At the heart of the Netflix fantasy series is a mysterious ailment known as The Sick.

Since Season 1, The Sick played a major role inNetflix’sSweet Toothseries.

What Is The Sick in Netflix’s Sweet Tooth?

Sweet Tooth Christian Convery as Gus

After three seasons and 24 episodes, the threat of The Sick looms heavy over theSweet Toothseries.

This mysterious disease is at the heart of this DC Comics adaptation, plaguing humanity in a far-flung future.

The Sick is an affliction (also known as H5G9 Virus) that is killing off humans en masse.

A human suffering from The Sick in Sweet Tooth looking sickly with red rings around his eyes and sweat on his brow

Curiously though, The Sick only seems to affect humans, with hybrids being somewhat immune to it.

Those inflicted with the disease are expected to die within three or four days of contracting it.

What Caused The Sick In Sweet Tooth?

A baby hybrid with a big animal ear in Sweet Tooth

Throughout much ofSweet Tooth, the source of The Sick is unknown.

However, this has never been confirmed, and, in fact, is debunked during Season 3.

In Season 3 it is revealed that a tree was the one to blame for The Sick.

Gus looking at the tree on fire in Sweet Tooth

It is this flashback moment that becomes the catalyst for the pandemic that would go on to plague humanity.

Sweet ToothSeason 3 is now streaming on Netflix.

Read more about Sweet Tooth:

Will Sweet Tooth Season 4 Happen?

Sweet Tooth Confirms Purple Flowers' True Meaning In Season 3

Will Sweet Tooth Season 4 Happen? Netflix Officially Confirms the Fate of the Series

Sweet Tooth Season 3 Cast, Characters & Actors (Photos)

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