Cholera is mainly transmitted through contaminated water and food and is closely linked to inadequate environmental management. The absence or shortage of safe water and sufficient sanitation combined with a generally poor environmental status are the main causes of spread of the disease. Since 2005, the re-emergence of cholera has been noted in parallel with the ever-increasing size of vulnerable populations living in unsanitary conditions. Cholera remains a global threat to public health and one of the key indicators of social development. While the disease is no longer an issue in countries where minimum hygiene standards are met, it remains a threat in almost every developing country. The number of cholera cases reported to WHO during 2006 rose dramatically, reaching the level of the late 1990s. A total of 236 896 cases were notified from 52 countries, including 6311 deaths, an overall increase of 79% compared with the number of cases reported in 2005. This increased number of cases is the result of several major outbreaks that occurred in countries where cases have not been reported for several years. It is estimated that only a small proportion of cases - less than 10% - are reported to WHO. The true burden of disease is therefore grossly underestimated.
