Not quite -- we simply drew down the population of Anopheles enough that malaria was unable to spread. DDT is a very effective insecticide, but resistance has been described and can spread if it is overused; in fact it is estimated that agricultural use of DDT causes more deaths from malaria by contributing to DDT resistance in Anopheles and thereby affecting vector control operations.

See: http://www.nature.com/nature/journal/v293/n5829/abs/293181a0... -- http://localhostr.com/file/itFWMaa/zzz.pdf

"it can be estimated that at current rates each kilo of insecticide added to the environment will generate 105 new cases of malaria"

In short, it just ain't that easy.