The formula is easily understandable, not that anybody is going to do anything about it. The solution is simple, not that anybody is going to do it. Overpopulation in Mexico has led to more clearing of the southern forests to make room for grazing land for cattle. ‘Cause you gotta feed all those extra people, don’t you? Those forests, though, are the natural habitat of the Vampire Bat. (Actually there are more than one kind of Vampire Bat, but for the sake of the present conversation we can refer to them collectively.) More people living in areas that are the bats’ natural habitat means that more people are going to get bitten by them. Which means that, despite the fact that only a miniscule percentage of the Vampire Bat population carries rabies, more people are going to end up with rabies. What’s the solution? Stop overpopulating. Simple as that. And this doesn’t mean, as some people mistakenly think, not having children. If a couple has no more than two children, they are not contributing to the population problem, as they are only replacing themselves. (No offense to folks who come from big families, but nobody needs more than two children.) But Mexico is a predominantly Catholic country, and for some reason Catholics are against using birth control. That means we get more bat/human encounters. And more rabies.
Though they are not overpopulated, Vampire Bat populations are on the rise as well. We might even end up with Vampire Bats in the southwestern US someday. Personally, I’m okay with living in a world where there are more Vampire Bats. Just keep your windows closed at night. You’ll be fine.