DDT and the 100 Million

"In the last days of September 1943, as the U.S. Army advanced to the rescue of Italian partisans — some as young as nine — battling the Germans in the streets of Naples, the enraged Nazis, in a criminal act of revenge against their erstwhile allies, deployed sappers to systematically destroy the city’s aqueducts, reservoirs, and sewer system. This done, the supermen, pausing only to burn irreplaceable libraries, including hundreds of thousands of volumes and artifacts at the University of Naples — where Thomas Aquinas once taught — showed their youthful Neapolitan opponents their backs, and on October 1, to the delirious cheers of the Naples populace, Allied forces entered the town in triumph."

"But a city of over a million people had been left without sanitation, and within weeks, as the Germans had intended, epidemics broke out. [read on]"

Another hundred facts here.
Changing fates of Zika's Aedes aegypti.