2016–2021 Yemen cholera outbreak in the context of Yemeni Civil War (2015–present)

The 2010s Haiti cholera outbreak was the first modern large-scale outbreak of cholera—a disease once considered under control largely due to the invention of modern sanitation. The disease was reintroduced to Haiti in October 2010, not long after the disastrous earthquake earlier that year, and since then cholera has spread across the country and become endemic, causing high levels of both morbidity and mortality. Nearly 800,000 Haitians have been infected by cholera, and more than 9,000 have died, according to the United Nations (UN). Following the outbreak's conclusion in February 2019, cholera transmission in Haiti is largely the subject of eradication efforts including WASH (water, sanitation, and hygiene), education, oral vaccination, and climate variability. Early efforts were made to cover up the source of the epidemic, but thanks largely to the investigations of journalist Jonathan M. Katz and epidemiologist Renaud Piarroux, it is widely believed to be the result of contamination by infected United Nations peacekeepers deployed from Nepal. In terms of total infections, the outbreak has since been surpassed by the war-fueled 2016–2021 Yemen cholera outbreak, although the Haiti outbreak is still one of the most deadly modern outbreaks. After a three-year hiatus, new cholera cases reappeared in October 2022.

Seven cholera pandemics have occurred in the past 200 years, with the first pandemic originating in India in 1817. The seventh cholera pandemic is officially a current pandemic and has been ongoing since 1961, according to a World Health Organization factsheet in March 2022. Additionally, there have been many documented major local cholera outbreaks, such as a 1991–1994 outbreak in South America and, more recently, the 2016–2021 Yemen cholera outbreak.

Although much is known about the mechanisms behind the spread of cholera, this has not led to a full understanding of what makes cholera outbreaks happen in some places and not others. Lack of treatment of human feces and lack of treatment of drinking water greatly facilitate its spread. Bodies of water have been found to serve as a reservoir, and seafood shipped long distances can spread the disease.