Pathogenesis: A History of the World in Eight Plagues

by Jonathan Kennedy

The fact that European attempts to settle in the Americas foundered without the help of infectious diseases suggests that the Portuguese would have struggled to colonize West Africa even if malaria and yellow fever hadn’t intervened to help the indigenous population. But these mosquito-borne diseases created a defensive force field that made military conquest all but impossible. Writing in the sixteenth century, João de Barros, the historian who is referred to as the “Portuguese Livy,” lucidly captured the frustrations of the would-be colonists: But it seems that for our sins, or for some inscrutable judgment of God, in all the entrances of this great Ethiopia that we navigate along, He has placed a striking angel with a flaming sword of deadly fevers, who prevents us from penetrating into the interior to the springs of this garden, whence proceed these rivers of gold that flow to the sea in so many parts of our conquest.[74] In the late eighteenth and early nineteenth centuries, when Britain was on its way to becoming the dominant colonial force in the world, malaria and yellow fever—the flaming sword of deadly fevers—still made tropical Africa all but unconquerable.