Diarrhea is one of the leading causes of childhood mortality worldwide — dehydration assessment is the critical clinical priority, followed by identifying the causative organism.
Children are at higher risk of rapid dehydration than adults due to their smaller body weight and higher surface-area-to-volume ratio. A toddler with frequent watery stools can lose dangerous amounts of fluid within hours. The WHO dehydration assessment classifies severity by clinical signs and guides management: oral rehydration solution (ORS) for mild-moderate, IV fluids for severe.
Rotavirus
Most common cause of severe diarrhea under 5. Watery diarrhea, vomiting, fever for 3–8 days. Largely preventable by vaccination.
Greasy, pale, foul-smelling diarrhea with bloating and failure to thrive. Common in daycare settings and after travel. Stool antigen test.
Campylobacter / Salmonella
Bloody or watery diarrhea with fever. Typically after undercooked poultry. Self-limiting in 5–7 days; antibiotics only in severe cases.
Heavy pinworm infections can cause loose stools alongside anal itching. Often overlooked cause in children.
C. difficile (post-antibiotic)
Watery diarrhea after antibiotic use. Stool toxin assay diagnostic. Less common in children than adults but does occur.
Diarrhea with malnutrition and growth failure in children with heavy Ascaris burden in endemic areas.
Signs of mild-moderate dehydration: dry mouth, less active than usual, no tears when crying, fewer wet nappies (less than 4 per day in infants, urination less than every 8 hours in older children). Signs of severe dehydration: sunken eyes, sunken fontanelle (infants), mottled or cold skin, very drowsy or unconscious. Severe dehydration requires immediate emergency care.
Yes. ORS (like Dioralyte or WHO oral rehydration salts) is the most effective treatment for mild-moderate diarrhea dehydration in children. It replaces water and electrolytes precisely. Fruit juice, cordial, and carbonated drinks are NOT substitutes — their high sugar content can worsen diarrhea. Breastfeeding should be continued throughout.
Yes, giardiasis is the most common parasitic cause of diarrhea in school-age children in temperate countries. It spreads easily through the faecal-oral route in group settings (sharing toys, water play). A child with giardiasis should be excluded from daycare or school until 48 hours after their first normal stool, and treated with mebendazole or tinidazole.
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