In nematodes and humans, mitochondrial stress in the nervous system initiates a whole-body response that is most pronounced in the gut. A recent study showed that in nematodes, the odor of a pathogen triggers the nervous system to broadcast this response to the rest of the organism, prepping mitochondria in intestinal cells to fight a bacterial infection. Humans, too, may be able to sense pathogenic odors that prepare the gut for an infection.