Cholera is a bacterial infection transmitted through ingesting contaminated water or food caused by Vibrio cholera bacteria. Cholera is an acute diarrhoeal disease that can be fatal within hours if left untreated. The mortality rate is between 25 and 50 percent for untreated cases. Every year, there are around four million cases, with up to 143,000 related deaths. Climate change and other factors have made Cholera cases increase by 13 percent and deaths by 71 percent in 2023 compared to 2022.
The worst-affected areas remain in African countries where the infrastructure for water and healthcare is fragile. Since around October 2023, Zambia has been experiencing a deadly Cholera outbreak, exacerbated by the higher-than-usual rainfall, with at least 20,000 positive cases and over 700 fatalities recorded. More recently, Nigeria’s Borno state reported 888 suspected Cholera cases, exacerbated by flooding that displaced nearly two million people as of October 2024.
However, with extreme weather events becoming more frequent, the risk of outbreaks rises even in developed countries. Hurricane Helene in the US damaged sewage systems, wastewater treatment plants and water pipes, leaving thousands of residents without access to a clean water supply. Authorities issued more than 160 boil water advisories in affected areas to mitigate the risk of drinking contaminated water. While no cholera outbreaks were connected to this latest extreme weather event, the disruptions Hurricane Helene caused underscore the public health risks as these become more frequent.
Cholera outbreaks also affect travel. Authorities in Egypt, Madagascar, Mayotte and Reunion have imposed Cholera screening measures on travellers at their territory’s entry points in 2024. Madagascar bans passenger ships from Comoros entirely to prevent the entry of cholera.
