24 Feb 2005

Plague = Pneumonia: The=20 worst of Anthrax plus the worst of Smallpox

=20 In the past week both the World Health Organization (WHO) (http://www.who.int/) and contributors = to=20 ProMed-mail (http://www.promedmail.org/), as = well as=20 newsmedia (e.g., NY Times, Washington Post) reported an ongoing outbreak = of=20 plague pneumonia causing at least 43 deaths in the Democratic Republic = of the=20 Congo (DRC). Pneumonic = plague is=20 caused by the bacterium yersinia=20 pestis, is rapidly fatal within several days if not treated, and is = spread=20 by respiratory droplets from person-to-person over short distances = (usually less=20 than 6 feet). Thus, = plague=20 pneumonia combines the worst of inhalational anthrax (a bacteria that = can kill=20 patients within days) with the worst of smallpox (person-to-person = respiratory=20 spread).

=20 The WHO has noted multiple outbreaks of bubonic plague (involving = lymph=20 nodes or =93buboes=94, and spread by infected fleas rather than from=20 person-to-person) in several parts of the DRC in 2002 and 2003 = (Weekly=20 Epidemiological Record 2004;79:301-308). Thus, what is unusual about = the current=20 outbreak is that no cases of bubonic plague have been reported and all = of the=20 cases have been of the rare and much more lethal form of plague that = causes a=20 primary pneumonia and is spread person-to-person via respiratory = droplets. It is this pneumonic form of = plague that=20 would be a devastating bioterrorism weapon because of its nearly 100% = mortality=20 rate unless treated early, and the ability to spread person-to-person. = There is=20 no FDA-licensed vaccine against plague.

=20 The US Centers for Disease Control and Prevention (CDC) state on = their=20 website under =93Facts about Pneumonic Plague=94 that: =93To reduce the = chance of=20 death, antibiotics must be given within 24 hours of first symptoms.=20 Streptomycin, gentamicin, the tetracyclines, and chloramphenicol are all = effective against pneumonic plague=94. No mention is made of = ciprofloxacin, a=20 fluoroquinolone antibiotic and it is not FDA-licensed to treat or = prophylax=20 against plague (yersinia = pestis).=20

Nevertheless, = ciprofloxacin is=20 active against plague pneumonia in mice model experiments, as noted by = the WHO=20 in their new (2004) guidance on Public Health Response to Biological and = Chemical weapons. The August 2004 edition of the US military=92s = (USAMRIID Blue=20 Book) guidelines for biowarafe agents includes ciprofloxacin as an = alternative=20 antibiotic for prophylaxis against plague pneumonia in persons exposed = to a=20 plague aerosol (page 40). The Working Group on Civilian Biodefense has = also=20 published their recommendations for the prevention and treatment of = plague when=20 used as a biological weapon and have included ciprofloxacin as an = alternative=20 antibiotic for adults and children in the mass casualty, post-exposure=20 prophylaxis, and contained casualty situations (J Am Med Assn = 2000=20 (May3); 283:2281-2290).

Of note, respiratory = droplet=20 precautions, including the use of surgical masks, are recommended by the = CDC,=20 WHO, USAMRIID and by the Working Group =20 on Civilian Biodefense (Inglesby et al.) for plague pneumonia=20 prevention. Surgical = masks are=20 inexpensive, require no special formalized training in their use, and = may play a=20 crucial life-saving role against plague, a rapidly fatal communicable = disease=20 with no vaccine, and where antibiotic-resistance can occur both = naturally and by=20 design.

Daniel R. Lucey, MD, MPH