VACCINATION
Beginning in the 1930s, the Soviet Union used a live attenuated vaccine to immunize tens of millions of persons living in tularemia-endemic areas.88 In
the United States, a live attenuated vac- cine derived from the avirulent live vac- cine strain has been used to protect laboratorians routinely working with F tularensis; until recently, this vac- cine was available as an investiga- tional new drug.89 It is currently un- der review by the US Food and Drug Administration (FDA), and its future availability is undetermined.
In a retrospective study of civilians
working with F tularensis at a US Army research facility, the incidence of acci- dental acute inhalational tularemia among laboratorians declined from 5.70 cases per 1000 person-years of risk at
Figure 3. Gram Stain Smears of the Agents of Anthrax (Bacillus anthracis), Plague (Yersinia pestis), and Tularemia (Francisella tularensis), Demonstrating Comparative Morphology, Size, and Staining Characteristics
A
B
C
A, B anthracis is a large (0.5-1.2 µm × 2.5-10.0 µm), chain-forming, gram-positive rod that sporulates under certain conditions (Gram stain of organism from culture; original magnification ×250); B, Y pestis is a gram-negative, plump, non–spore-forming, bipolar-staining bacillus that is approximately 0.5-0.8 µm × 1-3 µm (Gram stain of smear from infected tissue; original magnification ×250); C, F tularensis is a small (0.2 µm × 0.2-0.7 µm), pleomorphic, poorly staining, gram-negative coc- cobacillus (Gram stain of organism from culture; original magnification ×500) (inset, direct immunofluorescence of smear of F tularensis; original magnification ×400. Sources: A and B, Sherif Zaki, Centers for Disease Control and Prevention; C, Armed Forces Institute of Pathology.
Figure 4. Francisella tularensis Growth at 72 Hours After Inoculation
These Francisella tularensis colonies show character- istic opalescence on cysteine heart agar with sheep blood (cultured at 37°C for 72 hours). Source: Cen- ters for Disease Control and Prevention.
MANAGEMENT OF TULAREMIA AS A BIOLOGICAL WEAPON
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