Plague has killed millions of people during the past 25 centuries, and the disease reappeared in several countries during the 1990s. Consequently, plague was categorized as a re-emerging disease. Human plague outbreaks continue to be reported, including an outbreak of pneumonic plague in Madagascar in 2017. Plague is an acute bacterial infection caused by Yersinia pestis. Although effective antimicrobials are available, plague still has high mortality because most outbreaks take place in remote places, where proper diagnosis and treatment remain challenging. Early identification of the disease is crucial to ensure prompt treatment and better outcomes. Pneumonic plague is highly contagious and of particular concern because of the high risk of triggering epidemics. Thus, plague is both a medical and a public health emergency. These guidelines were developed in accordance with the WHO handbook for guideline development. A WHO Steering Group, led by the responsible technical officer, developed the draft scope of the guidelines and the key questions to be addressed. The Steering Group selected the members of the Guideline Development Group (GDG) to ensure diverse areas of expertise were represented, including clinicians, microbiologists, public health professionals, researchers and an anthropologist. The Steering Group also commissioned technical advisers to lead the Evidence Review Team and provide methodological support. The GDG assisted with developing the final scope of the guideline and defining the key areas to be addressed, and also formulated the recommendations.

Three key areas were selected to be addressed:

(i) the use of rapid diagnostic tests (RDTs) for diagnosing plague in different contexts; (ii) the choice of antimicrobials for treating the different forms of plague, including whether fluoroquinolones should be introduced as a first-line medicine of choice; and (iii) the use of personal protective equipment in case of exposure to the dead body of a person who was infected with plague. The Evidence Review Team conducted systematic reviews to address each of the three key areas. At a meeting in Antananarivo, Madagascar, on 20–21 September 2019, the GDG interpreted the main findings of the systematic reviews as they applied to each key question and formulated evidence-based recommendations following the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. For each key question, there was discussion about the certainty of the evidence, desirable and undesirable effects, values and preferences, cost, acceptability, equity, feasibility and barriers to implementation. The GRADE evidence-to-decision tables were used to facilitate consensus and record the decision of the GDG. The GDG developed final recommendations where possible and graded each of them as strong or conditional. The final guidelines were written by the Evidence Review Team.