Botulism

Botulism is caused by botulinum neurotoxins produced by the bacteria Clostridium botulinum, a highly poisonous gram-positive anaerobic, spore-forming bacillus.1

Human botulism is almost always foodborne, with an incubation period typically ranging from 12 to 36 hours, although symptoms can occur as soon as 2 hours later.  Symptoms include acute, bilateral cranial neuropathies associated with symmetrical descending weakness, without fever and with clear mentation.  Descending paralysis manifests as symptoms of cranial nerve dysfunction and eventually, the disease progresses to respiratory dysfunction as a result of diaphragmatic weakness.1

In bioterrorism cases, botulinum toxin might be used to contaminate food supplies (GI botulism) or most likely be distributed by aerosol form (inhalational botulism).11,12

The diagnosis of botulism is primarily based on clinical presentation and history, although local epidemiologists can also play a role.

Treatment involves supportive care and heptavalent botulism antitoxin (HBAT) and mechanical ventilation. HBAT is FDA approved, but only available through the CDC Strategic National Stockpile (SNS). To request it, clinicians should contact the staff of their local or state health department who will acquire the antitoxin via the CDC. If health department officials are unavailable, emergency consultation is available from the CDC Emergency Operations Center.

Plague

The bacterial cause of plague is Yersinia pestis, an aerobic gram-negative coccobacillus. Although most cases occur in rural Africa, plague occurs in the United States as well.  Human infection can occur via an infected fleabite, direct contact with infected animal tissue or secretions, or via aerosolized inhalation.1

The incubation period for plague is ~2–7 days. There are 3 forms of plague: bubonic, septicemic, and pneumonic plague, with bubonic plague being the most common clinical form. Initial symptoms include fever, weakness, and headache. Within 24 hours of symptom onset, the bubo (painful regional lymph node swelling) presents, and can be very tender on palpation.1

Although the untreated mortality rate for bubonic plague is high, it is reduced to <5% if detected early and treated with early, effective antimicrobial therapy4 (Table 5). Antibiotic therapy consisting of oral doxycycline is also indicated for PEP following biologic disaster or exposure to plague, specifically in asymptomatic individuals with direct close contact with patients with pneumonic plague, exposure to infectious body fluids, or aerosolized exposure to bioterrorism attack.4,13,14

A potential bioterrorist aerosolized spread should also be suspected in an area with abnormally large numbers of previously healthy individuals who develop severe, rapidly progressive pneumonia with hemoptysis, although the confirmatory diagnosis is usually made by obtaining cultures of infectious fluid and identifying Y. pestis.4

Tularemia

Tularemia, an infectious bacterial zoonotic disease, affects animals and human beings, and is caused by Francisella tularensis, small aerobic gram-negative coccobacilli with 2 clinically significant subspecies of which type A is the most virulent.1

Infectious exposures can occur from bites from mosquitos, ticks, or horseflies, contact with contaminated animal tissue or fluids, ingestion of contaminated food or water; or inhalation of infectious aerosol droplets.1Aerosolized transmission is the most likely route of dissemination as a biological weapon in a terrorist attack.

The definitive diagnosis can be made by culture of infected fluid (e.g., sputum) or tissue and recovery of F. tularensis. If tularemia is suspected, the microbiology laboratory should be notified to take special safety precautions in processing the specimen.

Pharmacotherapies for tularemia are listed in Table 6.