typhoid fever

Episode classification

Record the evidence and named definition supporting the current typhoid classification.

1. What definition establishes suspected, probable or confirmed typhoid in this clinical or surveillance context? definition
2. What evidence separates this episode from paratyphoid, other Salmonella infections and competing febrile illnesses? boundary

Test interpretability

Blood culture is central to diagnosis; negative results and serology require explicit limitations. [CDC clinical guidance](https://www.cdc.gov/typhoid-fever/hcp/clinical-guidance/index.html)

1. Which laboratory report identifies Typhi, using what specimen and method, collected when relative to onset and antibiotics? provenance
2. What unresolved sampling or test limitations require further diagnostic review before confirming or excluding typhoid? action

Plausible acquisition

Typhoid commonly spreads through food or water contaminated by human faeces. [WHO typhoid fact sheet](https://www.who.int/news-room/fact-sheets/detail/typhoid)

1. Which residence, travel, food, water or infected-contact exposures preceded onset, and on what dates? measurement
2. Which exposures are reported, independently corroborated or linked by an investigation? provenance

Transmission opportunities

Record food preparation, sanitation conditions and relevant contacts alongside evidence of shedding.

1. During which periods did the person prepare food for others or have contact circumstances relevant to faecal-oral transmission? measurement
2. Which precautions or contact assessments are indicated by the responsible public-health authority? action

Clinical trajectory

Track fever, gastrointestinal symptoms and functional change without requiring every typical symptom.

1. When did fever and other symptoms begin, and how have measured temperature and clinical observations changed? measurement
2. Which observations support improvement, deterioration or reconsideration of the typhoid attribution? boundary

Severe disease evidence

Relevant serious complications include gastrointestinal bleeding, intestinal perforation and encephalopathy. [CDC clinical guidance](https://www.cdc.gov/typhoid-fever/hcp/clinical-guidance/index.html)

1. What examination, laboratory or imaging evidence supports or argues against each suspected complication? measurement
2. Which findings meet the applicable protocol's criteria for urgent referral, hospital assessment or specialist intervention? action

Susceptibility-informed review

Record susceptibility results and acquisition history used to inform treatment. [CDC clinical guidance](https://www.cdc.gov/typhoid-fever/hcp/clinical-guidance/index.html)

1. Which isolate results, dated guidance and acquisition evidence support the clinician's treatment choice? provenance
2. Do new susceptibility results or patient-specific constraints require review of the current regimen? action

Response and nonresponse

Record response criteria and reasons for reassessment without equating continuing fever alone with resistance.

1. How have fever and overall condition changed relative to doses actually received and treatment interruptions? measurement
2. When does the applicable protocol call for reassessment of resistance, inadequate exposure, a persistent focus or an alternative diagnosis? action

Recovery and recurrence

Link recurrent fever to the earlier episode without automatically assigning relapse or reinfection.

1. What dated observations establish clinical recovery or another episode outcome? measurement
2. If illness recurs, what timing, exposure and microbiological evidence supports relapse, reinfection or an unrelated cause? boundary

Shedding status

People may continue shedding Typhi after symptoms resolve. [WHO typhoid fact sheet](https://www.who.int/news-room/fact-sheets/detail/typhoid)

1. Which dated follow-up specimens establish detected shedding or negative results, and what remains untested? measurement
2. Which duration and evidence criteria define chronic carriage in the adopted reference? definition

Notification and clearance

Record applicable reporting and return-to-activity requirements; follow-up clearance depends on local public-health guidance. [CDC Yellow Book](https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/typhoid-and-paratyphoid-fever.html)

1. Which authority and dated rule govern notification, food-handling restrictions and return to work, school or childcare? provenance
2. What outstanding tests, reviews or documented decisions must be completed before restrictions can be lifted? action

Kinds and varieties

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

1. Which of these kinds and varieties hold for the sense of typhoid fever 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.

1. Which of these identifiers and schemes hold for the sense of typhoid fever 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.

1. Which of these standards and regulation hold for the sense of typhoid fever 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.

1. Which of these real-world use hold for the sense of typhoid fever 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.

1. Which of these typical measurements hold for the sense of typhoid fever 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.

1. Which of these failure modes and hazards hold for the sense of typhoid fever 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.

1. Which of these regional variation hold for the sense of typhoid fever 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.

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