Review: Treatment Recommendations for Biological Disasters

Biological disasters can be attributable to a host of factors and take many forms (Table 1). A recent review¹ by Narayanan et al aims to educate clinicians in disaster preparedness and response by focusing on agents of clinical epidemic significance and bioterrorist national security.

The Centers for Disease Control and Prevention (CDC)^2,3 classifies key biological agents into 3 categories: A, B, and C. The review covers Category A agents, as well as the Zika virus. (Table 2)

Anthrax

Anthrax is caused by an aerobic, gram-positive, spore-forming, exotoxin-producing bacillus called B. anthracis, whose toxins lead to disease in both animals and human beings.¹

In human beings, the 3 primary forms of anthrax are cutaneous, gastrointestinal (GI), and inhalational. Injection anthrax is a relatively new and rare form of cutaneous anthrax, which can affect injection drug users.¹

Bacteremia can lead to manifestation of anthrax in sites secondary to the primary form, including the CNS, which is associated with meningitis after systemic spread.¹

Cutaneous anthrax, which is the most common form (95%) of natural cases in human beings, can occur even after minimal trauma or breaks in the skin. The incubation period is ~1 to 12 days, beginning with a small painless or pruritic papule and progressing to an ulcer, then the development of scab (eschar) that falls off without a residual scar.¹

Appropriately treated cases of cutaneous anthrax are rarely fatal, but untreated cases can spread hematogenously, causing potentially fatal systemic illness and toxin production.⁴

GI anthrax is uncommon in human beings and is associated with eating undercooked meat from an infected animal.¹ The incubation period is ~1 to 6 days.⁴ Symptoms can include fever, severe pharyngitis, oral or pharyngeal edema or ulcers, and dysphagia and, if severe, nausea, vomiting, abdominal pain, bloody diarrhea, hematemesis, ascites, and sepsis and, if untreated, secondary bacterium and invasion of other body sites.^4,5

Inhalation anthrax is the most fatal form of the disease, and most likely to be the route of dissemination for an intentional bioterrorist attack.¹ Since natural cases are rare, it should be assumed that any case is the result of intentional release until proven otherwise.¹

CNS anthrax (meningitis) is a common secondary complication of GI or inhalation anthrax, and most commonly occurs with severe advanced systemic disease.⁶

Anthrax is diagnosed by clinical presentation as well as microbiologic confirmation by culturing B. anthracis. Other options include culturing from sites of infection and serologic testing and polymerase chain reaction (PCR)-based assays.¹

Treatment of anthrax varies, based on the form and type of exposure leading to the disease. Beyond pharmacotherapy, critical care measures (hemodynamic support, mechanical ventilation, surgical intervention, and general sepsis treatment protocols) are essential.

Intravenous (IV) antibiotics with bactericidal and protein-synthesis inhibitor agents are the mainstay of systemic anthrax treatment (Table 3). In addition, the US Food and Drug Administration (FDA) has approved 3 antitoxin therapies to be used in combination with appropriate antibiotic therapy^7-9 (Table 4). Moreover, the Advisory Committee on Immunization Practices recommends postexposure prevention (PEP) consisting of anthrax vaccine absorbed (AVA) and antimicrobial agents.¹

The authors note that treatment recommendations are contingent on availability of resources, which may need to be adjusted in the event of a shortage.¹⁰