Diarrhoea is an increased volume or frequency of stool, which has a liquid consistency (enough to fit in a container)
WHO defines diarrhoea as;
- 3 or more loose liquid stools per day, and/or
- Stools that are more frequent than what is normal for the individual, and/or
- Stool weight greater than 200g/d or 10ml/kg/d in infants
It has several causes and is the second leading cause of death in children < 5 years old.
Dysentery is stool that is small in volume, bloody, mucoid, and associated with abdominal pain or toxic appearance.
Normal stool frequency in young children
| Age group | Minimal | Maximal |
|---|---|---|
| Infant breast-fed | 1 every 10 – 14 days | 10 per day |
| Infant/toddler (3 years) | 1 every 2 days | 3 – 4 per day |
| Older children | 3 per week | 3 per day |
Timeline of diarrhoea
| Classification | Timeline | Common causes |
|---|---|---|
| Acute diarrhoea | < 2 weeks | Gastroenteritis, diverticulitis, antibiotic therapy, constipation |
| Persistent and chronic diarrhoea | > 2 weeks | Irritable bowel syndrome, ulcertative colitis, crohn’s disease, colorectal cancer, coeliac disease |
Triple burden of recurrent diarrhoea
| Consequence | Description |
|---|---|
| The HAZ drop | Enteric infection kills more than 1000 per day and stunt 160 million children. Recurrent bouts of diarrhoea reduces catch-up drop |
| The COG hit | Enteric infections rob cognitive development. 1 out of 5 children lose up to 10 IQ pints (Alzheimer’s like deficit). The more diarrhoea episodes, the lower the cognition. |
| The METsyn | Enteric infection may increase adult obesity, cause metabollic syndrome and cardiovascular disease |
Types of diarrhoea
| Type of diarrhoea | Description | Causes |
|---|---|---|
| Secretory | Endogenic secretion of substances that induce fluid and electrolyte shifts in the absence of osmotic gradient | Bacterial toxins, laxatives, hormones (VIP), drugs |
| Osmotic | Osmoles in the lumen create an osmotic gradient with net water secretion and retention | Ingestion of poorly absorbed substrates, carbonated fluids, malabsoprtion of water soluble nutrients |
| Inflammatory | Disruption of the absorptive epithelial structure by pathogens | Gastroenteritis, infectious colitis, allergic colitis, immune deficiency, autoimmune e.g. IBD |
| Dysmotility | Low transit time reduces time for absorption (in the presence of a normal epithelial structure) |
Definition of terms
| Term | Definition |
|---|---|
| Dysentery | Stool that is small in volume, bloody, mucoid, and associated with abdominal pain or toxic appearance. It is commonly caused by Shigella, Campylobacter, and Escherichia coli. |
Causes of infectious diarrhoea
| Type | Examples |
|---|---|
| Viruses (75 – 90%) | Rotavirus, Norwalk, Enteric adenovirus, Calicivirus, Astrovirus |
| Bacteria (< 20%) | Salmonella, Shigella, Campylobacter jejuni, Yersinia enterocolita, Vibrio cholerae, Escherichia coli, Clostridium difficile |
| Protozoa and helminths (< 5%) | Giardia lamblia, Entamoeba histolytica, Cryptosporidium |
- Risk factors for persistent diarrhoea
- Formula feeding
- Age less than 3 month at onset
- Malnutrition
- Immunosuppression
- HIV
- Associated illness
- Nosocomial infection in the hospital
- Causes of non-bloody infectious diarrhea
- Viruses
- Giardia – associated with camping, consumption of (+O & p or + Giardia antigen) stream water, oral-anal sexual contact, severe bleeding
- Bacillus cereus – associated with reheated fried rice, vomiting, and diarrhea
- Staphylococcus aureus – associated with dairy, coleslaw, picnics, vomiting, diarrhea and mini outbreaks
- Clostridium perfringens – associated with meat that has been sitting out too long
- Listeria monocytogenes – associated with deli foods. This has an increased incidence in pregnancy
- Cryptosporidium – associated with HIV CD4 < 100, high ALP, and acid fast positive
- Isospora belli – associated with HIV CD4 < 100, high eosinophil, acid fast positive
- Causes of bloody infectious diarrhea
- Campylobacter – this is the most common cause. It is associated with Guillain-Barre syndrome and reactive arthritis
- Salmonella from poultry, eggs, and milk
- Shigella
- Yersinia
- Enterohemolytic Escherichia Coli (EHEC)
- E. coli O157:H7 (Ass with HUS; never ever ever ever give antibiotics or platelets)
- Entamoeba histolytica
- Vibrio parahemolyticus – this is associated with shellfish consumption
- Vibrio vulnificus – this is associated with liver disease or high iron state
- Differentials
- Gastroenteritis
- Irritable bowel sydnrome
- SSRIs
- Small bowel bacterial overgrowth syndrome
- Constipation
- Coeliac disease
- Clostridioides difficile infection
- Campylobacter infection
- Colorectal cancer
- Roseola infantum
- Non-typhoidal Salmonella
- Giardiasis
- Cow’s milk protein intolerance
- Cow’s milk protein allergy
- Grave’s disease
- Ischaemic colitis
- Crohn’s disease
- Microscopic colitis
- Ulcerative colitis
- Acute mesenteric ischaemia
- Pancreatic cancer
- Acute appendicitis
- Shigellosis
- Erythema infectiousm
- HIV
- Henoch-schonlein purpura
- Ectopic pregnancy
- Reactive arthritis
- Haemolytic uraemic syndrome
- Viral meningitis
- Chronic mesenteric ischaemia
- Measles
- Legionella pneumonia
- Guillain-Barre syndrome
- Dengue fever
- Psittacosis
- Whipple’s disease
- Escherichia coli associated diarrhoea
- Investigations
- Stool culture is the initial investigation of choice. It identifies the pathogenic organisms.
- Stool microscopy for ova, cysts, or trophozites. It detects parasites, e.g., Giardia lamblia, Cryptosporidium parvum, and amoebae.
- Stool enzyme immunoassay (EIA) to detect toxins.
- Stool PCR
- Stool osmotic gap (the normal is between 50-100 mOsm/kg)
- Stool lactoferrin (WBCs) for inflammatory diarrhoea
- Fecal fat
- Flexible sigmoidoscopy or colonoscopy for inflamatory bowel disease or other structural abnormalities
- Gastroscopy for coeliac disease or other malabsorptive disorders
- Abdominal ultrasound for abscesses or gallbladder disease
- Abdominopelvic CT scan for intestinal tuberculosis, malignancy, or mesenteric ischaemia
- Complete Blood Count
- Basic metabolic profile
- Blood cultures
- Treatment
- Inpatient treatment if:
- Hypotensive
- Severe pain
- Fever
- Abdominal tenderness
- Adequate hydration
- Gatorade, Pedialyte, and other isotonic drinks are preferable to water
- Basic food safety education
- For infectious diarrhoea:
- Oral ciprofloxacin (or another fluoroquinolone) +/- metronidazole
- Oral doxycycline if the history suggests V. vulnificus)
- Antibiotics should be avoided in patients with HUS
- For patients with AIDS:
- HAART to increase CD4 count > 100
- TMP-SMX for isospora belli
- Return if diarrhea has gone on for more than 2 weeks
- Inpatient treatment if: