Bioterrorism agents physicians should know
By Phyllis Maguire
The anthrax attacks in 2001 made the threat of bioterrorism painfully real. While physicians should be able to identify and treat chemical agent syndromes, they also need to be able to recognize major bioterrorism agents.
At an Annual Session presentation, Jan E. Patterson, FACP, professor of infectious diseases and pathology at the University of Texas Health Science Center at San Antonio, said clinicians should be able to identify the following six agents:
Inhalational anthrax. While patients usually present with dyspnea and chest pain, the cardinal clinical features are pleural effusion and widened mediastinum visible on X-rays. You need to start antibiotic treatment early to be effective. Use ciprofloxacin or doxycycline, plus one to two additional antibiotics. Doxycycline or ciprofloxacin are also indicated for prophylaxis, while vaccine is available in only limited doses.
Smallpox. Smallpox features a febrile prodrome of two to four days, with temperatures of over 101 degrees. The telltale rash begins on the arms, legs and face—with lesions progressing at the same time. (This is unlike chickenpox, where pox progression is asynchronous.) Smallpox lesions also appear on the palms and soles, while chickenpox does not. Contact and airborne precautions are used for infected patients. Prophylaxis for the disease, which has a 30% mortality rate, is live vaccine given within 2-4 days of exposure.
Plague. Bubonic plague is characterized by buboes of the lymph glands. Patients may also have secondary pneumonia. Pneumonic plague presents with fulminant pneumonia and watery, bloody sputum. Pneumonic plague may be suspected by gram negative diplococci on stain, which shows a bipolar "safety-pin" configuration, and confirmed by blood and sputum culture, or rapid tests such as direct fluorescent antibody or PCR. Use droplet precautions for infected patients.
Tularemia. Patients can contract tularemia in many parts of the country through insect bites, animal exposure, or contaminated food or water. Weaponized tularemia would cause tularemic pneumonia. Victims' X-rays would show peribronchial infiltrates, pneumonia in one or both lobes, pleural effusions, and hilar lymphadenopathy or small discrete infiltrates.
You can diagnose tularemia through blood or sputum culture, or direct fluorescent antibody or PCR. Treat patients with streptomycin, gentamicin, tetracycline or ciprofloxacin. If patients have been exposed, watch them for seven days and treat them with antibiotics if they have a fever.
Botulism. Botulism is characterized by the "5 Ds": diplopia, dysphonia, dysarthria, dysphagia and dyspnea. The key clinical features are descending flaccid paralysis with cranial nerve palsies. Collect clinical specimens from serum, gastric contents, feces or wound tissue to confirm the diagnosis by culture or toxin assay. Provide ventilator support if necessary.
Viral hemorrhagic fever. This class of agents, which includes Ebola and Lassa fever, has mortality rates ranging from 10% to 90%. While symptoms vary with viruses, they can include fever with myalgia and prostration; petechiae, hemorrhage and shock; and neurologic, pulmonary and hepatic involvement. If you suspect this type of agent, take precautions against contact and airborne infection. Treatment is supportive, while you can give ribavirin for Lassa and several other viruses.
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