WASHINGTON, Dec. 17 (UPI) -- Workers completed fumigating a narrow section of the Hart Senate office building at 3 a.m. Monday but continued disinfecting individual offices during the day to clear them of anthrax spores, Environmental Protection Agency spokeswoman Bonnie Piper said.
It was not clear when the contamination work would be completed and the office might open again, Piper said.
The fumigation work with chlorine dioxide gas covered only the ventilation systems in the building on floors 1 through 9 in the Southeast corner. That section includes the office suite for Senate Majority Leader Tom Daschle, D-S.D., on floors 5 and 6 that was contaminated on Oct. 15 when staff opened an anthrax-laden letter.
Workers are using other methods to continue decontaminating individual offices in the building.
The fumigation work that started Sunday night and ended early Monday was the second round in the Hart building in as many weeks. That work was planned for Friday night, but delayed because the humidity in the building was not at the correct level for the effort. The method calls for a 75 percent humidity level.
The decontamination efforts took on added importance over the weekend when federal health officials suggested workers who were exposed to a large number of spores, such as those in Daschle's office and U.S. Postal Services workers who handled the letter, might still be at risk for inhalation anthrax infection even after taking the recommended 60-day regimen of antibiotics.
The Centers for Disease Control and Prevention in Atlanta this week is expected to recommend to Health and Human Services Secretary Tommy Thompson that Daschle staffers and other at higher risk be allowed to participate in a special program that would make available to them the anthrax vaccine, in three doses, as well as an additional 30-day supply of antibiotics.
Studies on animals have shown even after taking antibiotics for 60 days, some animals develop anthrax infection and die when the medication is stopped, indicating the lungs may retain the spores for longer than 60 days after exposure. Other studies found only animals given the anthrax vaccine and antibiotics were fully protected from lingering spores and any potential new exposure.
Two letters containing a powder anthrax were delivered to Capitol Hill and two others went to media in Florida and New York.
Genetic fingerprinting indicates the anthrax delivered to Capitol Hill are identical to that kept by the U.S. Army for more than two decades, The Washington Post reported Sunday.
Scientists familiar with the most recent tests told the paper although many labs have the Ames strain of anthrax involved in the recent attacks only five have spores with perfect genetic matches to those in the Senate letters.
All those labs can trace back their samples to a single U.S. military source: the U.S. Army Medical Research Institute of Infectious Disease at Fort Detrick, Md., the paper said.
Those matching samples are at Fort Detrick; the Dugway Proving Ground military research facility in Utah; a British military lab called Porton Down; and microbial depositories at Louisiana State University and Northern Arizona University in Flagstaff.
The Post said the FBI's investigation into the anthrax attacks focusing on whether U.S. government bioweapons research programs may have been the source of anthrax used in the attacks. The focus also is on a contractor that worked with the Central Intelligence Agency.
There have been 22 cases of confirmed and suspected anthrax infection, including five deaths from inhalation anthrax, the most serious form of the infection.
