Cholera
Seven cholera pandemics have happened in the past 200 years.  The latest started in Indonesia in 1961.  There have also been many serious outbreaks.  The worst outbreak in recent history happened in Haiti after the earthquake there in 2010.  Between October 2010 and August 2015, more than 700,000 Haitians got cholera, and over 9,000 died.  The outbreak was caused by a United Nations base where Nepalese soldiers were living.  The soldiers would dump human waste into the Artibonite River, which many Haitians used for drinking, cooking, and bathing.