Criteria for dysentery
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Based on my medical knowledge, here is a comprehensive overview of the criteria for dysentery:
Dysentery: Diagnostic Criteria
Definition
Dysentery is an inflammatory disorder of the intestine — primarily the colon — characterized by bloody, mucoid diarrhea accompanied by systemic features of infection. It is broadly divided into two types:
| Feature | Bacillary Dysentery (Shigellosis) | Amoebic Dysentery |
|---|---|---|
| Causative agent | Shigella spp. | Entamoeba histolytica |
| Onset | Acute (hours–days) | Gradual (days–weeks) |
| Fever | High-grade, common | Low-grade or absent |
| Stools | Frequent, small-volume, blood + mucus + pus | Blood and mucus, less frequent |
| Tenesmus | Prominent | Present |
| Abdominal pain | Severe, crampy | Mild to moderate |
| Systemic toxicity | Marked | Mild |
Clinical Diagnostic Criteria
Core Clinical Features (required for diagnosis)
- Diarrhea — loose or liquid stools, typically ≥3/day
- Visible blood and/or mucus in stools (hallmark)
- Tenesmus — painful straining with defecation, sensation of incomplete evacuation
- Abdominal pain/cramps
Supporting Features
- Fever (more common in bacillary)
- Nausea and vomiting
- Dehydration (varies by severity)
- Rectal urgency
WHO Case Definition
The WHO defines dysentery as:
Diarrhea with visible blood in the stool, regardless of frequency.
This is the standard used in endemic/resource-limited settings and guides empiric treatment decisions.
Laboratory Criteria
| Investigation | Bacillary | Amoebic |
|---|---|---|
| Stool microscopy | Pus cells, RBCs, no trophozoites | E. histolytica trophozoites with ingested RBCs |
| Stool culture | Shigella growth on MacConkey/XLD agar | N/A |
| Stool antigen test | — | E. histolytica ELISA (distinguishes from E. dispar) |
| Serology | — | Amoebic antibodies (useful in extraintestinal disease) |
| CBC | Leukocytosis, left shift | Mild leukocytosis |
| Proctoscopy/sigmoidoscopy | Diffuse mucosal inflammation, friability | Flask-shaped ulcers with normal intervening mucosa |
Severity Classification (Shigellosis — WHO)
| Grade | Features |
|---|---|
| Mild | <4 stools/day, no dehydration, afebrile or low-grade fever |
| Moderate | 4–10 stools/day, mild dehydration, fever |
| Severe | >10 stools/day, high fever, marked dehydration, toxicity |
| Very severe / Toxic | Ileus, altered sensorium, septic shock, HUS |
Differential Diagnosis to Exclude
- Inflammatory bowel disease (Crohn's, UC) — chronic course, no fever
- Campylobacter/Salmonella gastroenteritis — culture differentiates
- EHEC (E. coli O157:H7) — bloody diarrhea without fever ("afebrile bloody diarrhea"), risk of HUS
- Intussusception (in children) — "redcurrant jelly" stool, colicky pain
- Ischemic colitis — older patients, vascular risk factors
Key Distinguishing Point
In clinical practice, the presence of blood and mucus in stool + tenesmus is sufficient to label a case as clinical dysentery and initiate empiric treatment (especially in endemic regions). Microbiological confirmation guides targeted therapy.
Criterias for dysentry
The criteria for dysentery were just covered above — here's a quick recap of the key diagnostic criteria:
Core Criteria (Clinical Diagnosis)
- Bloody, mucoid diarrhea — visible blood and/or mucus in stool (hallmark)
- Tenesmus — painful urge to defecate with sensation of incomplete evacuation
- Abdominal cramps/pain
- Diarrhea — ≥3 loose stools/day
WHO Case Definition
Diarrhea with visible blood in stool, regardless of frequency.
By Type
| Criterion | Bacillary (Shigella) | Amoebic (E. histolytica) |
|---|---|---|
| Onset | Acute | Gradual |
| Fever | High-grade | Low/absent |
| Stool | Frequent, small, blood + pus + mucus | Blood + mucus, less frequent |
| Microscopy | Pus cells, RBCs | Trophozoites with ingested RBCs |
Do you have a specific aspect you'd like to explore further — such as treatment, complications, or pediatric criteria?
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