A long, long time ago in a galaxy far, far away... Oh wait, this isn’t fiction. Or Star Wars. A not-so-long time ago, on an island not-so-far away, it literally rained cats. Cats in parachutes. Yep. ( image source ) In the early 1950s, Borneo was affected by a serious malaria outbreak. The World Health Organization, as part of their antimalarial campaign, sprayed houses on the island with insecticide DDT to kill the mosquito vector responsible for the spread of the disease. And it worked, the number of cases of malaria reduced. However, there were some other serious consequences.