Diagnosing Inhalation Anthrax

The sudden appearance of a large number of patients in a city or region with an acute-onset flu-like illness and case fatality rates of 80% or more, with nearly half of all deaths occurring within 24 to 48 hours, may be the first sign of an inhalation anthrax crisis. Rapid diagnostic tests are so sophisticated that they are available only at national reference laboratories.

Once the medical community is on the alert for further cases, the diagnosis would soon become apparent through the recognition of an unusual chest X-ray (a widened mediastinum - heart space) in a previously healthy patient with evidence of overwhelming flu-like illness. These findings will prompt immediate action. Although treating the patient at this stage would be unlikely to save him or her, it may lead to earlier diagnosis in others. Traditional laboratory tests take too long or are not sufficiently diagnostic (until the patient is too far gone) to be of much value.


There is a vaccine available. It has been used most often amongst armed forces personnel. As of March 1, 1999, approximately 590,000 doses had been administered to US Armed Forces, with no known serious adverse events. The vaccine is a 6-dose series. In a study that tested the immunization of monkeys, the vaccine was 100% protective between 8 and 38 weeks, and 88% protective at 100 weeks1.

Current vaccine supplies are limited and production capacity is modest. It may be years before increased production efforts can make sufficient quantities of the vaccine to be available for civilian use. In the event of a biological attack with anthrax, post-exposure vaccination would be recommended. Antibiotic administration (if the vaccine were available) would also be recommended to protect against residual retained spores.


Michael E. Pezim, MD, FRCSC, FACS, DABCRS, in association with Medbroadcast