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WHO Report on Global Surveillance of Epidemic-prone Infectious Diseases - Cholera: Previous page | 1,2,3,4,5,6

Description of the data

  :: Table of contents
  1. Background of the disease
  2. Description of the data
  3. Trends
  4. Conclusions
  5. References & links
  6. Tables

Cholera was the first disease for which modern public health surveillance and reporting was carried out in an organized way. It is one of the three diseases currently reportable under the International Health Regulations (IHR) of 1969. According to those regulations, national health administrations should report the first cases of cholera on their territory to WHO within 24 hours of their being informed. This applies to both indigenous cases of cholera as well as imported cases. Cholera cases and deaths reported to WHO during the week are published in the Weekly Epidemiological Record (WER). In addition the WER provides annual summary tables of cholera cases and deaths as well as short notes on outbreaks of cholera. Reports of important outbreaks also appear on the WHO web pages under Disease Outbreak News as listed in the references. Data presented in this chapter, include reports of cholera dating back to 1949 for Asia when cases were first reported in that continent. For Africa the data began in 1970 with the acceptance of the International Health Regulations. This covers a relatively long period of time and allows recent trends in cholera incidence and mortality to be interpreted in light of past experience. The annual number of reported cases of cholera for each country is presented at the end of the chapter.

Strengths and weaknesses of the data

The data presented in this report have been obtained from official reports to WHO. As is the case with other diseases under the IHR, notification of cases is mandatory, but reporting is not complete. Countries are reluctant to report cholera for political and economic reasons. They fear loss of tourism and trade, and travel restrictions. This results in considerable delays in reporting, and in substantial underreporting of cases. For a few countries, there have been no cases of cholera reported for many years, despite references in the literature to many cholera cases in those countries. Often cholera is reported to WHO as acute watery diarrhoea, in order to avoid the perceived negative consequences of reporting cholera, while at the same time acknowledging a severe epidemic of diarrhoeal disease.

Poorly functioning surveillance systems in some parts of the world (particularly in Africa) contribute to the underreporting of cases. Thus, not only are there many more cases of cholera than the number reported, but also the completeness of the reporting varies considerably by country.

WHO Report on Global Surveillance of Epidemic-prone Infectious Diseases - Cholera: 1,2,3,4,5,6 | Next page

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