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“The cautionary point is this,” write Gretchen Daily and Paul Ehrlich, biologists at Stanford University. “Any major land-use change is likely to alter the epidemiological environment in ways that are often difficult to predict.” Deforestation is the prime example. (Reforestation can cause problems too: See “Trees, Ticks and Spirochetes” to learn how young fragmented forest contributes to the spread of Lyme disease.
Stories From the (Missing) Jungle:
Here are some more tales that illustrate the link between losing forest and losing ground to infectious disease:
Malaria:
The microbe that causes malaria, predominantly Plasmodium falciparum, was identified long ago, as was its mode of transmission, various species of Anopheles mosquito. For centuries, malaria was treated by quinine, a natural plant extract, and, since World War II, by several synthetic antimalarials, including chloroquin. Draining swamps, installing screens, and educating people about disease transmission greatly reduced the incidence of the disease earlier in the century. But changes in the landscape and living patterns have caused a global resurgence, a situation labeled “serious and becoming worse” by the World Health Organization. Growing resistance to insecticides and to antimalarial drugs are major problems too, and new antimalarial drugs are increasingly expensive.
A potentially fatal infection, malaria currently threatens 40% of the world population in 100 countries and territories, making it the most significant parasitic disease affecting humans. Countries in tropical Africa account for more than 90% of the total incidence and the great majority of deaths from malaria.
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