In HBO’s upcoming TV series adaptation of The Last of Us, 60
per cent of humanity is wiped out by the genus of parasitic fungus Cordyceps- a rare brain disease that causes genetic mutation and turns its host into a

The trailer of the upcoming TV-series was
released on September 26, 2022. The Last of Us will star Pedro Pascal, Nick Offerman, Murray Bartlett,
Bella Ramsay, Anna Torv, Gabriel Luna, and Melanie Lynskey. It is scheduled to
premiere in early 2023.

How does the Cordyceps fungus work?

A mutant Cordyceps fungus epidemic devastates the United States in
2013, morphing its human hosts into hostile life forms known as the Infected.
The actual cordyceps infection is a mind-controlling infection that grows over
the host’s nervous system and regulates it. The virus takes one to two days to
completely take over its host and is transferred through a bite or the person
inhaling the fungus spores. The Infected, unlike zombies, are not undead but
rather live hosts to the cordyceps pathogen. Because of the way the infection
spreads to the brain, the virus cannot be eliminated from the host without
killing them.

Also Read: The Last of Us zombies explained

If not immediately killed, the host will advance through various
phases of the infection.  Each stage is caused by the progression of time,
and the infected humans will behave in very various ways based on which stage
they are in. The Runner, Stalker, Clicker, and Bloater are the four main stages
seen in The Last of Us. While The Last of Us: Part II confirms that there are
more stages (such as the Rat King), the four main ones are encountered in the
first game. 

Also Read: How Ellie is key to the zombie apocalypse?

Surprisingly, the Cordyceps virus is modelled after a real fungus
that plagues insects. The disease spreads after infecting the host insects,
robbing the bugs of their autonomy and eventually killing them. Infectious
spores spread from the host’s cadaver shortly after, infecting other living
insects. One of Naughty Dog’s teasers even featured a viral clip from BBC’s
Planet Earth that depicted a fungus killing a ‘zombie ant.’

However, all is not lost as it is unearthed that Ellie, a 13-year-old
orphan, is immune to the disease and might be a valuable asset for the
engineering of a vaccine against the epidemic.  It is assumed that if she
was thoroughly studied, a cure or vaccine for the infection could be developed.
But this is never explained, however, because the research would lead to her
death, which her friend, Joel forbids.