Epidemiology

In 2004, there were 5000 child deaths per day from diarrhea (WHO, 2005). However, in 2009 diarrheal child deaths had been reduced to about 4100 per day (WHO 2009). Recently, this number has again found to be lower, at about 2,200 children per day (Lui et al., 2012).  Globally, it is estimated that there are about 1.7 billion cases of diarrheal disease yearly (WHO, 2013). While the mortality rate from diarrhea has decreased slightly in recent years, the incidence has remained relatively stable (Boschi-Pinto, 2009). This implies that while treatment interventions such as oral rehydration salts (ORS) and other therapies have been successful, preventative health interventions are not being implemented with the same degree of success.

Extent and Scope

 The incidence of diarrheal disease is two to three times higher in developing countries (WHO, 2005).  Diarrhea is a challenge predominantly in low-income countries that are overcrowded and lack access to safe drinking water (WHO, 2005). In 2013, it was reported that nearly 780 million individuals lack access to clean drinking water (WHO, 2013). Currently, 88 percent of diarrheal deaths worldwide can be attributed to unsafe water and inadequate hygiene and sanitation practices (UNICEF/WHO, 2009).  

Transmission

The primary routes of transmission for diarrheal diseases are fecal-oral, person-to-person, and direct contact with pathogen-infected feces. Fecal-oral transmission is the ingestion of water or food contaminated with infected feces. Person-to-person transmission may occur when one prepares food or handles children with unclean hands. Direct contact with infected feces usually occurs when children play in an area that is contaminated with feces (WHO, 2005).



Infectious agents linked with diarrhea include bacterial, viral, and parasitic organisms.  Cryptosporidia, rotavirus, and cholera are the pathogens primarily associated with acute watery diarrhea (Naficy, 2000). Pathogens that cause dysentery or bloody diarrhea include astrovirus, enterotoxigenic escherichia coli (ETEC), shigella and salmonella.  Though persistent diarrhea does not have a single microbial cause, E. coli and cryptosporidia are most often implicated (WHO/ UNICEF, 2008). 

Rotavirus is the most common cause of life-threatening diarrhea in children under 5 worldwide. The World Health Organization estimated that in 2004, rotavirus was responsible for 527,000 children deaths (Ahmed, 2009).  In that same year, six countries were responsible for more than half of the rotavirus deaths: India, Nigeria, the Democratic Republic of the Congo, Ethiopia, China, and Pakistan (Ahmed, 2009).  The UNICEF/WHO report on diarrhea found that of all hospital admissions caused by diarrhea, rotavirus was responsible for 40 percent of them (UNICEF/WHO, 2009).  

Pathology

Diarrhea is caused by pathogens that include bacteria, protozoa, and viruses. It kills by rapidly draining water and electrolytes out of the body. Morbidity and mortality increase when recurrent diarrhea is coupled with immune compromising conditions such as inadequate feeding, weaning, recent/current measles, malaria, and AIDS (UNICEF/WHO, 2004). The causes of diarrhea include infection, malnutrition, and contaminated food and water. Children with frequent bouts of diarrhea enter into a cycle of malnutrition, anemia, and decreased immune function. This results in severe loss of energy and protein which ultimately leads to death (UNICEF/WHO, 2004). 

There are three main types of diarrhea:

• acute watery diarrhea -lasts several hours or days, and includes cholera
• acute bloody diarrhea - also called dysentery
• persistent diarrhea - lasts 14 days or longer (WHO, 2013)

Signs and Symptoms          

Early warning signs of dehydration due to diarrhea are difficult to identify and often present little to no signs or symptoms (Boschi-Pinto, 2009).  The National Institute of Health (NIH) reports some of the signs and symptoms of dehydration due to diarrheal disease in children as:

• dry mouth and tongue
• no tears when crying
• no wet diapers for 3 hours or more
• sunken eyes or cheeks
• soft spots in the skull
• highfever
• listlessness or irritability 
• skin when pinched does not flatten back to normal right away (NIH, 2012)

Fig. 2: Dehydration in Children (Nursingcrib, 2011)

Depnding on the severity of the dehydration, it may be necessary to to refer the child to a health care provider or hospital to receive the appropriate treatment.  This is usually the case with persistent Diarrhea particularly where it is coupled with severe dehydration.

Health, Economic, and Social Impact

When researchers look at diarrhea from the perspective of morbidity, they find long-term effects that contribute not only to the impaired growth of a child with early diarrhea in their first two years, but also impaired fitness, cognitive function, and school performance between 6-12 years of age (Guerrant, 1999). Not all of these cases end in mortality. Therefore, the examination of non-fatal cases is essential to assess the true burden of illness in children with diarrheal disease.