The problem is, these places have treatable diseases running rampant for a variety of reasons. There is no one principle cause of ongoing survival problems in various parts of the world today, and no one solution to it either.
Endemic poverty is a complicated social and political phenomena which is maintained due to a variety of causes. Even if tomorrow you eliminated malaria, it's very doubtful the conditions in any country where it's a problem would improve. A case in point is famine - we have more then enough food today to feed a population of 10 billion or more people on the planet fully. But people still starve to death every day. And even when we give food aid for free, we still keep having the same issue - even when we're actively giving it.
When you start trying to order your problems by perceived importance, we get nothing done. Sure you think, I'd hate to die of malaria. But you live in a first world country - if you don't die of malaria, you don't then imagine that you'll still have nothing to eat tomorrow, or that you lack all of the education you take forgranted. Or that there'll be no jobs, or that even if you work hard you'll still be paying bribes just to get a driver's license. Or come the local elections if you don't guess the right side to be seen supporting you'll be murdered or raped, or both.
