Infectivity of pneumonic plague

BMJ 1994; 309 doi: https://doi.org/10.1136/bmj.309.6965.1369a (Published 19 November 1994) Cite this as: BMJ 1994;309:1369
  1. P Cowling,
  2. P Moss
  1. Department of Microbiology, Royal Hallamshire Hospital, Sheffield S10 2JF
  2. Department of Infectious Diseases

    EDITOR, - In a press release issued by the Department of Health the chief medical officer, Dr Kenneth Calman, stated that the risk of person to person transmission of pneumonic plague was considered to be low1; this opinion has been reiterated during numerous interviews in the media. Dr Calman is also quoted by Claudia Court as saying that it is rare for plague to be transmitted person to person.2 Dr Barbara Bannister ascribes this low infectivity to the larger, heavier sputum particles that she believes are produced in pneumonic plague.2

    These comments are at variance with our understanding of pneumonic plague as a highly infectious disease. Our training has taught us this, and we in turn teach it to others. A glance at many textbooks on infectious diseases or microbiology will support this view. Christie refers to pneumonic plague as “highly infectious and highly lethal” and comments on the quality of the sputum as “watery, not viscid, teeming with Yersiniae.”3 The recommendations of the United States Centers for Disease Control state that pneumonic plague may be highly contagious and that untreated plague pneumonia is an epidemiological emergency.4

    Reports of outbreaks of pneumonic plague provide further evidence of its high infectivity. For example Tieh et al described such an outbreak in Mukden, China, in which the index patient infected five casual acquaintances at a dinner and then, through a cascade of contacts, a further 34 people were infected within one month. All but three died, including the medical attendant of one of the patients.5

    We agree that the possibility of a major outbreak of pneumonic plague in Britain is remote because of heightened awareness and the relatively sophisticated epidemiological surveillance system that is in place. To say that an outbreak of pneumonic plague is unlikely, however, is quite different from saying that the disease is of low infectivity. Such comments may send the wrong message to travellers who are at risk of coming into contact with a person proved to have or suspected of having the disease and may have the effect of lowering their vigilance.


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