dysentery

Diarrhoea with visible blood

Retain stool consistency, change from baseline and blood observations as distinct evidence supporting classification.

1. Were loose or watery stools and visible blood observed within the same episode? definition
2. Who observed the stool, when, and was the account direct or reported? provenance
3. How did stool frequency and consistency differ from the person's usual pattern? measurement

Syndrome definition and mimics

Attach the classification to an explicit definition and preserve observations that may instead indicate another bleeding presentation.

1. Which clinical or surveillance definition supports the dysentery label? definition
2. Could the report represent isolated rectal bleeding, stool discoloration or occult blood without visible bloody diarrhoea? boundary

Supported cause attribution

Record each causal hypothesis, its supporting evidence and its unresolved alternatives without requiring a single premature diagnosis.

1. Which findings support Shigella, E. histolytica, another infectious cause or a noninfectious explanation? provenance
2. What evidence would change or overturn the current attribution? boundary

Specimen result and limitations

Keep collection timing, prior treatment, organism identification and available susceptibility information together.

1. Which specimen and method produced the result, and when was it collected relative to symptoms and treatment? provenance
2. Does the method distinguish the suspected pathogen from similar organisms or leave clinically relevant uncertainty? boundary
3. What additional testing or susceptibility evidence does the responsible clinician need before acting? action

Current urgency evidence

Record hydration findings, ability to drink, urine output, vital signs and relevant host vulnerabilities with an explicit clinical assessment.

1. What current observations describe hydration, oral intake, urine output and systemic illness? measurement
2. Which age, nutritional, immune or other patient factors alter interpretation of these observations? boundary
3. What escalation is indicated by the applicable clinical guidance and who is responsible for initiating it? action

Episode progression

Compare successive observations and link suspected complications to their own clinical assessments.

1. How have blood in stool, stool frequency, pain, fever and hydration changed since onset and intervention? measurement
2. Do persistent symptoms, recurrent bleeding or new systemic findings require investigation of a complication or alternative diagnosis? action

Supportive care feasibility

Record planned fluid support, ability to receive it and the basis for the selected care setting.

1. What fluid-support plan is documented, and can the person receive and tolerate it? action
2. What findings determine whether the current care setting and reassessment interval remain adequate? boundary

Treatment rationale and safety

Preserve the reason to start, withhold or change treatment. Include review of antimotility exposure; CDC advises against these medicines in bloody diarrhoea. [CDC treatment guidance](https://www.cdc.gov/shigella/treatment/index.html)

1. What suspected or established cause and current guidance justify starting, withholding or changing an antimicrobial? action
2. Have susceptibility results, allergies, patient-specific constraints and antimotility medicine use been reviewed? action
3. What observed response or adverse effect would trigger review of the treatment decision? measurement

Plausible acquisition links

Represent exposures and linked illnesses as hypotheses with dates and evidence.

1. Which food, water, travel, caregiving or sexual-contact exposures occurred before onset, and when? provenance
2. Are there similarly ill contacts or shared exposures that warrant an outbreak-assessment link? boundary

Activity and clearance decisions

Record applicable precautions, reporting decisions and criteria for resuming relevant activities with their issuing authority.

1. Which precautions or activity restrictions apply to this suspected cause, setting and jurisdiction? action
2. Which authority and dated guidance support any reporting, exclusion or clearance requirement? provenance
3. What evidence permits symptom-based episode closure, and what separate evidence is required to release transmission-related restrictions? boundary

Kinds and varieties

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Bacillary dysentery (shigellosis: Shigella dysenteriae, S. flexneri, S. boydii, S. sonnei)
• Amoebic dysentery (invasive intestinal infection by Entamoeba histolytica)
• Epidemic Shiga dysentery (S. dysenteriae type 1)
• Campylobacter colitis presenting as dysentery
• Enteroinvasive E. coli (EIEC) dysentery
• Balantidial dysentery (Balantidium coli)
• Sexually transmitted shigellosis (notably in men-who-have-sex-with-men networks)
• Syndromic bloody diarrhoea as used in WHO IMCI (visible blood in stool, organism not yet identified)

1. Which of these kinds and varieties hold for the sense of dysentery this model covers, and on what evidence? provenance

Identifiers and schemes

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Wikidata - Q129279 - Item for dysentery as a disease.
• MeSH - D004403 - Dysentery; narrower headings D004405 (bacillary) and D004404 (amebic).
• ICD-10 - A03 - Shigellosis (bacillary dysentery), with fourth-character species splits.
• ICD-10 - A06.0 - Acute amoebic dysentery.
• ICD-11 - 1A02 - Shigellosis; amoebic disease is coded under amoebiasis (1A36), not under a single parent 'dysentery'.
• SNOMED CT - 111566002 - Dysentery (disorder); organism-specific descendants are preferred in current coding.

1. Which of these identifiers and schemes hold for the sense of dysentery this model covers, and on what evidence? provenance

Standards and regulation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• WHO Guidelines for the control of shigellosis, including epidemics due to Shigella dysenteriae type 1 (World Health Organization, 2005)
• WHO/UNICEF Integrated Management of Childhood Illness: blood in the stool is classified and treated as dysentery (World Health Organization)
• WHO Model List of Essential Medicines: ciprofloxacin, azithromycin and ceftriaxone for shigellosis; metronidazole or tinidazole (then a luminal agent) for invasive amoebiasis (World Health Organization)
• CDC/CSTE national notifiable disease case definition for shigellosis (Centers for Disease Control and Prevention / Council of State and Territorial Epidemiologists)
• EU case definition for shigellosis used in TESSy reporting (European Centre for Disease Prevention and Control)
• International Health Regulations (2005): not a named IHR disease, but clusters may be assessed as events that may constitute a public health emergency of international concern (World Health Organization)

1. Which of these standards and regulation hold for the sense of dysentery this model covers, and on what evidence? provenance

Real-world use

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Primary-care and IMCI clinics treat any diarrhoea with visible blood as dysentery before an organism is known.
• Hospitals work up acute bloody diarrhoea with stool culture, multiplex PCR, microscopy or antigen tests, then name the disease by organism (shigellosis, amoebic colitis, Campylobacter colitis).
• Outbreak investigation in refugee camps, after floods, in day-care and institutions, and historically in armies and ships.
• Sexual-health and public-health teams investigate shigella clusters among men who have sex with men in high-income cities.
• National laboratories track extensively drug-resistant Shigella because oral options are running out.
• Travel and tropical-medicine clinics distinguish bacillary from amoebic disease because the drugs differ.

1. Which of these real-world use hold for the sense of dysentery this model covers, and on what evidence? provenance

Typical measurements

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Infectious dose (Shigella) - 10-100 - CFU
• Incubation, bacillary (Shigella) - 1-3 (range about 0.5-4) - days
• Incubation, amoebic dysentery - 7-28 (often 1-4 weeks) - days
• Stool frequency in frank dysentery - 8-20 small bloody stools - stools/day
• Duration of untreated bacillary dysentery - 5-7 - days
• Case fatality, untreated S. dysenteriae type 1 epidemics - 5-15 - %
• Fever in bacillary dysentery - 38-40 - °C

1. Which of these typical measurements hold for the sense of dysentery this model covers, and on what evidence? provenance

Failure modes and hazards

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• Person-to-person and sexual spread at a very low infectious dose, including in households, day-care and MSM networks.
• Dehydration, hypoglycaemia and death in young children, the malnourished and the frail.
• Haemolytic uraemic syndrome from Shiga toxin, especially S. dysenteriae type 1 (and from STEC if the case was mislabelled dysentery and given antibiotics).
• Toxic megacolon and colonic perforation, particularly in untreated severe amoebic colitis.
• Amoebic liver (and rarer brain) abscess after intestinal invasion.
• Seizures and toxic encephalopathy in children with shigellosis.
• Reactive arthritis after Shigella or Campylobacter.
• Extensively drug-resistant Shigella leaving few or no reliable oral drugs.
• Wrong drug class: antibacterial therapy does not treat E. histolytica; metronidazole does not treat shigellosis; empiric antibiotics can worsen STEC.

1. Which of these failure modes and hazards hold for the sense of dysentery this model covers, and on what evidence? provenance

Regional variation

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• In WHO/UNICEF child-health programmes across Africa and South Asia the working name is still the syndrome 'dysentery' (blood in stool); US and much of European hospital practice prefers 'infectious colitis' or the organism name.
• S. sonnei predominates in high-income countries; S. flexneri in endemic low- and middle-income settings; S. dysenteriae type 1 caused large late-20th-century epidemics in Central/East Africa and South Asia and is now uncommon.
• Invasive amoebiasis is concentrated in parts of Mexico, the Indian subcontinent, western and southern Africa, and parts of South America, not in high-income temperate cities except among travellers and migrants.
• Azithromycin- and ciprofloxacin-resistant S. sonnei/flexneri now circulate in Europe, North America and Australia, especially in sexual networks.
• Historical English 'bloody flux' and Japanese notifiable 'sekiri' (赤痢) named the same syndrome; modern Japanese and ICD practice split shigellosis from amoebiasis.

1. Which of these regional variation hold for the sense of dysentery this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Reported by the breadth pass; each item needs checking against its source before it becomes normative.

• STEC/EHEC haemorrhagic colitis - Typically little or no fever and few faecal leukocytes; Shiga-toxin/PCR or culture for non-Shigella E. coli; antibiotics are avoided because of HUS risk.
• Ulcerative colitis (first attack) - Repeated negative stool tests for pathogens, chronic relapsing course, and endoscopic/histologic chronic colitis rather than an acute self-limited or outbreak-linked illness.
• Clostridioides difficile colitis - Recent antibiotics or healthcare exposure plus stool toxin/NAAT for C. difficile; not a classical camp or travel dysentery.
• Amoebic versus bacillary dysentery (each other) - Bacillary disease is explosive over hours to a few days with high fever; amoebic disease is more subacute. Microscopy/antigen/PCR for E. histolytica versus Shigella culture/PCR; liver abscess points to amoeba.
• Non-invasive watery diarrhoea (including cholera) - Large-volume watery stool without visible blood or tenesmus; vibrio or enterotoxin work-up rather than invasive colitis.
• Ischaemic colitis - Older patient with vascular risk, sudden left-sided pain, and watershed injury on imaging/endoscopy; stool tests for enteropathogens are negative.
• Enteric fever (typhoid) - Prolonged fever, relative bradycardia and bacteraemia on blood culture; stool is not typically frequent small bloody motions of colitis.
• Childhood intussusception - Currant-jelly stool with intermittent pain and a target sign on ultrasound, not an infectious colitis of the whole colon.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of dysentery this model covers, and on what evidence? provenance