What makes tuberculosis (TB) the world's most infectious killer? - Melvin Sanicas
In 2008, archeologists uncovered two
9,000-year old skeletons.
There’s no definitive way of knowing what
killed these ancient people,
but we do know their bones were infected
by an all too familiar bacterium.
The ancient Greeks knew its consumptive
effects as phthisis;
the Incans called it chaky oncay;
and the English called it tuberculosis.
Today, tuberculosis, or TB,
is still one of the world’s biggest
infectious killers,
causing more deaths than malaria or
even HIV and AIDS.
But what exactly is this disease, and how
has this pathogen persisted for so long?
Typically, TB bacteria called
mycobacterium tuberculosis, are airborne.
They travel into our airways and
infect our lungs.
Here, immune cells called macrophages
rush to the infection site,
attempting to absorb and break down
the bacterial invaders.
In many cases, this response is enough
to remove the bacteria.
But in individuals with other
medical conditions–
ranging from malnutrition and HIV to
diabetes and pregnancy
–the immune response may not be
strong enough to destroy the intruder.
If so, mycobacterium tuberculosis will
reproduce inside those macrophages,
and form colonies in the
surrounding lung tissue.
As they infect more cells,
the bacteria employ cell-degrading enzymes
that destroy the infected tissue,
triggering chest pain, and causing
patients to cough up blood.
The damage to the lungs leads to
oxygen deprivation.
This begins a flood of hormonal changes–
including a decrease in appetite and
iron production.
From here, microbes can spread to the
skeletal system,
causing back pain and difficulty moving;
to the kidneys and intestines,
causing abdominal pain;
and to the brain, causing headaches
and even impaired consciousness.
These symptoms produce the
classic image of TB:
weight loss, a hacking, bloody cough,
and ashen skin.
This ghostly appearance earned TB
the title of the ‘White Plague’
in Victorian-era England.
During this period, tuberculosis was
considered a ‘romantic disease,'
because it tended to affect poverty-
stricken artists and poets–
those with weaker immune systems.
TB’s outward symptoms even helped
fuel the popular myth of vampirism.
In spite of– or perhaps because of
these less than scientific concerns,
this period also marked the first strides
toward curing TB.
In 1882, the German physician Robert Koch
identified the disease’s
bacterial origins.
13 years later, physicist Wilhelm
Roentgen discovered the X-ray,
enabling physicians to diagnose and track
its progression through the body.
These techniques allowed researchers to
develop reliable and effective vaccines–
first for smallpox, and again in 1921,
when scientists developed the BCG
vaccine to battle TB.
These developments laid the groundwork
for the modern field of antibiotics–
currently home to our most effective
TB treatments.
But, antibiotics fail to address a major
diagnostic complication:
about 90% of people infected with TB
don’t show any symptoms.
In these latent infections, the TB
bacterium may be dormant,
only activating when someone’s immune
system is too weak to mount a defense.
This makes TB much harder to diagnose.
And even when properly identified,
traditional treatments can take
up to 9 months,
requiring multiple drugs and a high
potential for side effects.
This discourages people from finishing
the full course,
and partial treatment enables bacteria to
develop resistance to these drugs.
Today, the disease is still prevalent
in 30 countries,
most of which face other health crises
that exacerbate TB and
trigger latent cases.
Worse still, accessing treatment can
be difficult in many of these countries,
and the stigma towards TB can discourage
people from getting the help they need.
Health experts agree we need to
develop better diagnostics,
faster acting antibiotics, and more
effective vaccines.
Researchers have already developed a urine
test that yields results in 12 hours,
as well as a new oral treatment that could
cut treatment time by 75%.
Hopefully, with advancements like these,
we’ll finally be able to make TB
exclusively a thing of the past.
