4 October, 2007
As with the Anthrax attacks of 2001 remember that skin lesions have occurred with aerosol-transmitted Tularemia.
If a bioterrorism attack were to occur using aerosolized Francisella tularensis bacteria, then inhalational tularemia (“pneumonia”) would occur. Oculoglandular and oropharyngeal manifestations were also included with pneumonic tularemia as part of a preliminary case definition in 2005 following a possible airborne exposure in the US. As with the skin manifestations of anthrax in persons exposed to the spores sent through the mail in 2001, however, skin lesions can occur with airborne tularemia and thus should be considered in the search for symptomatic patients following a possible aerosol attack.
One of the largest reported civilian outbreaks of airborne tularemia, involving at least 676 persons, occurred in northern Sweden in the autumn of 1966 and winter of 1967 (Dahlstrand, Sverker et al. “Airborne Tularemia in Sweden” Scandinavian Journal of Infectious Diseases 1971;3:7-16). The cause of this outbreak was attributed to inhalation of dust from hay that contained Francisella tularensis from vole feces. Of note, infected skin ulcers were found in 44 of the 405 patients (11.6%) who had serologically confirmed infection with F. tularensis.
In addition, 142 (35%) of these 405 serologically-confirmed patients with airborne tularemia showed skin manifestations “generally occurring 2-3 weeks after onset of the disease. In approximately 50% of the cases where a description of the manifestations was available there was an erythema multiforme-like exanthem on the hands, arms, or legs, while approximately 20% had symptoms of erythema nodosum with reddish-blue, tender infiltration on the legs” (p. 13-14).
The authors of the 1971 publication from Sweden contrasted the more common occurrence of infected ulcers after infection with F. tularensis by direct contact with an infected hare or via mosquitoes than by airborne exposure. In 2007, however, the lesson for biopreparedness is that nearly 12% of patients exposed to naturally-occurring airborne Francisella tularensis developed infected ulcers and thus our initial case definitions and clinical surveillance algorithms used in the search for symptomatic patients should include skin lesions.
If a bioterrorism attack occurs with Francisella tularensis optimized in terms of size (small), concentration (high), strain (virulent), and/or antibiotic resistance (multidrug), then an even higher percent of persons may have skin lesions.
Daniel R. Lucey, MD, MPH
Director, Center for Biologic Counterterrorism and Emerging Diseases
EROne Institutes Dept of Emergency Medicine, Washington Hospital Center
Adjunct Professor, Department of Microbiology and Immunology
Georgetown University Medical Center, Washington DC
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