Mosquito Empires: Ecology and War in the Greater Caribbean, 1620-1914

Article excerpt

J. R. McNeill Mosquito Empires: Ecology and War in the Greater Caribbean, 1620-1914 New York: Cambridge University Press, 2010, xviii + 371 pp.

On 13 March 1741, a British fleet arrived at Cartagena with 29,000 soldiers and sailors to launch what was then and may still be the largest amphibious assault in world history. The port city of 10,000 was defended by some 4,700 men. The odds would seem to be in Britain's favour. Yet two months later the remains of the British forces were at Jamaica. All told, the British lost some 22,000 men, but only 1,000 from wounds inflicted in actual warfare. Meanwhile, the Spanish force lost only a few hundred men. How can we explain this? March is the start of the rainy season in coastal New Granada, and when the rains came they hatched a fresh crop of mosquitoes capable of carrying the yellow fever virus. General immunity to the virus is earned by children who survive its more mild manifestation, and yellow fever won't thrive among a 70% immune population. It turns out the overwhelming majority of the British forces had only recently come to the Caribbean whereas only 15% of Spanish forces were newly arrived. In this imperial battle and several others before the 1770s, differential immunity to yellow fever worked to defend the Spanish empire from its rivals. By the last quarter of the 18th century, however, the virus was aiding revolutionary movements. All of this was possible, argues J. R. McNeill in his magisterial new book Mosquito Empires, because the ecology of disease vectors--particularly that of the yellow fever virus and secondarily the malaria parasite--influenced the outcome of warfare in the Greater Caribbean from Suriname to the Chesapeake over a 250-year period. This was a time before effective control programs were developed by US scientists in Cuba and Panama at the turn of the 20th century.

The argument is not entirely new, but it has never been told so well nor so convincingly. McNeill masterfully buttresses a staggering array of primary sources from England, Scotland, and Spain with both numerous secondary works that cover distinct regions and empires and disciplinary studies covering epidemiology, medicine, and entomology over a 300-year period. McNeill shows that a new "creole ecology" in America allowed yellow fever and malaria to take hold with significant consequences. The result is a true environmental history, a work that sees the environment not as a stage upon which the human drama plays out, but as an entire ecological system being modified by people and influencing them in turn.

Yellow fever and malaria are native to Africa but are transmitted by two genera of mosquitoes, the Aedes and Anopheles respectively. Although there were many Anopheles in the Americas before 1492, none carried malaria until African slaves brought the plasmodia over in their blood, constantly reintroducing it. Among the most effective at carrying the plasmodia was An. quadrimaculatus, a North American species that was newly nourished by the blood of introduced livestock and thrived in transformed landscapes typical of rice plantations in the Carolinas. In contrast, one species of Aedes, A. aegypti, transmitted the yellow fever virus. It arrived on slave ships from African ports where yellow fever was endemic. McNeill shows how several ecological factors came together to aid A. aegypti's toehold in disturbed environments such as sugar plantations and port cities. Tropical climate cycles, the need to store water, forest clearing and the removal of mosquito predators such as birds, A. aegypti habits and preferences, El Nino cycles, human densities in urban areas, and even the low-stooping labour of cane cutting are all used to explain how A. aegypti interacted with populations to ensure that the yellow fever virus flourished in the Neotropics.

But, as noted above, yellow fever is not deadly to children, and survival confers immunity. This outcome created a "herd immunity," weakening the ability of the virus to spread among creole populations but at the same time allowing it to ravish large newcomer groups. …