Measles
I've been very disappointed to see that Obama, McCain, and Clinton all jumped on the "I am suspicious of vaccinations" bandwagon. All over the US, people are drifting away from vaccinating their kids. But the evidence is that vaccinations are safe - and we really do not want the old diseases back, the ones that used to prey so heavily on children - like Measles (you have to click past an ad to read the article).