Anyone who has ever received a yellow fever shot (as I did in 2008 for a university trip to Kenya) can describe that weird moment when the nurse informs you that approximately 1 in 300,000 people who receive the vaccine will develop a version of the disease, probably fatal. However, if you choose not to be vaccinated, as a nonnative traveler you are a walking target for carrier mosquitoes. Most of us roll up our sleeves and take our chances with the vaccine.
Now, in Mosquito Empires: Ecology and War in the Greater Caribbean, 1620-1914 (Cambridge University Press), historian John McNeill takes us to a time when, as a soldier or a commander, you might watch tens of thousands of your comrades die of yellow fever or malaria, and when going into a particular part of the world such as the Caribbean almost guaranteed this outcome. In the 1720s this was just the cost of doing military business abroad. And to think that military history has been determined as much by bugs as guns.