Next time you get bit by a mosquito, do not swat him. Rather, thank him for your freedom! Yesterday marked the 229th anniversary of George Washington’s victory over the British at Yorktown, which meant that American independence was won. This fascinating piece by J. R. McNeill credits the lowly and much-hated mosquito for this otherwise unlikely turn of events:
Major combat operations in the American Revolution ended 229 years ago on Oct. 19, at Yorktown. For that we can thank the fortitude of American forces under George Washington, the siegecraft of French troops of Gen. Jean-Baptiste Donatien de Vimeur, the count of Rochambeau – and the relentless bloodthirstiness of female Anopheles quadrimaculatus mosquitoes.
Those tiny amazons conducted covert biological warfare against the British army. Female mosquitoes seek mammalian blood to provide the proteins they need to make eggs. No blood meal, no reproduction. It makes them bold and determined to bite.
Some anopheles mosquitoes carry the malaria parasite, which they can inject into human bloodstreams when taking their meals. In eastern North America, A. quadrimaculatus was the sole important malaria vector. It carried malaria from person to person, and susceptible humans carried it from mosquito to mosquito. In the 18th century, no one suspected that mosquitoes carried diseases.
Malaria, still one of the most deadly infectious diseases in the world, was a widespread scourge in North America until little more than a century ago. The only people resistant to it were either those of African descent – many of whom had inherited genetic traits that blocked malaria from doing its worst – or folks who had already been infected many times, acquiring resistance the hard way. In general, the more bouts you survive, the more resistant you are.
The article goes on to explain how the British troops, with no immunity to malaria, were incapacitated by the disease, while the colonial troops, especially the Southerners who had already survived bouts with the mosquito-borne malady, were relatively immune.