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

Trends

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

Incidence

  • Cholera is a major public health problem that is becoming increasingly important as the number of countries affected continues to increase.
  • New major outbreaks of cholera are continuing to occur, especially in the wake of climate changes.
  • During 1998, there was a dramatic increase in the number of cholera cases worldwide compared to 1997, with the total number of cases almost doubling.
  • Africa reported 211 748 cases in 1998, the highest number of cases ever reported and accounted for 72% of the global total. There had been a sudden increase of cholera at the end of 1997 in the Horn of Africa, and this continued throughout 1998 and spread to many other countries. During the year, major outbreaks occurred in the Democratic Republic of the Congo, Kenya, Mozambique, Uganda and the United Republic of Tanzania. There was a large increase in reported cholera cases in west Africa. Eleven countries reported outbreaks of cholera in September 1998.
  • The Americas reported an upturn in cholera cases from 17 760 in 1997 to 57 106 in 1998. This reverses the downward trend in the region. The increase affected Peru primarily, as well as Ecuador, Guatemala and Nicaragua. This recrudescence is most probably related to the continuing effects of major disasters caused by El Nino and Hurricane Mitch.
  • The number of cases reported in Asia continued the rise that began in 1997. There were more than twice as many cases in 1998 compared to 1997, with large increases in reported cases in Afghanistan, India, Cambodia, Malaysia, Nepal and Sri Lanka.


Fig. 4.1 Cholera, reported number of cases and case fatality rates, 1950-1998

Fig. 4.1 Cholera, reported number of cases and case fatality rates, 1950-1998

Deaths

  • Figs. 4.1 and 4.2 present the annual number of reported cases of cholera from each continent since 1950 during the sixth pandemic. Case fatality rates were very high at that time and as many as 50-70% of cases died. With the replacement of classical cholera with El Tor, a less virulent strain, case fatality rates reduced dramatically during the 1960s. They have been further reduced, through better treatment and in particular more widely available oral rehydration therapy which was introduced during the early 1970s but which became widely available in many parts of the world during the 1980s.
  • For the majority of cases, treatment with oral rehydration is sufficient. However, when either safe water or oral rehydration salts are not available, case fatality rates can be very high. A case fatality rate of 25-50% was estimated in refugee camps in Goma amongst those who were not treated. Where good treatment is readily accessible, the case fatality rate is less than 1%. Nowadays there are still large differences in case fatality rates from outbreak to outbreak. These differences are mainly due to differences in access to appropriate treatment and not because of alterations in virulence.
  • In Africa, there has been a marked decline in case fatality rates since 1970, however Africa continues to have the highest reported case fatality rates (close to 5% in 1998) compared to the rest of the world.
  • In Asia, reported case fatality rates have declined markedly since 1970, with a case fatality rate under 1% for 1998.
  • Average case fatality rates for Europe and the Americas continue to hover around 1%.
  • Since the case fatality rates are so different in different parts of the world, the global case fatality rates reflect only partly the trends in each region, as the global rates are also affected by the global distribution of cases.

Fig. 4.2 Cholera, reported number of cases and case fatality rates, per continent

Fig. 4.2 Cholera, reported number of cases and case fatality rates, per continent

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

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