Malaria cases increase with deforestation, researchers have found, while new roads through the rain forest provide corridors for the migration of people, insects and animals that serve as intermediate hosts for pathogens, Wilson said.
Amid this web of causes and effects, developing countries must define policies that make the best use of scarce resources. While providing safe drinking water or treating wastewater might seem more pressing, failing to prevent climate-related health problems will also have a cost, Corvalán said.
Dr. William Checkley, a disease control and epidemiology specialist at the Johns Hopkins School of Public Health in Baltimore, found that wintertime admissions to the oral rehydration unit at the Children's Health Institute in Lima, the country's largest public children's hospital, doubled during the 1997-1998 El Niño.
"It changed winter into summer," he said, allowing the bacteria and parasites to flourish. Checkley estimated that the 6,225 additional cases of diarrhea attributable to El Niño cost $277,000 to treat.
Having access to climate and disease data allows health officials to target their policies. Because bartonellosis cases also spike a few months after rising temperatures are registered, there is time to spray for sand flies in endemic areas, said Nelson Solórzano, who heads the bartonellosis unit at the hospital in Caraz
The best investment now, Wilson said, would be in setting up regional surveillance networks of climatologists, entomologists and experts in human, animal and even plant diseases.
"If you don't have a network in place," she said, "it becomes hard, when there's a crisis, to respond immediately."
This article originally appeared at The Daily Climate, the climate change news source published by Environmental Health Sciences, a nonprofit media company.