Seasonal blooms: what causes periodic coastal cholera proliferation?

Flooding in Bangladesh - a sure risk of the spread of endemic cholera

Cholera cases total between 3-5 million each year with 100,000-120,000 deaths. It is endemic in Asia and Africa. It causes devastating outbreaks and global pandemics. It is said to have originated in the Bay of Bengal.

The two most recent outbreaks of this gastro-intestinal disease are in Haiti and the Congo River. As of 10 July 2011 388,958 cases had been reported in Haiti, with 5,899 deaths. On 20 July 2011 the World Health Organisation reported 3,896 cases and 256 deaths on the banks of the Congo River in the Democratic Republic of Congo. From 14 to 20 July a total of 181 cases and six deaths were reported in the neighboring Republic of Congo.

Cholera is entirely preventable with comprehensive provision of hygiene, sanitation and drinking water. There has not been an outbreak of cholera in London since such infrastructure was built in the mid-19th century.