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  1. Case Definitions/

Open Syndrome Probable Legionnaires' Disease

Authors: Public Health England

Location: England

Purpose #

Case definition for a probable case of Legionnaires’ disease in the context of an outbreak

The definition #

A case with clinical or radiological diagnosis of pneumonia but no microbiological evidence for confirmation of Legionella infection (above) is considered a probable case where the location and onset date(s) meet the outbreak-specific case definition for the exposure category

Machine-readable definition #

The definition is available in JSON format following the Open Syndrome v1.0 specification:

{
   "category": "suspected",
   "definition_type": "case_definition",
   "description": "Case definition for a probable case of Legionnaires' disease in the context of an outbreak",
   "human_readable_definition": "A case with clinical or radiological diagnosis of pneumonia but no\nmicrobiological evidence for confirmation of Legionella infection (above) is\nconsidered a probable case where the location and onset date(s) meet the\noutbreak-specific case definition for the exposure category",
   "inclusion_criteria": [
     {
       "logical_operator": "AND",
       "name": "Suspected case of pneumonia and exposure to an outbreak",
       "type": "criterion",
       "values": [
         {
           "description": "Clinical or radiological diagnosis of pneumonia",
           "name": "Pneumonia",
           "type": "diagnosis"
         },
         {
           "description": "Location and onset date(s) meet the outbreak-specific case definition for the exposure category: community-acquired, healthcare-associated and travel-associated.",
           "name": "Outbreak exposure",
           "type": "epidemiological_history"
         }
       ]
     }
   ],
   "keywords": [
     "Legionnaires' disease"
   ],
   "language": "English",
   "location": "England",
   "open_syndrome_version": "1.0.0",
   "organization": "Public Health England",
   "published_at": "2025-02-08T13:23:40Z",
   "published_by": [
     "Open Syndrome Initiative"
   ],
   "published_in": "https://opensyndrome.org",
   "references": [
     {
       "url": "https://www.gov.uk/government/publications/legionnaires-disease-clinical-case-definitions/legionnaires-disease-case-definitions"
     }
   ],
   "scope": "specific",
   "status": "draft",
   "target_public_health_threats": [
     "Legionnaires' disease"
   ],
   "title": "Open Syndrome Probable Legionnaires' Disease",
   "version": "1.0.0"
 }

Using the Definition #

Healthcare organizations can implement this definition through:

  • Direct integration with surveillance systems
  • API endpoints for real-time validation
  • Manual case verification processes

Next Steps #

We encourage:

  • Clinical feedback on the definition criteria
  • Technical feedback on the implementation format
  • Suggestions for additional symptoms or signs
  • Reports of implementation experiences

Get Involved #

We welcome contributions and feedback from the community.