What is pneumonic plague and how does it spread?

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1. 1

   Epidemiologic Determinants for Modeling Pneumonic Plague Outbreaks

   Emerging infectious diseases (Gani & Leach)Published Apr 1, 2004Checked Oct 7, 2026

   “Pneumonic plague poses a potentially increasing risk to humans in plague nonendemic regions either as a consequence of an aerosolized release or through importation of the disease. Pneumonic plague is person-to-person transmissible. We provide a quantitative assessment of transmissibility based on past outbreaks that shows that the average number of secondary cases per primary case (R0) was 1.3 (variance = 3.1), assuming a geometric probability distribution, prior to outbreak control measures. We also show that the latent and infectious periods can be approximated by using lognormal distributions with means (SD) of 4.3 (1.8) and 2.5 (1.2) days. Based on this parameter estimation, we construct a Markov-chain epidemic model to demonstrate the potential impact of delays in implementing outbreak control measures and increasing numbers of index cases on the incidence of cases in simulated outbreaks.”

2. 2

   Transmission dynamics of primary pneumonic plague in the USA

   Epidemiology and Infection (Hinckley et al.)Published Jul 7, 2011Checked Oct 7, 2026

   “Plague is thought to have killed millions during three catastrophic pandemics. Primary pneumonic plague, the most severe form of the disease, is transmissible from person-to-person and has the potential for propagating epidemics. Efforts to quantify its transmission potential have relied on published data from large outbreaks, an approach that artificially inflates the basic reproductive number (R(0)) and skews the distribution of individual infectiousness. Using data for all primary pneumonic plague cases reported in the USA from 1900 to 2009, we determined that the majority of cases will fail to transmit, even in the absence of antimicrobial treatment or prophylaxis. Nevertheless, potential for sustained outbreaks still exists due to superspreading events. These findings challenge current concepts regarding primary pneumonic plague transmission.”

3. 3

   Pneumonia Caused by Yersinia pestis: Plague Pneumonia

   Kluwer Academic Publishers eBooks (Cleri et al.)Published Jan 5, 2006Checked Oct 7, 2026

   “With the first reported case of multidrug-resistant Y. pestis from an epidemic area, the future of treatment and prophylaxis regimens may be problematic, although quinolones and third-generation cephalosporins may hold some promise. Plague, and especially plague pneumonia, in their early presentations are difficult to diagnose. One must maintain a high index of suspicion and be sure to accurately assess a patient’stravel and vector or animal exposure when choosing presumptive therapy for a presumed bacterial pneumonia. A disease that may present itself as a pneumonia, adult respiratory distress syndrome, a surgical abdomen, undifferentiated sepsis with or without DIC, Reye’s syndrome, or any form of lymphadenopathy with or 0. without the above presentations is a diagnostic and treatment challenge. This is especially true in patients with plague pneumonia, where often there will be no second chance at therapy if empiric therapy fails. Untreated, the disease is fatal in 90% to 95% of cases. Appropriate treatment reduces mortality to 5% to 18% (Cleri et al., 1997).”

4. 4

   [Yersinia pestis as a dangerous biological weapon].

   PubMed (Grygorczuk & Hermanowska-Szpakowicz)Published Jan 1, 2002Checked Oct 7, 2026

   “Infection by flea bite results in a bubonic or septicemic plague, possibly complicated by secondary pneumonia. The person with pneumonic symptoms may be a source of a droplet-borne inhalatory infection for other people who consequently develop primary pneumonic plague. Despite a clinical form, plague is a severe infection characterized by a short incubation period, rapid onset and quick progress with mortality exceeding 50% if not treated properly. The pneumonic plague is associated with a particularly rapid progress and the mortality rate of almost 100% if not treated properly. As Yersinia pestis can be easily obtained and cultured and is highly pathogenic for humans, it poses a serious threat of being used for bioterrorism purposes. Artificially created aerosol containing plague bacilli can cause numerous and almost simultaneous cases of primary pulmonic plague in an exposed population. Persons exposed would most likely develop severe pneumonia with rapidly progressing respiratory and circulatory failure. The use of the Yersinia pestis strains resistant to antibiotics typically applied cannot be excluded.”

5. 5

   Risk of Person‐to‐Person Transmission of Pneumonic Plague

   Clinical Infectious Diseases (Kool)Published Mar 29, 2005Checked Oct 7, 2026

   “Plague has received much attention because it may be used as a weapon by terrorists. Intentionally released aerosols of Yersinia pestis would cause pneumonic plague. In order to prepare for such an event, it is important, particularly for medical personnel and first responders, to form a realistic idea of the risk of person-to-person spread of infection. Historical accounts and contemporary experience show that pneumonic plague is not as contagious as it is commonly believed to be. Persons with plague usually only transmit the infection when the disease is in the endstage, when infected persons cough copious amounts of bloody sputum, and only by means of close contact. Before antibiotics were available for postexposure prophylaxis for contacts, simple protective measures, such as wearing masks and avoiding close contact, were sufficient to interrupt transmission during pneumonic plague outbreaks. In this article, I review the historical literature and anecdotal evidence regarding the risk of transmission, and I discuss possible protective measures.”

6. 6

   Yersinia pestis: the Natural History of Plague

   Clinical Microbiology Reviews (Barbieri et al.)Published Dec 8, 2020Checked Oct 7, 2026

   “The Gram-negative bacterium Yersinia pestis is responsible for deadly plague, a zoonotic disease established in stable foci in the Americas, Africa, and Eurasia. Its persistence in the environment relies on the subtle balance between Y. pestis -contaminated soils, burrowing and nonburrowing mammals exhibiting variable degrees of plague susceptibility, and their associated fleas. Transmission from one host to another relies mainly on infected flea bites, inducing typical painful, enlarged lymph nodes referred to as buboes, followed by septicemic dissemination of the pathogen.”