World's deadliest killer...

World's deadliest killer...  It's not our fellow man (though he runs a close second): it's the mosquito.

There was a time, in my youth, when mankind was on the verge of winning the war against mosquitoes.  Then Rachel Carson's exaggerated (and sometimes outright false) accusations about DDT led to political action to ban DDT, and that ban indirectly killed more people than all the wars in the 20th century combined.  The effects of that ban are still killing hundreds of thousands of people every year...