Plague

Plague is an infectious zoonotic disease driven by the Gram-negative bacterium Yersinia pestis, which establishes persistent ecological cycles among small mammals and their associated fleas ^[2][3]. The pathogen maintains environmental reservoirs through contaminated soils and susceptible animal populations, creating stable natural foci that periodically facilitate cross-species transmission to human communities ^[3].

Following a one- to seven-day incubation period, infected individuals typically present with an acute febrile syndrome characterized by sudden fever, chills, systemic myalgias, profound weakness, vomiting, and nausea ^[1][2]. Clinical progression commonly yields bubonic plague, marked by rapidly enlarging, painful lymph nodes that may suppurate, or evolves into pneumonic and septicaemic variants involving respiratory compromise and hematogenous dissemination ^[2][3]. Untreated pneumonic and septicaemic presentations carry case-fatality ratios between 30% and 100%, underscoring the critical importance of early symptom recognition ^[1][2].

Human plague occurrence is strictly tied to regions where competent animal reservoirs and vector populations overlap with human habitation, with current burdens heavily concentrated in parts of Africa, Asia, and South America ^[1][2]. Since the 1990s, the majority of documented infections have originated in African nations, notably the Democratic Republic of Congo, Madagascar, and Peru, where seasonal epidemic waves frequently align with specific climatic and ecological conditions ^[1][2]. While historical pandemics once caused catastrophic mortality across multiple continents, contemporary disease distribution reflects fragmented zoonotic hotspots rather than sustained human-to-human transmission chains ^[2][3].

Primary human infection typically results from the bite of infected fleas carrying Y. pestis, which deposits the pathogen into the dermis and facilitates lymphatic replication ^[4][2]. Secondary exposure pathways include direct contact with infected animal tissues or bodily fluids, while inhalation of respiratory droplets from individuals or mammals suffering from pneumonic plague enables efficient airborne spread ^[2][3]. Rare instances of gastrointestinal and pharyngeal plague have been linked to the consumption of contaminated raw meat, highlighting additional dietary exposure routes ^[3].

Primary prevention of plague relies fundamentally on the active surveillance of established endemic foci and systematic ectoparasite control . Comprehensive management requires investigating regional animal reservoirs and flea species to develop environmental programmes that clarify the natural zoonotic cycle and restrict pathogen dissemination ^[1]. Long-term reduction in human incidence is driven by continuous monitoring of animal populations coupled with rapid interventions during wildlife outbreaks ^[1]. Additionally, effective containment demands a well-informed healthcare workforce and public vigilance to facilitate rapid diagnosis, administer early antibiotic treatments, enforce isolation measures, and mitigate transmission risks through targeted vector and host control ^[1].

1. 1 World Health Organization. Plague [Internet]. cited 3 Sept 2026. Available from: https://www.who.int/news-room/fact-sheets/detail/plague
2. 2 World Health Organization. Plague [Internet]. cited 3 Sept 2026. Available from: https://www.who.int/health-topics/plague
3. 3 Barbieri R et al. Yersinia pestis: the Natural History of Plague. Clin Microbiol Rev. 2020 Dec 16. PMID: 33298527. doi: 10.1128/CMR.00044-19. PubMed: https://pubmed.ncbi.nlm.nih.gov/33298527/
4. 4 World Health Organization. Plague [Internet]. cited 3 Sept 2026. Available from: https://www.who.int/news-room/questions-and-answers/item/plague