Acute gastroenteritis consists of diarrheal disease of rapid onset, often with nausea, vomiting, fever, or abdominal pain. On an average, it occurs about 1.3-2.3 times per year between the ages of 0 and 5 years. Most episodes of acute gastroenteritis will resolve within 3 to 7 days.
Gastroenteritis in children is caused by viral, bacterial, and parasitic organisms, although the vast majority of cases are viral or bacterial in origin.
2. Viral gastroenteritis
All the viruses will produce watery diarrhea often accompanied by vomiting and fever, but usually not associated with blood or leukocytes in the stool or with prominent cramping.
Rotavirus is the predominant viral cause of dehydrating diarrhea.
Norwalk viruses are the major cause of large epidemics of acute nonbacterial gastroenteritis.Enteric adenovirus is the third most common organism isolated in infantile diarrhea.
3. Bacterial gastroenteritis
The bacterial diarrheas are caused by elaboration of toxin (enterotoxigenic pathogens) or by invasion and inflammation of the mucosa (invasive pathogens).
Secretory diarrheas are modulated through an enterotoxin, and the patient does not have fever or myalgias or tenesmus, or white or red blood cells in the stool. The diarrhea is watery, often is large in volume, and often associated with nausea and vomiting.
Invasive diarrheais caused by bacterial enteropathogens. Cramps and abdominal pain are prominent. The diarrhea consists of frequent passing of small amounts of stool within the mucus.
4. General approach tothe patient with gastroenteritis
Determining and managing the fluid losses, dehydration and electrolyte abnormalities is more important than ascertaining the specific microbiologic cause.
History should assess recent antibiotic use, underlying diseases, other illnesses in the family, travel, untreated water, raw shellfish, and foods eaten recently.
Mildly or moderately dehydrated children should receive oral rehydration therapy (ORT).
Replacement of stool losses (at 10 mL/kg for each stool) and of emesis (estimated volume) will require adding appropriate amounts of solution to the total.
Use of cola, fruit juice and sports beverages are not recommended and their electrolyte content is inappropriate, and they contain too much carbohydrate.
Prevention of dehydration
Children who have diarrhea, but not dehydrated, may be given glucose-electrolyte solution in addition to their regular diets to replace stool losses. The well-hydrated child should continue to consume an age-appropriate diet and drink more than the usual amounts of the normal fluids.
Severely dehydrated children who are in a state of shock must receive immediate and aggressive intravenous (IV) therapy. When the patient is stable, hydration may be continued orally.
When intravenous rehydration is required, it should begin with an isotonic solution. Severe dehydration clinically is associated with a loss of 10-12% of body weight in fluids and electrolytes (100 to 120 mL/kg). Therefore, this amount plus additional losses should be infused.
Infusion rates of up to 100 mL/min are appropriate in older children.
Subsequent maintenance fluids should be given orally. Oral fluids should be initiated as soon as the patient can drink. They should be given simultaneously with intravenous fluids until the total fluids administered have replenished the calculated deficit.
: The effectiveness of antimicrobial therapy is well established in shigellosis.
Shigella is the cause of bacterial dysentery and is the second most commonly identified bacterial pathogen in diarrhea between the ages of 6 months and 10 years.
It causes watery diarrhea with mucus and gross blood. Treatment consists of ceftriaxone or cefixime.
Children who have diarrhea and are not dehydrated should continue to be fed age-appropriate diets. Fatty foods and foods high in simple sugars, such as juices and soft drinks should be avoided. Well-tolerated foods include complex carbohydrates (rice, wheat, potatoes, bread, cereals), lean meats, yogurt, fruits, and vegetables.
Antidiarrheal compounds (eg, loperamide, diphenoxylate, bismuth compounds, Kaopectate) should not be used to treat acute diarrhea.
5. Laboratory examinations
The presence of blood in the stool, fever, or persistence of the diarrhea for more than 3 days may trigger a laboratory pursuit of an etiologic agent.
If erythrocytes and white blood cells are present, particularly in the setting of fever, a bacterial pathogen (Campylobacter, Yersinia, Salmonella,Shigella) should be suspected by microscopic stool examination. Many red blood cells in the absence of white blood cells suggests the presence of Entamoeba.
Stool culture should be reserved for individuals whose diarrhea has not responded to fluid and feeding and for those who have fever and the presence of leukocytes or red blood cells in the stool.