Breathless: The Scientific Race to Defeat a Deadly Virus

by David Quammen

George Macdonald studied malaria, a very complicated disease caused by a protozoan that passes from host to host in the bites of mosquitoes, and the R0 for that microbe depends on several factors, such as the density of mosquitoes, their longevity, how many times each mosquito may bite, and how long an infected human remains infectious to other mosquitoes. The reproduction number could be wildly various, Macdonald noted, ranging from 1.0 upward to who knows what. If there were long-lived and voracious mosquitoes biting people with long-enduring active infections, it might be 735. No wonder Macdonald and his public health colleagues couldn’t eradicate malaria, and seven decades later the disease still kills almost a half million children each year.