It’s that time of year again: days are growing longer, trees are
blossoming, birds are tweeting, and the ticks are biting. Spring may
bring about heightened moods, but in the U.S. it also marks the more
unpleasant beginning of Lyme disease season. That’s because the nasty
arthropods that transmit the disease are most active from May through August, conveniently when humans begin to frolic in the grass and bask in the long-awaited sunshine.
With around 30,000
cases reported each year to the Centers for Disease Control (CDC), Lyme
disease has become the most common vector-borne disease in the United
States. While that may not sound like a huge number, it’s estimated that
the actual figure could be five-fold higher due to underreporting.
It’s transmitted to humans through bites from blacklegged ticks infected with the spiral-shaped bacterium Borrelia burgdorferi. While the disease is rarely fatal,
if treatment is absent or delayed it can lead to arthritis, neurologic
problems like meningitis or nerve inflammation, and sometimes even heart
problems.
Although most patients will fully recover after a course of
antibiotics, prevention—as with any disease—is always better than a
cure. Such preventive strategies
include reducing exposure to the vector, for example by wearing
protective clothing, or vaccination. And there was actually a decent,
FDA-licensed vaccine available for Lyme disease, but just four years
following its approval for use in the human population it was withdrawn
by its manufacturers.
Why? In part, due to a shitstorm kicked up by the anti-vaccination movement.
Developed in the ‘90s by pharmaceutical company SmithKline Beecham (now GlaxoSmithKline), LYMErix
was the only licensed Lyme disease vaccine on the market. The vaccine
was based on one of the surface proteins expressed by the
disease-causing bacterium, which was used to evoke an immune response in
the individual. Clinical trials involving more than 10,000 individuals
found that LYMErix reduced new infections in adults by close to 80% and
conferred protection to 100% of children. Additionally, no serious
side-effects were observed.
Despite these positive results, the vaccine was withdrawn from the
U.S. market in 2002 due to a combination of factors. Although it was
considered a cost-effective approach for Lyme disease, its high cost
resulted in slow uptake in clinical settings and reluctance of insurance
companies to cough up for it. This, combined with the emergence of a
hypothesis that the vaccine sparked immune responses that resulted in
arthritis, caused the vaccine’s popularity to plummet.
The idea that the vaccine could cause this “autoimmune arthritis” stemmed from a hypothesis, named the molecular mimicry hypothesis,
which suggested that the protein used in the vaccine displayed
similarity to a protein found in the human body, but was still different
enough to be recognized as foreign by the immune system. This would
mean that, alongside attacking the foreign bacterial protein, the immune
system would also start targeting the normal human protein and thus
lead to an autoimmune reaction.
Within just one year of the vaccine reaching the market, reports of adverse effects
began popping up left, right and center, conveniently mostly about
musculoskeletal pain or swelling as would be expected in patients
suffering from arthritis. The media then soon cottoned on
and began running sob stories on personal experiences that
were guaranteed to draw in readers, fuel fear and spark public outcry.
This was enough to spur investigations and safety surveillance, both
of which failed to find any evidence for either the molecular mimicry
hypothesis nor any spikes in arthritis diagnoses. Yet with an increasing
number of lawsuits filed against the manufacturers and its decreasing
support among the public, encouraged by anti-vaccination groups, the
vaccine was pulled from shelves.
It’s disappointing to see that an effective vaccine was withdrawn due
to lawsuits and poor sales fueled by pressure from anti-vaccination
groups and fear-mongering from the media, all the while the burden of
Lyme disease has continued and even worsened. This highlights the need
for better public education around important topics such as this, which
seems to be an ongoing issue that is not going to be easy to tackle when
battling against the blessing and curse that is the internet.