“
Her answer was immediate: “Climate change.” As the United States becomes warmer, she said, the ranges of the sand fly and the wood rat are both creeping northward, the leish parasite tagging along. The sand fly genus known to spread this kind of leish has now been found in the United States five hundred miles northwest and two hundred miles northeast of its previously established range. A recent study modeled the possible expansion of leishmaniasis across the United States over the next sixty-five years. Since it takes both vector and host to spread the disease, the scientists wanted to know where the sand fly/wood rat combination would migrate together. They looked at two future climate scenarios, best case and worst case. For each case, they extrapolated out to the years 2020, 2050, and 2080. Even under the best-case climate assumptions, they discovered that global warming would push leishmaniasis across the entire United States into southeastern Canada by 2080. Hundreds of millions of Americans could be exposed—and this is just by wood rats. Since many other species of mammals can host the leish parasite—including cats and dogs—we know the potential problem is far greater than what was described by this study.* A similar spread of the disease is expected in Europe and Asia. It seems that leishmaniasis, a disease that has troubled the human race since time immemorial, has in the twenty-first century come into its own. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the NIH, told our team bluntly that, by going into the jungle and getting leishmaniasis, “You got a really cold jolt of what it’s like for the bottom billion people on earth.” We were, he said, confronted in a very dramatic way with what many people have to live with their entire lives. If there’s a silver lining to our ordeal, he told us, “it’s that you’ll now be telling your story, calling attention to what is a very prevalent, very serious disease.
”
”