Feral Stage
From Halopedia, the Halo wiki
The Feral Stage is the first phase of a Flood infection, in which host bodies of other species are taken over by an Infection form [1]. In this stage, hosts are mutated into Combat Form. Once the Gravemind commanding the infection has mutated enough hosts, the infection can progress to the Coordinated Stage. The last two stages are the Interstellar Stage and the Galactic Stage.
