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　　he United States military now says it might havesent live anthrax to 52 laboratories in the UnitedStates and three other countries. On Wednesday, aPentagon official also said that number could rise.

　　Deputy Defense Secretary Bob Work said a wideinvestigation is continuing. The U.S. National Centersfor Disease Control and the Pentagon are carryingout the investigation.

　　Two of the labs, one in Canada and one in Maryland,have confirmed the presence of live spores in theanthrax they received. The shipments went to 18 U.S. states and to Washington, D.C. SouthKorea and Australia also received shipments, along with Canada.

　　The U.S. military provides anthrax samples to labs for research purposes. But, normally aprocess called irradiation kills the bacterial product. Investigators are trying to learn what wentwrong in the military's irradiation of some of the samples.

　　The Department of Defense first announced the problem shipments a week ago. At that timeofficials thought just nine labs were involved.

　　A serious disease

　　Anthrax is a bacterial disease that can cause several kinds of sickness depending on the methodof infection. For example, breathing anthrax spores can cause severe lung problems. Thedisease can be deadly, but treatments can prevent infection and cure an infected person.

　　Deputy Defense Secretary Bob Work told reporters that "as of this point we see absolutely nodanger to the broader American public."

　　Officials said the only people they consider at possible risk are those who packaged theshipments and those who received them. But the officials say they consider even that possiblerisk extremely low.

　　The bacteria were irradiated at the Dugway army testing center in the western state of Utah.But later testing showed the process failed, and at least some anthrax spores remained alive.

　　Mr. Work said so far there is no evidence that suggests sending live anthrax spores was adeliberate act.

　　Anthrax as biological warfare

　　Some see anthrax as a desirable weapon of biological warfare because the bacteria createtheir own spores. The spores serve as strong, protective containers for the bacteria. Also, theanthrax vaccine is not widely available.

　　Another major anthrax incident happened in 2001, just a week after the September 11terrorist attacks in America. Members of the U.S. Congress and several other organizationsreceived letters containing the bacteria. Five people died of the disease. Seventeen others wereinfected but survived.

　　A federal investigation blamed a high-level bioscientist who worked for the U.S. military. BruceIvins died of an apparent suicide before he was charged with any crime.

　　No confirmations of anthrax infections connected to the recent problem shipments have beenconfirmed. However, several people involved are being treated with preventative medicines. ThePentagon has suspended all transport of the bacteria.

　　Last year, the Centers for Disease Control failed to kill an anthrax supply. The live bacteriawere moved to an area where people were working without protective equipment. No one wasinfected in that incident.

　　Several U.S. lawmakers have expressed concern about the anthrax shipments. North Koreahas sharply criticized the United States military for the incident.

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