Simple the radiation acts as a repellent pheromone. Most insects hunt, mate, and communicate using pheromones. These bugs might use radiation instead and give off a variant of chorniton particles, a type of radiation in flux, as a by-product of their feeding or mating process. Thus the Aging/regressing effect experienced by their host is simply a side effect of the bugs waste. Similar to a host being poisoned slowly with lime disease by a tick.<br/><br/>If we can isolate the radiation that makes Sam immune we would be able to treat everyone with it and kill off and inoculate the crew against future infestation.<br/><br/>What do you think?