We've nearly wiped out the Guinea worm. Not usually fatal, but a nasty little fucker. What's cool is this was done entirely though education and logistics, no vaccine or special pill at all. Not enough kudos can go to President Carter, Carter Center, and everyone else involved, for their efforts.
Also fun fact, in the long run this actually has a negative cost.
In other words, for every $1 invested in the campaign, $1.29 came back in the form of greater agricultural output and earnings.