Its like the coronavirus, when the pandemic started. Each and everytime someone reported that "a case" appeared, I was certain that there were actually 10 more than that. Once a virus shows up in a population, you'll only notice some people showing symptoms within a certain amount of time, while others simply haven't displayed signs of infection yet.

At some point, Containment of the disease can only go so far, unless you're willing to use ever more force to keep people in place (since they'll characteristically refuse to do what they're told), or just straight-up kill them to save the rest of the population.

But, people aren't chickens.