Lyme disease is set to explode and we still don’t have a vaccine
A new prediction says 2017 and 2018 will see major Lyme disease outbreaks in
new areas. This could lead to lifelong health consequences, so where's the
vaccine?
Tick tock
Mike Peres/Custom Medical Stock Photo/SPL
By Chelsea Whyte
BY THE time he had finished his walk through the woods in New York state, Rick
Ostfeld was ready to declare a public health emergency. He could read the
warning signs in the acorns that littered the forest floor – seeds of a chain
of events that will culminate in an unprecedented outbreak of Lyme disease this
year.
Since that day in 2015, Ostfeld has been publicising the coming outbreak.
Thanks to a changing climate it could be one of the worst on record: the ticks
that carry the disease have been found in places where it has never before been
a problem – and where most people don’t know how to respond. The danger zone
isn’t confined to the US: similar signs are flagging potential outbreaks in
Europe. Polish researchers predict a major outbreak there in 2018.
In theory, Ostfeld’s early warning system gives public health officials a
two-year window to prepare. In many other cases, this would be enough time to
roll out a vaccination programme. But there is no human vaccine for Lyme
disease. Why not? And what can you do to protect yourself in the meantime?
.
Lyme disease is the most common infection following an insect bite in the US:
the Centers for Disease Control estimates that 300,000 Americans contract Lyme
disease each year, calling it “a major US public health problem”. While it is
easy enough to treat if caught early, we are still getting to grips with
lifelong health problems that can stem from not catching it in time (see “Do I
have Lyme disease?“).
This is less of a problem when Lyme is confined to a few small areas of the US,
but thanks in part to warmer winters, the disease is spreading beyond its usual
territory, extending across the US (see map) and into Europe and forested areas
of Asia. In Europe in particular, confirmed cases have been steadily rising for
30 years – today, the World Health Organization estimates that 65,000 people
get Lyme disease each year in the region. In the UK, 2000 to 3000 cases are
diagnosed each year, up tenfold from 2001, estimates the UK’s National Health
Service.
“Anyone living on the edge of the Lyme disease maps now will likely be at risk
soon”
So how could a floor of acorns two years ago tell Ostfeld, a disease ecologist
at the Cary Institute of Ecosystem Studies in Millbrook, New York, that 2017
would see an outbreak of Lyme disease? It’s all down to what happens next.
A bumper crop of the seeds – “like you were walking on ball bearings” – comes
along every two to five years in Millbrook. Crucially, these nutrient-packed
meals swell the mouse population: “2016 was a real mouse plague of a year,” he
says. And mouse plagues bring tick plagues.
Soon after hatching, young ticks start “questing” – grasping onto grasses or
leaves with their hind legs and waving their forelegs, ready to hitch a ride on
whatever passes by, usually a mouse.
Gut reaction
Once on board, the feast begins. Just one mouse can carry hundreds of immature
ticks in their post-larval nymph stage.
This is where the problems for us start. Mouse blood carries the Lyme-causing
bacterium Borrelia burgdorferi, which passes to a tick’s gut as it feeds. The
tick itself is unharmed, but each time it latches onto a new host to feed, the
bacteria can move from its gut to the blood – including that of any human
passers-by.
“We predict the mice population based on the acorns and we predict infected
nymph ticks with the mice numbers. Each step has a one year lag,” Ostfeld says.
Ostfeld published his discovery of this chain of causation in 2006. Last year,
researchers in Poland found the same trend there, with the same implications.
“Last year we had a lot of oak acorns, so we might expect 2018 will pose a high
risk of Lyme,” says Jakub Szymkowiak at Adam Mickiewicz University in Poznan,
Poland.
Those who live in traditional Lyme disease zones are well versed in tick
awareness – wear long trousers in the woods, check yourself thoroughly
afterwards, and more. But this advice will be less familiar in places that used
to sit outside Lyme zones – like Poland. “That’s sort of the perfect storm,”
says Ostfeld. “The public is unaware, so they’re not looking for it and they
don’t get treated.”
It’s not obvious when you have been bitten or infected: ticks are the size of a
poppy seed, and not everyone gets the classic “bullseye” rash that is supposed
to tip you off. The flu-like symptoms that follow are also easy to misdiagnose.
And because antibodies to Lyme disease take a few weeks to develop, early tests
can miss it. “That’s when you get late-stage, untreated, supremely problematic
Lyme disease,” Ostfeld says.
The best approach would be to vaccinate people at risk – but there is currently
no vaccine. We used to have one, but thanks to anti-vaccination activists, that
is no longer the case.
In the late 1990s, a race was on to make the first Lyme disease vaccine. By
December 1998, the US Food and Drug Administration approved the release of
Lymerix, developed by SmithKline Beecham, now GSK. But the company voluntarily
withdrew the drug after only four years.
This followed a series of lawsuits – including one where recipients claimed
Lymerix caused chronic arthritis. Influenced by now-discredited research
purporting to show a link between the MMR vaccine and autism, activists raised
the question of whether the Lyme disease vaccine could cause arthritis.
Media coverage and the anti-Lyme-vaccination groups gave a voice to those who
believed their pain was due to the vaccine, and public support for the vaccine
declined. “The chronic arthritis was not associated with Lyme,” says Stanley
Plotkin, an adviser to pharmaceutical company Sanofi Pasteur. “When you’re
dealing with adults, all kinds of things happen to them. They get arthritis,
they get strokes, heart attacks. So unless you have a control group, you’re in
la-la land.”
But there was a control group – the rest of the US population. And when the FDA
reviewed the vaccine’s adverse event reports in a retrospective study, they
found only 905 reports for 1.4 million doses. Still, the damage was done, and
the vaccine was benched.
After that, “no one touched it”, says Thomas Lingelbach, CEO at Valneva, a
biotech company based in France. Until now: Valneva has a vaccine in early
human trials. It will improve on Lymerix, acting against all five strains of
the disease instead of just the one most common in the US, and it will be
suitable for children.
Lingelbach knows the battles his firm will face. “It will be hard to convince
anti-vax lobbyists,” he says. That fight is still some way off: any public
roll-out is at least six years away.
What makes this wait especially galling for some is that there is a vaccine for
your pet. “It’s ironic that you can vaccinate your animal and you can’t
vaccinate yourself,” Plotkin says.
In the animal vaccine, instead of exposing Fido to a weakened version of the
antigen to trigger antibodies, it works within the tick, neutralising B.
burgdorferi by altering the expression of a protein on the bacterium before it
enters the bloodstream. This is how a human version would work. “The underlying
scientific principle is not very far away from what it is in the veterinary
environment,” says Lingelbach.
“It’s ironic that you can vaccinate your animal, but you can’t vaccinate
yourself”
Some people have suggested taking the animal vaccine, but Plotkin doesn’t
recommend this as it hasn’t been tested in people so there is insufficient
safety data. “You just don’t have classical efficacy data in humans,” he says.
It is also illegal in the US and UK for vets to practise medicine on humans.
While we wait for a human vaccine, you might start keeping track of your local
acorn populations – but brush up on your anti-tick measures before you hit the
woods.
DO I HAVE LYME DISEASE?
The symptoms of Lyme disease, which you can get from a tick bite, aren’t always
obvious. At the site of the bite, a red splotch will often start to grow into
what looks like a bullseye target.
Not everyone gets this unmistakable sign, however. Over the next few weeks,
flu-like symptoms, including aches and fever, can follow. Left untreated, Lyme
disease can lead to a host of problems, chronic joint inflammation, facial
palsy, issues with short-term memory, heart rhythm irregularities, and
inflammation of the brain and spinal cord.
WHAT TO DO
IF YOU’VE BEEN AROUND TICKS
The best way to prevent Lyme disease is to do a thorough tick check. Nymph
ticks are so tiny they can be hard to spot, so find a partner, strip down, and
go over places that are hard to reach. Make sure you check your partner’s
armpits, scalp and groin for ticks.
IF YOU FIND A TICK
If you know it has been on you for under 36 hours, use tweezers to pull it out
correctly, and you will probably be fine. That’s because the Lyme-causing
bacteria that live in a tick’s gut are slow, and it takes 36 to 48 hours for
them to make it into your bloodstream. Always see a doctor if you are unsure.
IF YOU’VE MISSED THE WINDOW
It’s best to see a doctor for a Lyme disease test – but not right away. Your
antibodies to Lyme disease take weeks to form, so an early test can give a
false reassurance. Wait four to six weeks before requesting a blood test.
IF YOU TEST POSITIVE
If you do test positive for Lyme disease, a course of antibiotics will usually
stop the infection in its tracks fairly quickly.
IF SYMPTOMS LINGER
A small percentage of people who are treated will continue to have symptoms
like fatigue or sore joints and muscles. This condition is called
post-treatment Lyme disease syndrome, sometimes referred to as chronic Lyme
disease. It isn’t exactly clear what causes these symptoms, it could be a
delayed immune response or even another illness altogether. Until this
controversial area of medicine is clarified, it’s best to avoid getting Lyme
disease in the first place, at least while a vaccine is still in development.
