Plague in the 21st Century: Global Overview and Perspectives in Brazil

Yersinia pestis , the causative agent of plague, evolved from Y. pseudotuberculosis about 6,000 years ago and remains a relevant zoonotic pathogen in the 21st century. Although associated with major historical pandemics, a significant number of human cases are still reported annually, resulting in hundreds of deaths from its most notable forms, bubonic and pneumonic. Knowledge of the epidemiology of this infection is therefore essential for healthcare professionals in the differential diagnosis of febrile syndromes. To estimate the current prevalence of human Y. pestis infections and to evaluate plague case fatality rates in its most common forms. A literature review was conducted exclusively in the PubMed/PMC database, including epidemiological studies, case series, and surveillance analyses published between 1990 and 2023. Articles presenting quantitative data on human cases, regional distribution, and case fatality rates were selected. Between 2000 and 2010, 21,725 plague cases and 1,612 deaths were reported globally, resulting in an approximate case fatality rate of 7.4%. In the United States, from 1900 to 2012, 1,006 cases were recorded, with a recent average of seven cases per year, mainly concentrated in the western states. In Brazil, active bubonic plague foci persisted until the 1960s, totaling more than 2,000 documented cases between 1936 and 1956. Studies identified continued presence of Yersinia pestis in rodents and fleas in the Northeast until 2005, maintaining potential risk of reemergence, although no recent human cases have been reported. Entomological and animal surveillance remains active in these regions. Regarding severity, the case fatality rate for treated bubonic plague is around 8–10%, while for pneumonic plague, without rapid intervention, it can exceed 50%. These data reinforce that although plague is currently rare, it remains a relevant zoonosis, especially in areas with confirmed circulation of Yersinia pestis in wild reservoirs. The high lethality of pneumonic forms and persistence of natural foci, as historically observed in Brazil and still present in other regions worldwide, make the maintenance of continuous epidemiological surveillance, environmental monitoring, and rapid response strategies indispensable to prevent reemergence.