United States in recent years, federal health officials reported on Tuesday. Since 2004, at least nine such diseases have been newly discovered or introduced into the United States.  

Warmer weather is an important cause of the surge in cases reported to the Centers for Disease Control and Prevention, according to the lead author of a study in the agency’s Morbidity and Mortality Weekly Report. 

But the author, Dr. Lyle R. Petersen, the agency’s director of vector-borne diseases, repeatedly declined to connect the increase to the politically fraught issue of climate change, and the report does not mention either climate change or global warming.  

Many other factors are at work, he emphasized, while noting that “the numbers on some of these diseases have gone to astronomical levels.”  

C.D.C. officials called for more support for state and local health departments. Local agencies “are our first line of defense,” said Dr. Robert Redfield, the C.D.C.’s new director. “We must enhance our investment in their ability to fight these diseases.” 

Although state and local health departments get brief infusions of cash during scares like the 2016 Zika epidemic, they are chronically underfunded. A recent survey of mosquito control agencies found that 84 percent needed help with basics like surveillance and pesticide-resistance testing, Dr. Petersen said.  

The C.D.C. did not suggest that Americans drop plans for playing outdoors or lying in hammocks this summer, but Dr. Redfield emphasized that everyone — especially children — needed to protect themselves against tick and mosquito bites.  

Between 2004 and 2016, about 643,000 cases of 16 insect-borne illnesses were reported to the C.D.C. — 27,000 a year in 2004, rising to 96,000 by 2016. (The year 2004 was chosen as a baseline because the agency began requiring more detailed reporting then.) 

The real case numbers were undoubtedly far larger, Dr. Petersen said. For example, the C.D.C. estimates that about 300,000 Americans get Lyme disease each year, but only about 35,000 diagnoses are reported.  

The study did not delve into the reasons for the increase, but Dr. Petersen said it was probably caused by many factors, including two related to weather: Ticks thriving in regions previously too cold for them, and hot spells triggering outbreaks of mosquito-borne diseases.  

Other factors, he said, include expanded human travel, suburban reforestation and a dearth of new vaccines to stop outbreaks.

Forget Ebola, SARS and Zika: Ticks are the next global health threat

Via The Guardian: Forget Ebola, Sars and Zika: ticks are the next global health threat. Excerpt:

Since the beginning of our species we have been at war. It’s a continuous, neverending fight against the smallest of adversaries: armies of pathogens and parasites. As we have developed new ways to survive and stop them, they have evolved ever more complex and ingenious methods to thwart our efforts.

Humans have faced numerous attempts to challenge our dominance on planet Earth , and from the Black Death to the Spanish flu, we have weathered them all. However, since the start of the 21st century, with its trend towards global interconnectedness, these onslaughts are ever-increasing. In the past 17 years we have battled Sars, the Ebola virus, Mers, and more recently the mysterious mosquito-borne Zika virus. These diseases seem to appear from nowhere and rapidly ravage our populations. One commonality is that they almost always originate in animals before jumping across to people, and few parasites are as good at jumping between animals and people as the tick.  

Ticks could be best described as the used syringes of the natural world due to their promiscuous feeding habits. Most ticks go through three stages in their lives and feed on a different host at each stage, whilst simultaneously collecting hitchhiking microbes in their blood meals. Ticks also have one of the widest distributions of any vector on Earth – they can be found on every continent, including frigid Antarctica. This combination of ubiquity and a bad habit for accumulating pathogenic microbes make ticks some of the most dangerous vectors on the planet.  

So why ticks? And why now? 

Partly, it’s because ticks have been understudied for so long that only recently have we begun to realise just how much they affect our health. It took until 1975 for the infamous Lyme disease even to be formally described, and today the list of microbes found within ticks grows ever larger every year as numerous new species are discovered. 

Changing ecosystems are also forcing ticks into closer contact with humans. Perhaps the most immediate changes are being driven by land clearing, which is forcing wildlife into closer contact with humans; with wildlife come ticks and the diseases they carry. 

Climate change has also been implicated: as the climate gets warmer, some ticks are expanding their ranges into places where cool winter temperatures previously limited their distribution. Geographical boundaries are also being eroded as rapid transport links environments which were previously isolated from one another. This presents easy opportunity for ticks to cross borders and spread to new habitats they may not have previously occupied. 

In short, our manipulation of the environment has set the stage for a tick-driven health crisis.

See also this recent report in Eurosurveillance on tick-borne encephalitis in Sweden.