Yes, they did because various countries have talked to the US about expanding it. The problem is that South America is an enormous place, whereas Panama is a narrow isthmus. It could have been done with some amount of money, but that opportunity ended in 2010 at the latest.
In the end though, history will see it as a half measure where they really shouldn't have half assed it. It only took one moron to defund the project and all of it will come streaming back.
This is a generalizeable problem though, all these conservation efforts, nuclear powerplants etc rely on thr base assumption of a working society there. To really extinct something like the screwworm you need to make it a religous praxis of a cultural orgsnization that persist even when society breaks down.
Hmm, that seems to contradict the article directly - insecticides were used to try to battle screwworm initially and were not really effective - the solution was using sterile male flies to stop reproduction - which would work in South America just as well as it did in North (with sufficient scale)
