Air Currents Carried Anthrax in Postal Building

CDC says cleaning hose launched germs off sorter

THURSDAY, Dec. 20, 2001 (HealthDayNews) -- Health officials investigating anthrax infections at a Washington, D.C., mail center this fall say a routine blast of compressed air might have inadvertently launched the deadly germs into the air, allowing them to be inhaled by postal workers.

In a report released today, the Centers for Disease Control and Prevention (CDC) says its inquiry into the lung anthrax cases at the Brentwood postal facility -- two of which proved fatal -- shows that bacteria in two letters to U.S. senators were scattered by highly pressurized air used to clean a mail sorter machine.

Dr. Rosemary Sokas, associate director for science at the CDC's National Institute for Occupational Safety and Health (NIOSH), says the forceful sorting process appears to have literally slapped microbes out of the envelopes, and the combination of the cleaning hose and the open building's swirling air currents did the rest.

"There are lots of air currents," says Sokas, speaking to reporters in a teleconference. "When there was air hosing, there was clearly the opportunity to disperse [anthrax spores] widely though the air."

Investigators say the anthrax-bearing letter addressed to Senate Majority Leader Tom Daschle (D-S.D.) arrived late Oct. 11 or early Oct. 12. Bar code tracking shows that the envelope passed through a sorting machine in the government mail section of the Brentwood plant at 7:10 a.m. on the 12th.

That machine was opened an hour or two later and cleaned with an air hose, shooting unknown numbers of anthrax spores not only around the immediate area but into distant corners of the massive facility.

A second letter, addressed to Sen. Patrick Leahy (D-Vt.), that also passed through the same sorter during the same "sort run" was discovered Nov. 17, long after the bioterrorism investigation was under way.

Surface wipes of 114 locations in the mail facility taken 12 days after the Daschle letter was processed turned up anthrax bacteria in eight locations. Four were clustered around the sorting machine, and a fifth sample from an air duct 12 feet above the device also proved positive. The rest were found on machinery in other parts of the building, officials say.

But more sensitive vacuum sampling collected anthrax spores from 27 of 39 sites, or nearly 70 percent, officials say. Wayne Sanderson, chief industrial hygienist at NIOSH, says the vacuum procedure picks up more dust from a much broader area than wiping can cover.

The source of the anthrax, which claimed five lives and sickened as many as 17 others, remains a mystery. However, officials say the strain of microbe used in the bioterrorist attack appears to be domestic in origin and may have been pilfered from a university, government or army lab.

Health officials, concerned that a 60-day course of antibiotics might not block all cases of anthrax, this week announced two ways for people to get extra protection: Take the drugs for 40 more days or continue the drugs and also receive an experimental anthrax vaccine.

However, the government stopped short of urging people to get the shot, which until now has been given only to military personnel. "We have inadequate science upon which to base such a strong recommendation," says CDC director Dr. Jeffrey Koplan, adding that he appreciates that such ambiguity might be "frustrating" for patients.

The government says the two options should be considered by anyone exposed to "very high levels" of anthrax spores. These include people working in Daschle's suite in the Hart Senate Office Building when the tainted letter was opened, those who worked in an office where someone contracted inhalation anthrax, and people who spent time in areas heavily contaminated with anthrax spores.

Although more than three dozen Senate staffers already have elected to receive the vaccine, Koplan says as of Thursday, no postal worker had done so. Anyone who agrees to get the shot will have to fill out a consent form.

The vaccine can cause local irritation, including a persistent lump at the site of the injection, nausea, malaise, aches and rashes, Koplan says. Yet because officials only know about the safety of the vaccine in soldiers, who tend to be young, hale and predominately male, Koplan says adverse reactions in the public might vary.

Those who don't get the vaccine and who terminate their antibiotics after 60 days should monitor themselves closely for signs of infection and seek medical care if any appear, Koplan says.

What To Do

For the latest on anthrax, try the CDC or the Michigan Department of Community Health. And for more information on the anthrax vaccine, check this site from the U.S. military.

The CDC has set up two toll-free numbers offering people exposed to anthrax more information on the vaccine. People who speak English should call (888) 246-2675. Spanish speakers should try (888) 246-2857.

The U.S. Postal Service has these tips for what to do if you think you've received a tainted letter.

SOURCES: Teleconference with Rosemary Sokas, M.D., associate director for science, and Wayne Sanderson, Ph.D., chief industrial hygienist, NIOSH; Jeffrey Koplan, M.D., director, CDC; Dec. 21, 2001, CDC Morbidity and Mortality Weekly Report
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