Solar Disinfection of Drinking Water and Oral Rehydration Solutions
Disinfection Guidelines for Household Application in Developing
Countries > Oral Rehydration Therapy: Causes, Transmission, and Control
of Childhood Diarrhoea
Oral Rehydration Therapy: The Revolution for Children
Oral Rehydration Therapy: The Four Simple Technologies
Global Rehydration Therapy: Global Diarrhoeal Diseases Control Programmes
Oral Rehydration Therapy: Causes, Transmission, and Control of Childhood Diarrhoea
Oral Rehydration Solutions: The Practical Issues
Oral Rehydration Solutions: Domestic Formulations
Oral Rehydration Solutions: Disinfection by Boiling
Solar Energy: Fundamental Considerations
Solar Energy: From Sun to Earth
Solar Energy: World Distribution
Solar Energy: A Competitor
Solar Energy: Some Practical Hints
Solar Disinfection Studies: Drinking Water
Solar Disinfection Studies: Oral Rehydration Solutions
Appendix: Source of Information on Diarrhoeal Diseases
Oral Rehydration Therapy
Causes, Transmission, and Control of Childhood Diarrhoea
Until about ten years ago, only a fraction of the microbial causes of
human diarrhoeal diseases were known as no pathogenic bacteria and
viruses could be isolated from the large majority of patients. So far,
about 25 pathogenic bacteria, viruses, and parasites have been
identified as causes of diarrhoea.
The well known microbial agents of universal importance that invade
the intestine and cause acute diarrhoea through a variety of
mechanisms are Shigellae, Salmonellae, V. cholerae, and certain
strains of E. coli (ETEC, EIEC, and EPEC). The two other unicellular
micro- organisms (protozoa) of world-wide distribution causing both
acute and chronic diarrhoea, especially among children, are Giardia
lamblia and Entamoeba histolytica.
Other conditions associated with diarrhoea include infections
occurring in organs other than the intestine (e.g. measles, malaria,
and pneumonia), as well as malnutrition and food intolerance.
In recent years, five groups of enteric viruses involved in childhood
diarrhoea have been recognized through electron microscopy and
successful stool cultures. These are rotaviruses, enteric
adenoviruses, asroviruses, coronaviruses, and Norwalk
viruses. In addition, a number of other infectious agents of
limited or unknown importance in diarrhoeal diseases have been
identified in diarrhoeal stools. Among these are Campilobacter
jeujeni and Yersinia enterocolitica.
In 1982, Dr. I. de Zoysa and associates of the Ross Institute in
London published a wall chart entitled A Guide to the Most Common
Enteric Pathogens which provides practical information regarding
each of the potential causative agents of diarrhoeal diseases.
Little information is available about the world-wide distribution of
some of the newly identified diarrhoeal agents, particularly among
children in developing countries, primarily because of the complexity
of the diagnostic techniques. Fortunately, diagnosis of rotavirus
infection can now be made by means of a simple and rapid procedure
recently developed in Sweden based on assaying the antibodies in
stools (enzyme-linked immuno-absorbent assay -- ELISA).
Practically all of the more common childhood diarrhoeal diseases
caused by pathogenic bacteria and viruses are transmitted via the faecal-oral route. The pathogens discharged in the faeces of an infected
person may enter the body of another susceptible person through the
mouth. This may occur among children ingesting food or water contaminated
with human excreta.
Direct transmission among persons in close contact is also possible.
Such transmission could occur via unclean hands, or through
contaminated objects such as bed linen, kitchen utensils, and
tableware. Flies and cockroaches play a role as vectors of the
infectious agents of faecal origin.
During diarrhoeal episodes, the body rapidly loses fluids together
with some electrolytes that are discharged with the stools. The
essential electrolytes lost are sodium (Na+), potassium
(K+), chloride (Cl-), and bicarbonate
(HCO3-). At the same time, the intestine may
lose its capacity to absorb fluids and electrolytes taken by mouth. In
mild cases, where intestinal absorption is not impaired, any fluid
given orally might prevent dehydration. About 10 percent of diarrhoea
episodes result in dehydration due to the excessive loss of fluids and
electrolytes. Infants and young children are much more susceptible to
dehydration and its consequences than adults.
It has been demonstrated that ORT involving the oral administration
of glucose-electrolyte solutions can effectively restore the
intestinal fluid losses, thereby counteracting dehydration in the
large majority of cases. This is based on the fact that glucose
enhances the intestinal absorption of water and sodium in diarrhoea
Obviously then, ORT constitutes a short-term measure that can and must
be adopted on a global scale to enable prompt treatment of childhood
The four major strategies for controlling the transmission of the
common diarrhoeal diseases are: (a) personal and domestic cleanliness;
(b) hygienic food preparation and storage; (c) clean and plentiful
water supply; and (d) sanitary excreta and refuse disposal.
An essential long-term objective of national diarrhoeal disease
control programmes should therefore be based primarily on achieving an
improvement in community water supplies and in sanitation facilities
and practices. Much can be accomplished through training and health