WASHINGTON (Reuters) - Experts said on Saturday they were worried by a leaked report that describes an outbreak of smallpox in the Soviet Union -- one they say may point to the testing of a smallpox biological weapon.Seven people became ill in the 1971 outbreak and three died of what appeared to be the more fatal, and more rare, hemorrhagic form of the infection, said Dr. Alan Zelicoff of the Monterey Institute of International Studies, one of the authors of the report."Someone has successfully disseminated smallpox as an aerosol," Zelicoff said in an interview."It has been talked about and it...