it's from subnautica.

Carar is an alien bacterium created by the Precursor race[1] for unknown reasons. It seems to have completely taken over Planet 4546B. It is described in the Degasi PDAs as "part of the ecosystem", with further suggestions that the Degasi survivors were infected at some point - as stated by Bart Torgal while discussing the flu-like symptoms the crew was experiencing. Early on, the player's PDA and Lifepod will make note of the high levels of bacterial infection in the water.

It is stated in Precursor data that the Carar bacterium has killed over 143 billion creatures over the course of time since it's creation. After a Sea Dragon Leviathan damaged the Disease Research Facility in an attempt to retrieve its offspring, the previously contained Carar bacterium was released onto the planet. This decimated the planet's ecosystems, as much of the life on the planet died due to the bacterium's immuno-repressive behaviour and genetic corruption. This prompted the Precursors to initiate their emergency quarantine: activating the Quarantine Enforcement Platform. The Quarantine Enforcement Platform shoots down all approaching or departing spacecraft to prevent Carar being spread to other planets.

The PDA estimates that Carar incubates in two weeks and kills in five weeks - it accomplishes this by shutting down the immune system (already making the infected host susceptible to other diseases) and causing genetic damage to the host's DNA, eventually leading to a total shutdown of the organism due to its inability to keep functioning properly.