Number of reported cholera cases
In 2012, a total of 48 countries from all continents reported 245 393 cases of cholera to WHO, of which 48% were reported from Africa and 49% from the Americas where a large outbreak that started in Haiti at the end of October 2010 and also affected the Dominican Republic. Globally, however, the true number of cholera cases is known to be much higher. Cases of cholera officially reported to WHO do not account for the estimated 500 000–700 000 cases labelled as acute watery diarrhoea. These cases occur in vast areas of Central and South-East Asia, and in some African countries, leading to great underestimation of the global burden of this disease. The discrepancy results from underreporting and other limitations of surveillance systems, including inconsistencies in case definitions and the lack of a standard vocabulary. Some countries report only laboratory-confirmed cases, although many more cases are consistent with WHO’s standard case definition of cholera.
In 2012, 48% of cases were reported from Africa whereas between 2001–2009, 93% to 98% of total cases worldwide were reported from that continent. It is the third year in a row that such a low proportion of cases has been reported from the African continent. This was already the case in the early nineties shortly after the 7th pandemic had reached the south American continent in 1991. After several years of steady increase (since 2005), the number of cholera cases reported to WHO, as well as the number of countries which reported cases showed an important decrease in 2012. Despite this decrease, many people still die of the disease notably in Sub-Saharan Africa, Asia and in Hispaniola, clearly showing that cholera remains a significant public health problem.