EPIDEMIOLOGY: In the past 200 years, there have been 8 main cholera pandemics, with the disease being most common in tropical and subtropical areas. Most of the cases are in the Indian subcontinent and Africa (in 2002 the WHO estimated that 97% of the cholera cases were in Africa). There are several million cases of cholera each year and in endemic areas, these tend to be most common in children aged 2-9 and in women who are of child-bearing age. Epidemics in endemic areas tend to occur during the hot season.