Out of the millions of fungal species in the world
only a few hundred can make people sick.
Coccidioides is one of them.
Its spores can sometimes cause
pretty serious infections in humans.
But that's not the weirdest thing about this fungus.
Most fungi prefer dark, damp
and relatively cool conditions...
but this one has found a way to live in the desert.
And while most fungi eat dead or decaying material...
cocci doesn't always wait for an animal to die...
before it starts digesting them from the inside out.
Drama aside, this fungus has existed for millennia
and yet there's still so many things
we don't understand about it.
Like exactly where it is at any given time...
or how it spreads in the soil...
because it is spreading.
And we can only guess why.
The infection caused by cocci goes by many names.
Coccidioidomycosis.
Desert Rheumatism.
San Joaquin Valley Fever.
Or just Valley Fever.
Its symptoms are similar to that of the flu
except that general achey-ness, fever fatigue, and more
can last for over a month.
Others develop fungal pneumonia
but some can develop something far worse
like chronic lung disease, skin absences or meningitis
which can be fatal.
Fortunately, only about four in ten people
ever develop symptoms at all and outbreaks are pretty rare.
Right now, 97% of US Valley Fever cases
occur in Arizona or California.
But...
Not all states report.
So Texas is one of those areas that...
you know, they just don't report the disease nationally
in spite of being probably a hotspot.
In 2019 states officially reported
20,000 cases of Valley Fever to the CDC.
Some researchers think that actual number
is closer to 350,000 cases annually.
If you account for underreporting and misdiagnoses.
Where it is reported...
cases are rising year after year...
with California reporting a 159% increase
from 2013 to 2019.
And it's being found in more places.
Cocci is typically found in the soil in the southwestern US
parts of Mexico, Central, and South America.
But in 2014, researchers found it in Washington State.
It's likely the fungus itself is already lurking in the soil
in states outside of this range.
And if that's not unsettling enough
we're not really sure how it's moving...
or where exactly it's going next.
Scientists think there might be three separate systems
driving the spread of this mysterious fungus.
Let's start with some bizarre features of cocci itself.
It has two forms:
An environmental form that lives in the desert soil.
So the fungus in the dirt grows as a mold.
Sort of not so different
from what you see on bread when it gets old.
But like, we're talking lightweight, microscopic mold
that grows very slowly in soil, making it hard to track.
When the soil is disturbed
like when dust storms sweep through the west
or when construction workers begin digging a foundation...
cocci releases spores into the air
where unsuspecting mammals breathe them in.
Once inhaled, it settles into the lungs
where those spores somehow morph into a new form...
a parasitic form that multiplies in your body
and grows to a size much larger than its environmental form.
Through a series of cues that we actually don't
really understand all that well, it can be like 100 microns.
You can see the lesions
in infected lung tissue with the naked eye.
Some people who inhale these spores
get the symptoms of Valley Fever.
But sometimes, somehow, and this is what's really weird...
it can go dormant in your lungs.
You actually develop
residency of that fungus somewhere in your body.
Being dormant is a great strategy, right?
You're not using many resources.
The host isn't recognizing you because you're not actively
growing and irritating the host.
Yeah. Then you just bide your time.
Cocci isn't picky about what kind of lungs it's settling in.
Infections have been found in almost any type of mammal
from humans to dogs to dolphins.
Which brings us to the second thing that’s possibly helping this fungus spread:
Desert rodents and something called the Endozoan Hypothesis.
I hope you're ready to talk about dehydrated rats.
It works like this.
A kangaroo rat or some other desert rodent
inhales cocci while digging its burrow.
The cocci either lays dormant in their lungs
or the infection kills them.
At that point
the fungus is the first on the scene to devour the dead animal.
And by devour
I mean digest its dead body until there's nothing left.
Fun fact this is what cocci is doing to people
with severe valley fever.
While they're alive.
Their spinal column is being digested by this organism.
And it just freaks me out.
Either way, it's the first one on the scene.
Not even you're the best competitor
or you're the best at doing anything.
It’s just, you're there first.
And so maybe that's cocci’s strategy.
When the rodent dies, cocci is released
back into the soil and morphs back into its environmental form
where it waits to be kicked up and inhaled by some other host.
If this is the case, then the more desert rodents
living and dying, the more likely cocci can move through the soil.
Which brings us to our third related factor:
Extreme weather.
Isn’t is always?
Heavy rains have been unleashing on the desert
resulting in booms of vegetation.
The surplus food leads to a surplus of rodents...
plenty of hosts to breathe in the fungus.
But the desert ultimately returns...
to a desert and heavy drought wipes out more and more
of these infected rodents.
When they die, cocci spread right back into the soil
and the system starts again.
But we still don't know if this is actually even happening...
because of how little we understand about cocci itself.
Proving the Endozoan Hypothesis would be a colossal effort
that involves strapping trackers to a bunch of desert rodents.
And finding cocci in the soil at all has proven difficult.
The current tests don't always detect it in the soil...
even when it's there.
Ultimately, cocci’s spread spread could be thanks to all of these factors combined
but there are still tons of unresolved questions.
What we do know is that the US
is getting warmer and that on its own could expand cocci’s range
potentially making more people sick.
One study estimates that cocci’s range
could more than double by 2095...
due to increasing arid conditions across the US.
Pair all of this with rising rates of construction in the desert...
and population booms in cities like Phoenix.
And it's no surprise that Valley Fever cases
are on the rise.
Researchers have another area of study right now: Prevention.
We have identified a vaccine candidate...
that is both safe and protective, very protective to mice.
And now we've shown that in experimentally infected dogs...
it protects them as well.
And that vaccine is on its way.
But listen, despite my seemingly best efforts
this piece doesn't really exist to scare you
or to get you to hyper focus on one specific freaky infection.
This single fungus is one of a million examples
of how our world is changing in small and mysterious ways...
and how difficult it can sometimes be
for science to keep up.