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THURSDAY, July 29 (HealthDayNews) -- In the event of a terrorist anthrax attack, knowing quickly who has the disease is critical.

Now doctors may be able to do just that, thanks to a new rapid way of diagnosing inhalational anthrax.

"We identified several clinical characteristics that will help physicians discriminate patients who may have inhalation anthrax from patients who have some run-of-the-mill respiratory infections like pneumonia or influenza," said lead researcher Dr. Demetrios Kyriacou, an associate professor of medicine and preventive medicine from the Northwestern University Feinberg School of Medicine.

To develop the criteria, Kyriacou's team looked at known cases of inhalational anthrax as far back as 1880. In all, they looked at 47 cases of inhalational anthrax, including 11 cases in connection with the still-unsolved anthrax attacks of 2001.

"We compared the clinical characteristics of these cases with 376 patients who had community-acquired pneumonia or influenza-like illness," Kyriacou said.

Some of the factors that distinguish inhalational anthrax from pneumonia or influenza-like illness are nausea, vomiting and mental status changes, according to the research letter in the July 31 issue of The Lancet.

"The one thing that was most predictive of inhalational anthrax was mediastinal widening seen on a chest X-ray," Kyriacou said.

The mediastinum is the space between the lungs. "When that becomes widened, it may be an indication of inhaled anthrax in patients who have fever, cough and other symptoms of a respiratory infection," he explained.

In anthrax, the lymph nodes, which help fight off an infection, become rapidly inflamed and enlarged, causing the mediastinum to widen, Kyriacou added.

Kyriacou believes these clinical predictors may help physicians on the front lines, in their offices or in emergency rooms, to quickly identify patients who might have inhalational anthrax.

"If there is an outbreak of inhalational anthrax as the result of a bioterrorism attack, every minute counts," Kyriacou said. "If we can identify an outbreak early, then we can mitigate the consequences of a bioterrorism attack."

"This is important, because the symptoms of anthrax are nonspecific," said Jeremy Mogridge, an assistant professor of laboratory medicine and pathobiology at the University of Toronto. "It's very difficult to determine whether a person has anthrax."

According to Mogridge, who wrote an accompanying journal editorial, it is important to identify anthrax early, because it is difficult to treat the disease, even with antibiotics, after symptoms have developed.

"The toxin produced by anthrax can kill a person even as antibiotics are fighting the bacteria," he said.

Using these criteria is much faster than waiting for the results of lab tests, Mogridge said.

"Any kind of ability for a physician to distinguish between anthrax and influenza will allow a more effective response," Mogridge said. "In the context of a bioterrorism attack, if there is a large population that has been exposed, there have to be ways of distinguishing people that have anthrax from those with influenza."

Mogridge believes these new criteria should be given to all emergency departments. "Information has to be there on-the-spot so that doctors can make a quick decision," he said.

More information

Get a primer on anthrax from the National Institute of Allergy and Infectious Diseases.

(SOURCES: Demetrios Kyriacou, M.D., Ph.D., associate professor, medicine and preventive medicine, Northwestern University Feinberg School of Medicine, Chicago; Jeremy Mogridge, Ph.D., assistant professor, Department of Laboratory Medicine and Pathobiology, University of Toronto; July 31, 2004, The Lancet)

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