But stagnant water occurs after every rain, say the leaf that is cupped to hold a few drops of water.

But you are correct; global warming is making malaria far less likely in the west be producing long peroids of drought.

But in the midwest, all the heavy rains which a flooding towns and making people homeless may well make those areas where malaria can spread.

While malaria in humans is spread from human to human, isn't either a bacteria or virus, another class of disease is a virus that is spread by mosquitos from bird to human in many cases, others are spread from human to human by mosquitoes. In NH we are warned about Triple E and West Nile, both spread by mosquitoes from birds. Related to the latter are Yellow Fever and Dengue fever. Dengue is a problem in the US in the territory of Puerto Rico, and in places Americas like to go, like Brazil and Monterey, Mexico - not exactly impoverished areas. Yellow Fever caused 5000 death in Memphis near the end of the 19th century.

And the mortgage collapse has certainly created lots of pools of stagnant water. I suppose you can call those neighboods of foreclosed houses with many having pools impoverished, but that isn't the typical use of the term.

All of these mosquito spread diseases have two other things in common, no prevention and no treatment.

In most of the US, the population of infected mosquitoes is reduced to near zero in the fall, and it takes a while for the new disease free mosquitoes in the spring to pick up the disease. This isn't the case in places where these diseases are a public health problem with some regularity. While some argue global warming will improve the climate of much of the US by eliminating winter, that brings with it the increased risk of these diseases. Unless the warmer climate is also drier and the midwest turns to desert or to a new dust bowl.