It’s a serious risk, and it’s something the world could be smarter about. The worst pandemic in modern history was the Spanish flu of 1918, which killed tens of millions of people. Today, with how interconnected the world is, it would spread faster.
Bill Gates (2014)
The Cholera epidemic in Haiti in 2010/2011 (following a massive earthquake) killed with almost 7000 reported deaths the highest number of people in a single outbreak, followed by the Ebola outbreak in Liberia in 2014. The overall highest number of deaths are reported in Burkina Faso.
Overall most of the deaths were caused by Cholera outbreaks, a bacterial infection, that benefits from bad sanitation facilities.
Most of the reported epidemics happened in countries in Sub-Saharan Africa, The Democratic Republic of Congo is leading that list, followed by Nigeria, Niger, Uganda and Sudan. More than 67.000 out of the total 86.000 victims of epidemics were from Africa. The only non African country among the Top 10 is India, where the epidemics are mostly Japanese Encephalitis and Cholera.