epidemiology
Estimated 3-5 million cholera cases and 100 000-120 000 deaths occur each year due to cholera (1)
- the number of cholera cases reported to WHO continues to rise. In 2011 alone, a total of 589 854 cases were notified from 58 countries, including 7816 deaths (1)
- in endemic areas
- the incidence of cholera is highest in children
- the incidence tends to decrease with age due to acquired immunity
- in non-endemic areas cholera prevalence is not age dependent - this reflects that most of the population have no immunity to the bacterium (2)
The following environmental factors results in an increase in cholera infection:
- increase in phytoplankton and zooplankton (which V choleraeis often associated with) caused by changes in surface water temperature and terrestrial nutrient discharge
- during floods (compared with non-flood periods)
- in natural disasters such as cyclones and earthquakes (2)
Due to improvements in sanitation, public health and medical knowledge, cholera is now rare in Europe. The last indigenous case of cholera in England and Wales was reported in 1893
- occasional imported cases occur, but the risk of an outbreak is very small in countries with modern sanitation and water supplies, and high standards of food hygiene
- in England, Wales and Northern Ireland 126 laboratory notifications of cholera from 1990 through to 2001 were reported
- of these, 64% were imported from the Indian sub-continent. Cholera due to the classical biotype of V. cholerae was endemic in the Ganges Delta of West Bengal and Bangladesh during the last two centuries and caused epidemics and global pandemics (3)
PHE state (4):
- cases in the UK occur in travellers returning from endemic areas (Africa, Asia, Central and South America, Caribbean)
- an average of 16 cases of cholera caused by Vibrio cholera O1 and O139 have been reported in England and Wales between 2004 and 2012
- no confirmed cases have been reported from Northern Ireland since 2004
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