Most common forms of diarrhea occur when a bacteria or virus proliferates in the gut. This infection leads to dehydration through excess fluid loss from the gut. Diarrheal disease is one of the leading causes of death of children under five and is particularly acute among infants. Diseases such as cholera when untreated can lead to death in more than one out of four cases.
Mechanism of Action
After digestion and nutrient absorption occurs in the small intestine, the large intestine generally absorbs excess water from the waste. In cases of diarrhea, the normal absorption or secretion of water does not function properly leading to the loss of water in stool. Oral rehydration solutions (ORS) contain both salt and glucose to take advantage of the coupled nature of sodium and glucose transport from the gut into the body. Even when the body is not absorbing water actively, the water will follow the osmotic gradient created by the salt and sugar from the gut into the rest of the body, thus rehydrating the child.
Oral rehydration solutions may also contain other electrolytes which have been lost along with the high fluid loss. WHO recommendations include potassium and citrate. Current recommendations add zinc therapy as it is often undersupplied in low nutrient diets and it helps the immune system. Zinc supplementation decreases diarrheal rates as well as other infection rates in children who are undernourished. Finally, it is important that oral rehydration solution be created with clean water to avoid adding to the current infection with new pathogens in unclean water.
Current Use in High-Resource Settings
In high-resource settings, oral rehydration therapy is available over the counter. In medical settings, intravenous rehydration therapy is often done as it is faster and perceived to be more advanced.
Application in Low-Resource Settings
Approximately 20% of diarrheal cases are treated with ORS in low-resource settings, saving an estimated 500,000 lives annually. UNICEF currently distributes 1 million packets every 3.5 days. Large scale dissemination programs have had great successes. It is important to combine distribution with an understanding of their importance by all practitioners. From 1982-88, a national diarrheal control program in Egypt reduced infant diarrheal deaths by 82% using ORS. In Bangladesh, BRAC trained 13 million mothers to make and administer ORS at home. Today, ORS is used in approximately 80% of Bangladeshi childhood diarrhea cases. WHO has introduced a revised, low-osmolarity formulation.