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Diarrhea Epidemiology

By Dr Ananya Mandal, MD

Diarrhea kills 1.8 million children under five in developing countries. This figure, however, is an improvement from 4.5 million deaths in last 20 years.

Annual incidence of diarrheal disease episodes in children less than five years old in developing countries thus stands at 2 billion diarrheal episodes globally with a median incidence rate of 3.2 episodes per child.

In community based studies the ratio between male children under five to female children under five suffering from acute diarrhea in 1.2 and 1.4 respectively. It is however important to note that some countries (e.g., in South Asia) have greater care seeking for boys than girls.

The identified microbes from diarrhea patients in community studies and health care facility studies respectively include:-

Percentage of identification of selected enteropathogens from children with diarrhea in 61 community-based studies

Enteropathogen Percentage %
Enterotoxigenic Escherichia coli 14
Enteropathogenic Escherichia coli 9
Rotavirus 8
Campylobacter 8
Cryptosporidium 6
Shigella 5

Percentage identification of selected enteropathogens from children with diarrhea in 107 health facility-based studies

Enteropathogen Percentage %
Rotavirus 25
Enteropathogenic Escherichia coli 16
Enterotoxigenic Escherichia coli 10
Shigella 6
Campylobacter 5
Salmonella 4

Apart from bacterial causes there are several viruses and parasites that may cause diarrheal diseases. Diarrheal diseases in 56.67 % of cases have a viral cause.

In the United States for example some agents are more important than others. A comparison of the relative importance of these viruses and bacteria in causing diarrheal diseases show:-

Etiologic agent Developing country U.S.
Rotavirus Important Very Important
Noroviruses Probably Important Important
Enteric adenoviruses Minor Probably Important

Comparison of bacterial etiologic agents of diarrhea in developing countries and the United States include:-

Etiologic agent Developing country U.S.
Enterotoxigenic Escherichia coli Very Important Minor
Campylobacter Important Important
Shigella Important Minor
Salmonella Variable Important
Enterohem. Escherichia coli Minor Important

Comparison of parasitic etiologic agents of diarrhea in developing countries and the United States show:-

Etiologic agent Developing country U.S.
Cryptosporidium Important Minor
Giardia Minor Minor
Strongyloides Minor Minor
Entamoeba histolytica Minor Minor

Seasonal variations are common. While bacterial diarrhea episodes are most common during summer and rains the viral diarrhoeas peak during winters. Transmission of diarrheal infections however is present throughout the year.

Viral diarrhoeas are more common in Europe, America and Asia and the Russia Federation. Of these the more important ones include rotaviruses and adenoviruses.

Diarrhea incidence rates by WHO region for 2010
  Age
Episodes of Diarrhea per child year (Uncertainty bounds)
Region 0-5 months 6-11 months 12-23 months 24-59 months 0-59 months
Africa 3.4 (2.1, 5.6) 5.1 (3.4, 8.1) 4.2 (2.7, 6.4) 2.7 (1.7, 4.2) 3.3 (2.2, 5.1)
Americas 4.1 (2.9, 5.2) 6.2 (4.7, 7.5) 5.0 (3.9, 5.8) 3.2 (2.3, 4.0) 4.0 (3.1, 4.7)
Eastern Mediterranean 3.1 (1.5, 5.2) 4.7 (2.4, 7.0) 3.8 (1.9, 5.4) 2.4 (1.3, 3.6) 3.0 (1.6, 4.4)
Europe 4.1 (3.0, 5.3) 6.3 (4.8, 7.6) 5.1 (3.9, 5.9) 3.2 (2.3, 4.1) 4.0 (3.1, 4.7)
South East Asian 2.4 (1.4, 4.0) 3.7 (2.2, 5.6) 3.0 (1.8, 4.3) 1.9 (1.2, 2.6) 2.4 (1.5, 3.3)
Western Pacific 2.3 (1.3, 3.1) 3.5 (2.0, 4.4) 2.9 (1.6, 3.3) 1.8 (1.1, 2.2) 2.3 (1.3, 2.6)
Global 2.9 (2.1, 4.3) 4.5 (3.4, 5.7) 3.6 (2.8, 4.4) 2.3 (1.8, 2.8) 2.9 (2.3, 3.4)

According to the World Health Organization between 1990 to 2010 while diarrhea incidence has declined from an estimated 3.4 episodes/child year in1990 to 2.9 episodes/child year in 2010, the highest burden of disease has remained consistent with respect to age.

The incidence is highest among children under 5 years of age living in low- and middle-income countries.

Reviewed by , BA Hons (Cantab)

Further Reading

Last Updated: Mar 24, 2013

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