So, I get why you're saying this, but it's actually a very well studied problem in business. Basically, let's imagine you're the Carter Foundation and you have

So, I get why you're saying this, but it's actually a very well studied problem in business. Basically, let's imagine you're the Carter Foundation and you have found a way to treat the 30 cases a year exhaustively and prevent any meaningful spread for 2M$/year, and it's expected to stay flat over the rest of the future. Let's say you have a one time cost to get rid of the remaining worms of 10M$. Well, it's almost certainly a good idea to get rid of the worm's then, it costs 20% as much to treat next years infections as it does to eradicate them eternally! Instead consider if it would cost 1B$ to eradicate them. Still a good thing to do... but the interest from 1B$/year is about 50M$ (order of magnitude). You could keep guinea worms completely eradicated and give away 48M$ to other things indefinitely. (This is effectively the same calculation and efficient business should make for most any decision. Is the internal rate of return on this decision good enough to earn the money to do it.)