It begins with a seemingly harmless mosquito bite. Within a few days, you start to feel chills, followed by paralysis in the joints, fever and sweating; a coma may follow. In fact, every 30 seconds—the time it takes you to read this paragraph—someone around the world dies from malaria.

Typically, the disease is confined to tropical regions, home to a disproportionate amount of the world's poor. However, as climate patterns change, so too do patterns of outbreaks.

Nicky Wimble/Oxfam

Sen Sles, of Lovethom Village, Cambodia, contracted malaria from mosquitoes while collecting firewood to sell. "I had no choice but to enter the forest,” he says.

Diseases like malaria, transmitted via intermediary hosts (mosquitoes, predominantly), are most sensitive to long-term climate change. Research shows that variations in temperature and rainfall influence the size of mosquito populations; types of habitats in which they breed; incubation period; and survival of the malaria parasite they carry.

Global Impact member charity Oxfam America reports that irregular rainfall over the past three years has caused recurring flooding and record cases of malaria in Cambodia’s Kratie province, bordering the Mekong River. Besides destroying rice crops, the floods left behind pools of stagnant water—perfect breeding grounds for mosquitoes.

After floods leveled his rice paddy, Sen Sles was forced to collect and sell firewood in forests to support his family of five. “I own a very small plot of land, which normally is not enough for my family’s consumption, but this year the irregular flooding destroyed almost everything, and I had no choice but to enter the forest,” he says.

In the forest, Sen contracted malaria. “I feel bad; I have a very high temperature but I have no money to buy more medicine.” Excessive deforestation due to wood harvesting is beginning to drive mosquitoes into surrounding villages, placing even more people at risk.

Similar outbreaks are arising in highland countries thought to be too cool for malaria, including Cameroon, Papua New Guinea, Madagascar and Kenya. This is a heated global issue, to be sure, and the topic is up for discussion at the United Nations-led climate summit this week (March 31-April 4) in Bangkok, Thailand.

“Let us recognize that the effects of climate change affect us all. And that they have become so severe and so sweeping that only urgent, global action will do,” said UN Secretary General Ban Ki-moon. “We are all in this together. We must work together.”