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Inhalational anthrax: What we've learned

By Dr. Sanjay Gupta
CNN Medical Unit

ATLANTA, Georgia (CNN) -- Researchers from the Centers for Disease Control and Prevention say they have learned more about how anthrax disease progresses by studying the bioterror cases seen in the United States in the past month.

The new information means that this flu season, more patients may receive antibiotics and have their blood tested for the presence of bacillus anthracis than ever before.

Between October 4 and November 2, 2001, the first 10 confirmed cases of inhalational anthrax due to intentional release of bacillus anthracis were identified.

Prior to the current outbreak, only 18 cases of inhalational anthrax had been reported in the United States in the past century, most recently in 1976. Those few cases had been associated with exposure to animal products, and along with an outbreak at a military facility in the Soviet Union in 1979, provided the little data scientists previously had on inhalational anthrax.

Now, based on the analysis of the 10 bioterrorism cases, researchers have learned a bit more about the clues that could indicate a patient is infected with anthrax as opposed to some other bacteria or virus.

Researchers have determined that the median incubation period from the time of exposure to the anthrax bacteria to onset of symptoms was four days. On average, the infected patients sought care three and a half days after onset of symptoms.

Experts go on to describe inhalational anthrax as a bi-phasic illness. The first phase, which lasts one to four days, has symptoms very similar to flu: malaise, fatigue, fever, myalgias and non-productive cough.

This is quickly followed by a more severe second stage with respiratory distress, cyanosis (a lack of oxygen that makes the skin turn bluish) and profound sweating. The second phase usually lasts one to two days before death occurs.

Eight of the 10 patients were in the initial phase of illness when they first sought care. Of these eight, six received antibiotics with activity against bacillus anthracis on the same day, and all six survived. The four other patients had more severe symptoms, including one with meningitis, and did not receive appropriate antibiotics until the second stage. All four died. This confirms that early treatment with antibiotics is of paramount importance to the survival of inhalational anthrax.

The chest x-ray also appears to be a sensitive indicator of disease in patients with inhalational anthrax.

None of the 10 patients had an initially normal chest x-ray. There were abnormalities such as widening of the mediastinum, which is located in the middle of the chest, as well as fluid in and around the lungs. These findings are not typically seen with the flu.

Finally, blood tests did show presence of bacteria even before the patients entered phase two of the illness.


• CDC - Emerging Infectious Diseases

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