According to the WHO, acute diarrhoea is defined by at least three liquid and/or soft stools per day for at least 14 days. When diarrhoea lasts longer than one month or becomes recurrent, it is called chronic diarrhoea. This distinction is important from the practical point of view for etiological reasons and also due to the underlying physiopathological mechanisms. Therefore, it appears difficult, even illogical, to treat all these diseases in a global manner. However, it should be noted that in practice, symptomatic treatment of diarrhoea is logically addressed to these different types of diarrhoea.
Acute diarrhoea represents one of the most common public health problems in the world. Fortunately, the outcome is, in most cases, spontaneously favourable in five days and only 5% to 10% of the patients need to be investigated. However, due to the abundance of lost water and electrolytes, acute diarrhoea can be life-threatening, particularly for the very old and very young, and especially in subjects at risk.
In developing countries, diarrhoeal diseases constitute one of the main causes of mortality and morbidity in children, and a major cause of malnutrition and growth retardation.
In its latest report, (UNICEF/WHO, Diarrhoea: Why children are still dying and what can be done, 2009), the WHO estimates the number of episodes that strike children worldwide below the age of 5 annually at 2.5 billion, which has remained stable for two decades. Mortality has decreased in the past 20 years, with 1.5 million deaths attributable to these diseases in 2004. Despite this improvement, in all countries together, diarrhoea remains the second cause of death in children below age five, right after pneumonia. Together, pneumonia and diarrhoea represent 40% of all deaths of young children. Approximately 80% of deaths attributable to diarrhoea occur during the first two years of life.
The aetiology of acute diarrhoea is mainly infectious
In developing countries, rotavirus, enterotoxigenic Escherichia coli (ETEC), Campylobacter jejuni, Shigella and Cryptosporidium are the major causes of infantile diarrhoea. Other causes may be locally important: Vibrio cholerae (in endemic regions and during epidemics); Salmonella other than typhi (in regions where treated food is widely used) and enteropathogenic E. coli (EPEC) (in newborns in the hospital). Mixed infections due to two or more enteropathogenic agents occur in 5 to 20% of cases observed in healthcare institutions.
In western countries, viral infections are the most common aetiology for illnesses presenting with diarrhoea.
Treatment must be based on the main characteristics of the disease and on understanding the underlying pathogenesis. The essential treatment principles are the following:
- Watery diarrhoea, regardless of its aetiology, requires replacement of lost fluids and electrolytes.
- Food should be continued, in all types of diarrhoea, and increased during convalescence so as to prevent any harmful effect on nutritional status. Breastfeeding is preferred in young children and especially in areas of hygienic risk (hydration, nutrition and immune protection).
- Antimicrobials and antiparasitics should not be routinely used; the majority of episodes of diarrhoea, including serious ones accompanied by fever, do not respond to such treatment.
The place of probiotics in the treatment of diarrhoeal disorders can be deduced by different approaches. The physiopathological approach is the one most often applied and documented. In fact, due to their mechanisms of action and their mainly digestive site of action, it is according to this approach that the use of probiotics has been evaluated and justified as a possible symptomatic and even etiological diarrhoea therapy.
Preclinical and clinical studies (studies of pharmacodynamics, efficacy and tolerance in healthy volunteers and in adult or paediatric patients) validating the benefit of the use of probiotics for the symptomatic treatment of diarrhoea, show a favourable efficacy/adverse effect ratio mainly in comparison to placebo.