Bioterrorism



Bioterrorism


Anil Mathew

Jonathan P. Moorman



The United States public health system and primary health care providers must be prepared to address various biologic agents, including pathogens that are rarely seen in the United States. High-priority agents (Category A agents, Table 61-1) include organisms that pose a risk to national security because they



  • Can be easily disseminated or transmitted from person to person


  • Result in high mortality rates and have the potential for major public health impact


  • Might cause public panic and social disruption


  • Require special action for public health preparedness


BOTULISM TOXIN



  • Botulinum toxin is the most poisonous substance known. A single gram of crystalline toxin adequately dispersed has the potential to kill more than 1 million people.


  • As a bioterrorist attack, botulinum toxin would be dispersed as an aerosol or by contamination of food supply.


Microbiology



  • Botulinum toxin is produced by Clostridium botulinum, a gram-positive, spore-forming anaerobe.


  • The toxin exists in seven distinct antigenic types, designated letters A to G.


  • Antitoxin directed against one type will have little activity against the other types (absence of cross neutralization).


  • The toxin types can also serve as epidemiologic markers.


Clinical Features



  • All forms of botulism result from absorption of botulinum toxin into the circulation from either a mucosal surface (gut, lung) or a wound.


  • Once the toxin is absorbed into the bloodstream, it binds irreversibly to neuromuscular junctions at peripheral cholinergic synapses. The toxin enters the cell and enzymatically blocks acetylcholine release.


  • Botulism causes an acute, afebrile, descending flaccid paralysis that begins in bulbar musculature, initially developing multiple cranial nerve palsies.


  • Prominent bulbar palsies result in diplopia, dysarthria, dysphonia, and dysphagia.


  • Findings of dry mouth, ptosis, dilated pupils, fatigue, and weakness in extremities, with clear sensorium


  • Severe cases may result in generalized weakness and hypotonia requiring intubation and mechanical ventilation.


  • Recovery may take weeks to months, requiring regeneration of new motor neuron synapses with the muscle cell.


  • Diagnosis is based on clinical suspicion and confirmed by mouse bioassay or toxin immunoassay.










Table 61-1 Category A Agents of Bioterrorism































Agent

Signs and Symptoms

Treatment


Anthrax

Fever, headache, muscle aches, which progress to shortness of breath, chest discomfort, shock, and death


Chest imaging reveals characteristic findings of mediastinal widening and pleural effusions.

Ciprofloxacin 400 mg IV q12h Or


Doxycycline 100 mg IV q12h Plus


Clindamycin 900 mg IV q8h and/or Rifampin 300 mg IV q12h


Switch to PO when stable and continue treatment for 60 days total.


Botulism

Acute, afebrile, descending flaccid paralysis that begins in bulbar musculature, initially developing multiple cranial nerve palsies


Findings of dry mouth, ptosis, dilated pupils, fatigue, weakness in extremities, with clear sensorium


Severe cases may result in generalized weakness and hypotonia requiring intubation and mechanical ventilation.

Supportive care, may require intubation, mechanical ventilation, and parenteral nutrition.


Equine antitoxin, optimally used as soon as possible after diagnosis, may minimize subsequent nerve injury and severity of disease, but will not reverse existent paralysis.


Plague

Fever, cough, and dyspnea, with rapid progression to severe pneumonia with chest pain and hemoptysis.


Gastrointestinal symptoms, including nausea, vomiting, abdominal pain, and diarrhea, may also occur.


Chest x-ray findings of pulmonary infiltrates and consolidations, commonly bilateral, would be expected.

Gentamicin 2.0 mg/kg IV loading then 1.7 mg/kg q8h IV


Or


Streptomycin 1 g q12h IM or IV Alternatives:


Doxycycline 100 mg IV or PO b.i.d. Or


Chloramphenicol 500 mg IV or PO q.i.d.


Tularemia

Febrile illness with development of pleuritis, pneumonitis, and hilar lymphadenitis


Chest imaging may demonstrate bronchopneumonia, pleural effusions, and hilar lymphadenopathy.

Streptomycin 1 g IM q12h × 10 days


Or


Gentamicin 5 mg/kg/day IV × 10 days


Alternatives:


Doxycycline 100 mg IV q12h


Or


Chloramphenicol 1 g IV q6h


Or


Ciprofloxacin 400 mg IV q12h


May switch to PO when stable. Treat for 14-21 days.


Smallpox

Symptoms most often begin 12-14 days after infection, with high fever, malaise, headache, and backache.


A maculopapular rash begins on the face and extremities and spreads to the trunk (centripetal). Lesions are all in the same stage of development. Initially maculopapular, then vesicular, pustules, and scab over on day 8 or 9.

Supportive measures


Consider cidofovir, antivaccinia immunoglobulin.


Prophylaxis: vaccinia immunization


Viral Hemorrhagic Fevers

Fever, rash, body aches, headaches; later signs of progressive hemorrhagic diathesis develop with petechiae, mucous membrane and conjunctival hemorrhage, hematuria, hematemesis, and melena


Disseminated intravascular coagulation and circulatory shock may follow.

Supportive measures


Consider ribavirin and interferon. Yellow fever vaccination





Treatment



  • Person-to-person spread of botulism does not occur; no isolation is necessary.


  • Supportive care: may require intubation, mechanical ventilation, parenteral nutrition


  • Equine antitoxin, optimally used as soon as possible after diagnosis, may minimize subsequent nerve injury and severity of disease, but will not reverse existent paralysis.


ANTHRAX


Microbiology

Tags:
Jun 22, 2016 | Posted by in INFECTIOUS DISEASE | Comments Off on Bioterrorism

Full access? Get Clinical Tree
Get Clinical Tree app for offline access