Global epidemics and impact of cholera

Global epidemics

Man-made and natural disasters can intensify the risk of epidemics considerably, as can conditions in crowded refugee camps. Explosive outbreaks with high case-fatality rates are often the result. For example, in the aftermath of the Rwanda crisis in 1994, outbreaks of cholera caused at least 48 000 cases and 23 800 deaths within one month in the refugee camps in Goma, the Congo. Although rarely so deadly, outbreaks continue to be of major public health concern, causing considerable socioeconomic disruption as well as loss of life. In 2001 alone, WHO and its partners in the Global Outbreak Alert and Response Network participated in the verification of 41 cholera outbreaks in 28 countries.

Throughout history, populations all over the world have sporadically been affected by devastating outbreaks of cholera. Records from Hippocrates (460-377 BC) and Galen (129-216 AD) already described an illness that might well have been cholera, and numerous hints indicate that a cholera-like malady was also known in the plains of the Ganges River since antiquity.

Modern knowledge about cholera, however, dates only from the beginning of the 19th century when researchers began to make progress towards a better understanding of the causes of the disease and its appropriate treatment. The 1st pandemic, or global epidemic, started in 1817 from its endemic area in South-East Asia and subsequently spread to other parts of the world. The 1st and subsequent pandemics inflicted a heavy toll, spreading all over the world before receding.

In 1961, the 7th cholera pandemic wave began in Indonesia and spread rapidly to other countries in Asia, Europe, Africa and finally in 1991 to Latin America, which had been free of cholera for more than one century. The disease spread rapidly in Latin America, causing nearly 400 000 reported cases and over 4000 deaths in 16 countries of the Americas that year.

In 1992, a new serogroup – a genetic derivative of the EI Tor biotype – emerged in Bangladesh and caused an extensive epidemic. Designated V. cholerae 0139 Bengal, the new serogroup has now been detected in 11 countries and likewise warrants close surveillance. While no evidence is available to gauge the significance of these developments, the possibility of a new pandemic cannot be excluded. EI Tor, for example, was originally isolated as an avirulent strain in 1905 and subsequently acquired sufficient virulence to cause the current pandemic.

Economic and social impact

In addition to human suffering caused by cholera, cholera outbreaks cause panic, disrupt the social and economic structure and can impede development in the affected communities. Unjustified panic-induced reactions by other countries include curtailing or restricting travel from countries where a cholera outbreak is occurring, or import restrictions on certain foods. For example, the cholera outbreak in Peru in 1991 cost the country US$ 770 million due to food trade embargoes and adverse effects on tourism.

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