Persistent Diarrhoea
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Direct answer
Persistent diarrhoea is diarrhoea that lasts 14 days or more, and it is a major contributor to malnutrition in young children. It usually follows an acute enteric infection that damages the intestinal lining, and the central principle of management is continued feeding rather than fasting. Zinc is given for 10 to 14 days along with oral rehydration, and stool and nutritional evaluation are needed when the diarrhoea does not settle.
What you must remember
- Definition: diarrhoea lasting 14 days or more, which separates it from acute diarrhoea that settles within 14 days.
- Mechanism: the infection damages the mucosa, causing secondary disaccharidase deficiency and malabsorption that keep the illness going.
- Pathogens: enteroaggregative E. coli, Giardia, Cryptosporidium, Shigella, Campylobacter and Entamoeba histolytica are important causes, with CMV and HIV considered in immunocompromised children.
- Non-infectious causes: cow's milk protein intolerance, coeliac disease, cystic fibrosis and immunodeficiency should be considered when no infection is confirmed.
- Feeding: continue breastfeeding and the usual diet, with extra fluids, and never withhold food to rest the bowel.
- Zinc: give 10 mg daily below six months and 20 mg daily above six months, for 10 to 14 days, whatever the stool frequency.
- Lactose: a lactose-reduced formula is used only when secondary lactose intolerance is suspected, not as a routine change.
Acute and persistent diarrhoea compared
A 9-month-old has had watery diarrhoea for three weeks after a gastroenteritis episode, and his weight has fallen. The comparison below shows how persistence changes the approach.
| Feature | Acute diarrhoea | Persistent diarrhoea |
|---|---|---|
| Duration | Under 14 days | 14 days or more |
| Typical cause | Mostly viral, such as rotavirus or norovirus | Enteric infection with malabsorption, or a non-infectious cause |
| Stool examination | Often not needed | Stool microscopy and culture |
| Main treatment | Oral rehydration and zinc | Nutrition, zinc and treatment of any proven cause |
| Antibiotics | Only for specific indications | Only for a proven pathogen |
| Dehydration risk | High in the early phase | Monitored by weight and electrolytes |
| Weight | Usually maintained | Often falling, so growth is charted at each visit |
The duration threshold changes the work-up, but it does not change the basic rule of continued feeding. A child with persistent diarrhoea needs a search for both infection and malabsorption, and the weight chart is the simplest guide to the response.
Where the exam tries to catch you
Most lost marks here come from stopping feeds or giving antibiotics by habit.
- Trap: stopping milk feeds to let the bowel rest Correct: continued feeding is the rule, and a lactose-reduced formula is used only when secondary lactose intolerance is suspected.
- Trap: giving antibiotics for every case Correct: antibiotics are reserved for a proven pathogen, since most persistent diarrhoea is managed with nutrition and zinc.
- Trap: stopping zinc as soon as the stools normalise Correct: zinc is given for the full 10 to 14 days regardless of stool frequency.
Frequently asked questions
What is the definition of persistent diarrhoea in children?
Persistent diarrhoea is defined as diarrhoea lasting 14 days or more, which distinguishes it from acute diarrhoea that settles within 14 days. The episode usually begins as an acute infection and continues because the intestinal lining has not recovered.
What is the zinc dose in persistent diarrhoea?
Zinc in persistent diarrhoea is given at 10 mg daily for infants under six months and 20 mg daily for older children. It is continued for 10 to 14 days in full, even after the stools have become normal.
Why should feeding continue in persistent diarrhoea?
Feeding should continue in persistent diarrhoea because fasting worsens malnutrition and slows the recovery of the intestinal lining. Breastfeeding and the usual diet are continued with extra fluids, and a lactose-reduced formula is used only if secondary lactose intolerance is suspected.
Which investigations are needed for persistent diarrhoea?
Stool microscopy and culture, serum electrolytes, blood counts and serum albumin are the basic investigations in persistent diarrhoea. Tissue transglutaminase antibody is added when gluten is in the diet, and a sweat test is considered when cystic fibrosis is suspected.