Spillover: the powerful, prescient book that predicted the Covid-19 coronavirus pandemic.

by David Quammen

the level of human jeopardy depends on other factors besides the geographical ranges of the mosquitoes and the monkeys. It depends on whether those mosquitoes come out of the forest to bite humans, and whether people go into the forest to be bitten. It depends on whether sizable expanses of forest are left standing within that region and, if not, how the mosquitoes react. As deforestation proceeds, do the forest mosquitoes go extinct, or do they adapt? It depends on whether the parasite becomes so well established within human populations that monkey hosts are no longer necessary. It depends on whether the parasite colonizes a new vector, achieving transmission via some other kind of mosquito—members of a species more willing to seek out humans in their longhouses, their villages, their cities. In other words, it depends on chance and ecology and evolution.