Plague Outbreak Toolbox

Plague Outbreak Toolbox

Updated | April 2024

Welcome to the Plague Outbreak Toolbox

 

Key reference documents

 

 

Case definitions

WHO suggested outbreak case definition

From WER 23, 2021, 96, 238-40

Suspected case:
  • Clinical presentation suggestive of plague :
    • sudden onset of fever, chills, headache, severe malaise, prostration, painful swelling of lymph nodes; or
    • cough with blood-stained sputum, chest pain, difficulty in breathing
      AND

  • Epidemiological context suggesting possible exposure to plague:

    • Exposure to infected humans or animals; or
    • Residence in or travel to a known endemic focus within 10 days prior to onset of the disease
Probable case:
  • A suspected case;
    AND
  • ONE of the following:
    • F1 antigen positive in bubo aspirate, sputum, blood, or post-mortem tissues by F1RDT or DFA;
    • Single anti-F1 serology positive without evidence of previous Y. pestis infection or vaccination;
    • Direct microscopy in a clinical sample, positive for gram-negative coccobacilli that display bipolar staining with Wayson or Giemsa stain

Confirmed case:
  • A suspected case
    AND
  • At least ONE of the following criteria
    • Isolation of Y. pestis from a clinical sample - must have appropriate colony morphology and be identified as Y. pestis based by at least two of the following:
      • phage lysis at 20-25ºC
    • biochemical profile
    • F1 antigen detection
  • Seroconversion or a 4-fold difference in anti-F1 antibody titer in paired serum samples drawn at least 2 weeks apart
  • Y. pestis DNA positive by species-specific PCR on either clinical sample or culture according to standard practice

    DFA: direct fluorescence assay; DNA: deoxyribonucleic acid; F1RDT: rapid diagnostic test based on F1 antigen; PCR: polymerase chain reaction.

WHO other definition

Definition of a contact of a case:

From: Interregional meeting on prevention and control of plague, Antananarivo, Madagascar 1–11 April 2006 (Geneva: World Health Organization; 2006):

“Persons who have come in contact within a closed space (e.g. room, vehicle, barrack, jail) with the suspected pneumonic plague patient during the two days prior to the development of symptoms in the suspected pneumonic plague patient until two days after the suspected pneumonic plague patient has started appropriate antimicrobial treatment should receive appropriate antimicrobial post-exposure prophylaxis if the exposure has occurred within the previous seven days.”

Encounters with plague: tracing and preventing illness (World Health Organization; 2017).

Definition of a Not a case /discarded case

Suspected case AND either:

• at least TWO of the following laboratory tests (F1RDT, DFA against F1 antigen, direct microscopy, convalescent serology, culture, PCR) are conducted AND they are negative

OR

• When no confirmatory tests can be performed, TWO negative F1RDT on two clinical specimens collected with 24 hours interval

 

 

Data collection tools

 

 

Laboratory confirmation


 

 

Training

 

Other resources