Recognize an Illness Associated with Bioterrorism

Health-care providers should be alert for illness patterns and diagnostic clues that might indicate an unusual infectious disease outbreak associated with the intentional release of a biologic agent and should report them. The covert release of a biologic agent may not have an immediate impact because of the delay between exposure and illness onset, and outbreaks associated with intentional releases might closely resemble naturally occurring outbreaks.

Indications of intentional release of a biologic agent

• An unusual temporal or geographic clustering of illness
  • Persons who attended the same public event or gathering
  • Patients presenting with clinical signs and symptoms that suggest an infectious disease outbreak, such as several patients presenting with an unexplained febrile illness, sepsis, pneumonia, respiratory failure, or rash
• An unusual age distribution for common diseases
  • An increase in what appears to be a chickenpox-like illness among Adult patients, but which might be smallpox
• A large number of cases of acute flaccid paralysis with prominent bulbar palsies, suggestive of a release of botulinum toxin.

Syndromes

• Anthrax. A nonspecific prodrome (i.e., fever, dyspnea, cough, and chest discomfort) follows inhalation of infectious spores. Approximately 2-4 days after initial symptoms, sometimes after a brief period of improvement, respiratory failure and hemodynamic collapse ensue. Inhalational anthrax also might include thoracic edema and a widened mediastinum on chest radiograph. Gram-positive bacilli can grow on blood culture, usually 2-3 days after onset of illness. Cutaneous anthrax follows deposition of the organism onto the skin, occurring particularly on exposed areas of the hands, arms, or face. An area of local edema becomes a pruritic macule or papule, which enlarges and ulcerates after 1-2 days. Small, 1-3 mm vesicles may surround the ulcer. A painless, depressed, black eschar usually with surrounding local edema subsequently develops. The syndrome also may include lymphangitis and painful lymphadenopathy. More about anthrax.
• Plague. Clinical features of pneumonic plague include fever, cough with muco-purulent sputum (gram-negative rods may be seen on gram stain), hemoptysis, and chest pain. A chest radiograph will show evidence of bronchopneumonia. More about plague.
• Botulism. Clinical features include symmetric cranial neuropathies (i.e., drooping eyelids, weakened jaw clench, and difficulty swallowing or speaking), blurred vision or diplopia, symmetric descending weakness in a proximal to distal pattern, and respiratory dysfunction from respiratory muscle paralysis or upper airway obstruction without sensory deficits. Inhalational botulism would have a similar clinical presentation as foodborne botulism; however, the gastrointestinal symptoms that accompany foodborne botulism may be absent. More about botulism.
• Smallpox (variaol). The acute clinical symptoms of smallpox resemble other acute viral illnesses, such as influenza, beginning with a 2-4 day nonspecific prodrome of fever and myalgias before rash onset. Several clinical features can help clinicians differentiate varicella (chickenpox) from smallpox. The rash of varicella is most prominent on the trunk and develops in successive groups of lesions over several days, resulting in lesions in various stages of development and resolution. In comparison, the vesicular/pustular rash of smallpox is typically most prominent on the face and extremities, and lesions develop at the same time. More about smallpox.
• Inhalational tularemia. Inhalation of F. tularensis causes an abrupt onset of an acute, nonspecific febrile illness beginning 3-5 days after exposure, with pleuropneumonitis developing in a substantial proportion of cases during subsequent days. More about tularemia.
• Hemorrhagic fever (such as would be caused by Ebola or Marburg viruses). After an incubation period of usually 5-10 days (range: 2-19 days), illness is characterized by abrupt onset of fever, myalgia, and headache. Other signs and symptoms include nausea and vomiting, abdominal pain, diarrhea, chest pain, cough, and pharyngitis. A maculopapular rash, prominent on the trunk, develops in most patients approximately 5 days after onset of illness. Bleeding manifestations, such as petechiae, ecchymoses, and hemorrhages, occur as the disease progresses.More about hemorrhagic fever.

Excerpted from: MMWR Weekly October 19, 2001 / 50(41);893-7