Two laboratories have been unable to confirm that rabies killed a bear cub that as many as 400 tourists played with at a petting zoo and a barn dance last week.

Initial tests at Iowa State University found that the 5-month-old bear died of rabies on Aug. 27, prompting health officials to try to reach people as far away as Australia to tell them they could be at risk for the fatal disease.

While rabies has not been ruled out as the cause of death, the Iowa Department of Public Health said today that labs at the University of Iowa and at the Centers for Disease Control in Atlanta were unable to replicate the positive test result.

Still, Gary Osweiler, director of Iowa State's veterinary diagnostic laboratory, said the scientists in Ames, Iowa, stand by their work.

"One test resulted not in a strong positive, but in a very weak positive, but it was still judged a positive," Osweiler said. "We did another test Monday, and that also was positive."

Although saliva from the animal must penetrate the skin to transmit the disease, doctors warned that no chances should be taken.

Rick Swenson, who opened the petting zoo on his 250-acre farm in Clermont, Iowa, in June, called the new test results "encouraging news."