Guardian - Part 6 (Patreon)

Elsa was now leading the way through the vents of the ship. Her objective was to reach the nearest escape pods and hope that the water flooding didn't sabotage any of the emergency systems.

The Security Replica also told Abby what she knew about the parasite spreading: several kind of creatures. Parasite eggs, spider, bigger creatures like she killed previously. She also witnessed that these creatures were feeding upon the women of the ship. Injecting a poisonous...Well...Semen for lack of a better description.... into them and draining them dry of any fluids of their own.  

To conclude: parasite was seeking any female on board, killing them in order to feed...And to breed.

In addition, the presence of a cold fog and atmosphere was also a hint that there was a parasite in the area.