Jim Hines Terminal Alliance. Book 1 of the Janitors of the Post-Apocalypse
Disclaimer: if you don’t like the Almighty Janitor trope, poop humor, or sanitation engineering in general, this one may not be your cup of tea.
Backstory is that there was a plague that resulted in mindless feral humans with a lower body temperature. Then the aliens came. They developed a cure, and found a useful, tough-to-kill ally. Enter our plucky group of protagonists serving aboard the EMC Pufferfish, as sanitation technicians. Yeah, EMC ships are named after really dangerous Earth wildlife.
Things happen: anyone not in biohazard suits gets exposed to something, the alien bridge crew dies, and the human crew all go feral. Leaving our protagonists with the task of avoiding violent mindless humans, finding out what caused this, and avoiding being permanently decontaminated.
Along the way, we see the power of fixing things, blackmail with fluid lines, and the adage of the E1 in general
Solid humor science fiction.