A Medical Doctor’s Perspective on Anthrax
With the recent cases of anthrax occurring in New York and Connecticut, an MD breaks down the dangers of this devastating infectious disease.
Published March 1, 2002
By Philip S. Brachman, MD
Academy Contributor

Recent bio-terrorist events have resulted in the first cases of inhalational anthrax reported in the United States since the cases that were summarized in the article in the Annals of the New York Academy of Sciences, published in 1980. Five deaths have occurred among the 11 recent cases in the Unites States, making this the first successful bioterrorist event using B. anthracis. Investigations of the events have produced some new information concerning inhalational anthrax.
While the clinical aspects are generally similar to those reported in the initial article, the presence of a cough appears to be more prominent in the recent cases.
Recognizing that the initial symptoms of inhalational anthrax resemble those of the common cold or influenza, it is important to note that none of the current cases reported rhinitis as a symptom. This may be an important notation when initially considering the diagnosis on a patient with a potential exposure to B. anthracis.
New Diagnostic Techniques
On physical examination, the widening of the mediastinum has again been noted. Plural effusions and pulmonary infiltrates have been previously noted, though the former are more prominent among the current cases. As before, pneumonia is not present.
New diagnostic techniques have been developed, including the use of PCR and immunohistochemical staining of tissue, which allow more rapid diagnosis. Serological testing has advanced from the earlier days, which also has aided in the diagnosis. Molecular typing, when performed, has helped in associating cases with each other and with environmental sources of infection.
Successful treatment of six of the 11 recently diagnosed patients is significant. The previous mortality rate in such cases was reported to be 90%. This rate in recent cases has been lowered due to earlier recognition of the potential diagnosis, immediate treatment with large intravenous doses of effective antibiotics, use of pulmonary respirators and better attention to the use of intravenous fluids and medications.
Concerning antibiotic therapy, ciprofloxicin and doxycycline, when given intravenously and as soon as possible, have been important in assisting in the recovery of patients. Another important aspect of the recent events has been the use of prophylactic antibiotics for individuals exposed to aerosols of B. anthracis. It is recommended that prophylacsis be continued for 60 days –– based on the potential persistence of spores in the mediastinal lymph nodes.
New Epidemiological Features
New epidemiological features have also been described. We have learned that spore-bearing particles may be extremely small, possibly one micron in size. This allows the spores to pass through a paper envelope and contaminate the environment. Aerosols containing refined, highly concentrated B. anthracis-bearing particles have spread throughout buildings, either by airflow or movement of people, or movement of contaminated mail or equipment. As a result, distant environmental areas –– not directly related to where the envelopes containing the B. anthracis spores were opened –– have been contaminated.
The contamination of tertiary envelopes (envelopes contaminated from secondary contaminated envelopes that had contact with B. anthracis particles from the primary envelope) may be the source of infection for the two recent cases: in New York and Connecticut. Careful investigations have not identified any other source of these two infections.

A factor that may have influenced differences between the previous cases of inhalational anthrax and the bio-terrorist cases was the B. anthracis-containing aerosol. In previous cases, the aerosol probably contained particles of a wide range of sizes. The bio-terrorist aerosol was pure B. anthracis particles, with a large percentage of particles in the range of one to two microns. We still do not have evidence concerning the dosage of B. anthracis organisms necessary to cause disease, but some suspect it might be a relatively small dose.
The current investigations have assisted in identifying improved methods for environmental sampling to determine the limits of the spread of B. anthracis. Several rapid assay methods have been developed, but they have not been adequately tested to determine their sensitivity and specificity. Additionally, information should be gained from the present problems concerning decontamination of large environmental areas
Also read: Confronting Bio-Terrorism: The Anthrax Threat
About the Author
Philip S. Brachman, MD is a Professor in the Rollins School of Public Health at Emory University.