When you think of how to stop a major disease outbreak, you’re probably thinking of a
scene from a medical thriller; where a world renowned virologist is helicoptered out in
a race against time to find the person who’s the source of the infection.
The Patient Zero.
Patient Zero isn’t just a Hollywood creation.
It’s a real thing in the medical community and it identifies the first carrier of a disease
in an outbreak.
Identifying the origin of a disease helps scientists understand and prevent future pandemics.
These things have to start somewhere.
But figuring out who Patient Zero is requires a great deal of detective work.
Health experts go out into the field and map the transmission of a virus.
They follow a molecular game of telephone (called contact tracing) which involves searching
for everyone who came into contact with a sick patient.
According to an epidemiologist we spoke to, it’s helpful to find out how a virus travels
through a community.
It’s a way to classify the disease (as airborne or foodborne for instance) and work on a vaccine.
Though movies tell a different story, finding Patient Zero isn’t as big a deal as preventing
an outbreak from spreading.Plus… searching for the scapegoat in situations like this
can easily turn into a public witch hunt.
For example, back in the 1980s during the height of the AIDS epidemic, researchers at
the CDC interviewed several HIV patients looking for the source of the infection.
They constructed a network of 40 infected men.
All 40 were connected to one gay airline flight attendant who was then vilified and dubbed
Patient Zero of the AIDS epidemic by the media.
But, it wasn’t that guy.
Later, genetic analysis found HIV had been floating around the US throughout the 1970s,
evolving within different hosts for years.
Science exonerated him!
In fact, he’s so not patient zero.
A separate genetic analysis found the actual patient zero has roots that go all the way
back to chimps in Africa... people were slaughtering them for their meat, exposing themselves to
the HIV virus…
Which is common, many diseases start in animals and then move over to humans, otherwise known
as spillover.
MERS came from camels, SARS from bats, and H5N1 or bird flu from birds…
When they come in contact with humans, a disease is considered zoonotic, and can be very deadly.
But, to bring it back to finding patient zero...
Remember, epidemiologists want to contain the outbreak, not find someone to blame.
Which is why the process of shoe-leather epidemiology is a big deal.
Scientists go out and find who did what, when and where.
It’s very much like a detective novel for the path of a disease.
Finding wider connections is important because of something called the 20/80 Rule..
Basically, 20 percent of a population causes 80 percent of infections -- that 20 percent
has a name: Superspreaders.
Superspreaders are the ones who make a virus, well, go viral.
The SARS and ebola outbreaks both had superspreaders, that flight attendant was very likely a superspreader.
In 2011, there was an outbreak of methicillin-resistant staphylococcus aureus, or MRSA, a superbug
in a baby ward.
By using fast genome sequencing technology, a team of researchers were able to work quickly
to trace the source to a staff member who was unwittingly carrying the strain and infecting
patients -- they’re not patient zero, but the PZ didn’t matter.
The outbreak was contained.
Let’s face it, looking for Patient Zero can be difficult and problematic, because
there’s really no way to actually observe the moment when patient zero becomes Patient
Zero.
It’s really more of a good theory with the best evidence we’ve got at the time.
But with new computer simulations, genetic tracking and good ol’ fashioned detective
work, health workers can find the superspreaders who really drive the epidemic, putting a stop
to a disease before it spreads further.
Disease eradication is a seriously difficult business, but we’ve done it… haven’t
we?
Kind of.
We eradicated smallpox -- find out how, in this blast from the past, here.
Why was I in a sweater?
And that hair?
What is happening?
What was your favorite movie about the spread of infections.
Let us know.
Please subscribe so you get more Seeker. I went on a date once to see Contagion.
We shook hands and never saw each other again.
Thanks for watching.