{
  "schema_version": "2.0.0",
  "id": "katz-2009-mononucleosis",
  "name": "Chicago adolescent post-mononucleosis cohort (Katz)",
  "aliases": [
    "Northwestern adolescent IM/CFS cohort"
  ],
  "outbreak_event": null,
  "pathogen_id": "epstein-barr-virus",
  "pathogen_class": "virus",
  "exposure_ascertainment": "serology",
  "design": "prospective_inception",
  "denominator_defined": "yes",
  "denominator_method": "Consecutive adolescents (12-18 y) with serologically confirmed acute infectious mononucleosis, enrolled at diagnosis and followed prospectively.",
  "recruitment_source": "community",
  "time_zero_definition": "Serologically confirmed acute infectious mononucleosis",
  "time_zero_precision": "month",
  "control_group": "none",
  "control_matching_variables": [],
  "n_source_population": null,
  "n_enrolled": 301,
  "n_analysed": 301,
  "followups": [
    {
      "months": 6,
      "n_assessed": 301,
      "n_lost": null
    },
    {
      "months": 12,
      "n_assessed": null,
      "n_lost": null
    },
    {
      "months": 24,
      "n_assessed": null,
      "n_lost": null
    }
  ],
  "max_followup_months": 24,
  "instruments": [],
  "case_definition": "fukuda_1994",
  "pem_assessed": "unclear",
  "objective_measures": [
    "none"
  ],
  "specimens_collected": true,
  "specimen_types": [
    "serum"
  ],
  "acute_phase_specimens": "yes",
  "storage": null,
  "biobank_status": "unknown",
  "consent_future_use": "unknown",
  "external_access": "unknown",
  "contact": null,
  "registration_id": null,
  "funders": [
    "National Institutes of Health (NIAID)"
  ],
  "conflicts": null,
  "data_availability": null,
  "notes": "Strong prospective inception cohort in adolescents with laboratory-confirmed acute EBV mononucleosis and structured re-screening for CFS caseness at fixed timepoints. Shows a declining post-infective CFS rate over two years (13% -> 7% -> 4%), one of the cleanest demonstrations of resolving post-viral fatigue.",
  "publications": [
    {
      "id": "katz-2009",
      "title": "Chronic fatigue syndrome after infectious mononucleosis in adolescents",
      "authors": "Katz BZ, Shiraishi Y, Mears CJ, Binns HJ, Taylor R.",
      "year": 2009,
      "journal": "Pediatrics",
      "doi": "10.1542/peds.2008-1879",
      "pmid": "19564299",
      "url": "https://pubmed.ncbi.nlm.nih.gov/19564299/",
      "open_access": true,
      "is_primary_cohort_paper": true
    }
  ],
  "symptom_inventory_scope": "single_domain",
  "n_symptoms_queried": null,
  "symptom_instrument_note": null,
  "related_cohorts": [],
  "last_verified": "2026-07-20",
  "verified_by": "OSMF research-tracker (web-verified against source)",
  "harmonisation_ruleset": "pais-harmony-v1",
  "observations": [
    {
      "id": "katz-cfs-6mo",
      "cohort_id": "katz-2009-mononucleosis",
      "publication_id": "katz-2009",
      "schema_version": "2.0.0",
      "measure_id": "case-def:cfs",
      "measure_verbatim": "met criteria for chronic fatigue syndrome 6 months after infectious mononucleosis",
      "population": {
        "scope": "whole_cohort",
        "stratum": null,
        "denominator_basis": "assessed_at_timepoint",
        "n_assessed": 301
      },
      "timing": {
        "timepoint_months": 6,
        "timepoint_band": "3-6mo",
        "reference_period": "not_reported",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "unclear",
        "instrument_id": null,
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": 39,
        "denominator": 301,
        "percent": 13,
        "ci": null,
        "precision": "exact"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results/Abstract (13% at 6 months)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    },
    {
      "id": "katz-cfs-12mo",
      "cohort_id": "katz-2009-mononucleosis",
      "publication_id": "katz-2009",
      "schema_version": "2.0.0",
      "measure_id": "case-def:cfs",
      "measure_verbatim": "met criteria for chronic fatigue syndrome 12 months after infectious mononucleosis",
      "population": {
        "scope": "whole_cohort",
        "stratum": null,
        "denominator_basis": "assessed_at_timepoint",
        "n_assessed": 301
      },
      "timing": {
        "timepoint_months": 12,
        "timepoint_band": "6-12mo",
        "reference_period": "not_reported",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "unclear",
        "instrument_id": null,
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": {
          "status": "measured_not_reported"
        },
        "denominator": 301,
        "percent": 7,
        "ci": null,
        "precision": "approximate"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results/Abstract (7% at 12 months)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    },
    {
      "id": "katz-cfs-24mo",
      "cohort_id": "katz-2009-mononucleosis",
      "publication_id": "katz-2009",
      "schema_version": "2.0.0",
      "measure_id": "case-def:cfs",
      "measure_verbatim": "met criteria for chronic fatigue syndrome 24 months after infectious mononucleosis",
      "population": {
        "scope": "whole_cohort",
        "stratum": null,
        "denominator_basis": "assessed_at_timepoint",
        "n_assessed": 301
      },
      "timing": {
        "timepoint_months": 24,
        "timepoint_band": "12-24mo",
        "reference_period": "not_reported",
        "is_cumulative": false
      },
      "method": {
        "ascertainment": "unclear",
        "instrument_id": null,
        "severity_threshold": null,
        "blinded_assessment": "not_reported"
      },
      "value": {
        "type": "proportion",
        "numerator": {
          "status": "measured_not_reported"
        },
        "denominator": 301,
        "percent": 4,
        "ci": null,
        "precision": "approximate"
      },
      "comparator": {
        "group": "none",
        "value": {
          "status": "not_applicable"
        },
        "effect": null
      },
      "harmonised": null,
      "provenance": {
        "source_locator": "Results/Abstract (4% at 24 months)",
        "extracted_by": null,
        "extracted_on": null,
        "verified_by": "OSMF research-tracker (web-verified against source)",
        "verified_on": "2026-07-20",
        "extraction_method": "manual"
      }
    }
  ]
}