Environmental changes have always been associated with the appearance of new diseases or the arrival of old diseases in new places.

the direction of change -- whether the diseases will increase or decrease -- is much more difficult to predict, because disease transmission involves many factors

One impact of rising global temperatures, though, can be fairly accurately predicted,

malaria is not transmitted above a certain altitude because temperatures are too cold to support mosquitoes. As temperatures rise, this malaria line will rise as well.

Another change could be the flu season.

as new areas lose their seasons they may also begin to see influenza year-round.

extreme weather events will also lead to more disease

high intensity storms have exacerbated an aging drinking and wastewater infrastructure, enhanced the mixing of untreated sewage

If agriculture in a particular area begins to fail due drought, more people will move into cities,

with an increased transmission of a variety of diseases