“Never in my life, nor in my parents’ and grandparents’ lives, had anyone seen rain like that,” said one MSF nurse from Mozambique whose husband drowned in the floodwaters. “When those in your country watch the landscape from a helicopter, you see the flooded areas and the torn trees, but there is a lot you can’t see. Beneath the waters, below the broken branches, you will find us—our stories and our sadness and our resolve to live.”

We know that with rising waters come the rising risks of waterborne diseases, like cholera. In the aftermath of Cyclone Idai, MSF teams worked around the clock to ensure that people would have access to clean water. We treated more than 4,000 people with suspected cholera and supported a large-scale campaign to vaccinate more than 800,000 people against the disease. The cyclone also left large pools of standing water, ideal breeding grounds for mosquitoes that spread disease. And the waters inundated the fields just before harvest season, destroying an estimated 1.8 million acres of crops and threatening food security in an area where people are already vulnerable to malnutrition.

For every headline disaster, there are ripples of related disasters and attendant medical crises.

With warmer temperatures, rising sea levels, and heavy rains, we can expect to see an increase in climate-sensitive diseases, including waterborne diseases like cholera as well as vector-borne diseases spread by growing numbers of mosquitoes and ticks, such as malaria, dengue fever, and Lyme disease. Malaria already kills more than 400,000 people a year, mostly children under the age of five and overwhelmingly in sub-Saharan Africa. In 2012, 2014, and 2015, MSF teams observed significant spikes in malaria cases in several sub-Saharan countries compared to long-term averages. While the reasons behind these increases are complex—including, fundamentally, inadequate political and financial support for disease control efforts—the weight of evidence suggests that the incidence and prevalence of malaria will increase in Africa and beyond due to climate change.

Honduras, considered a climate change hotspot, is battling its worst outbreak of dengue fever in 50 years following a prolonged rainy season. MSF’s patients are mainly children under the age of 15, and mainly those living in poorer, urban areas. Severe dengue affects most Latin American and Asian countries and is a leading cause of hospitalization and death among children and adults in these regions, according to the WHO. Worldwide, the incidence of dengue has increased 30-fold over the last half century, with approximately 390 million infections in 2010, partly due to warming temperatures and the associated spread of the mosquito species that carry and spread the disease.