Symptoms of a mysterious disease that has killed scores of seals off Alaska and infected walruses are now showing up in polar bears, the U.S. Geological Survey (USGS) said on Friday. Nine polar bears from the Beaufort Sea region near Barrow were found with patchy hair loss and oozing sores on their skin, similar to conditions found in diseased seals and walruses, the agency said in a statement. Unlike the sickened seals and walruses, the affected polar bears seem otherwise healthy, said Tony DeGange, chief of the biology office for the USGS\'s Alaska Science Center. There had been no deaths among polar bears, he said. The nine affected bears were among the 33 that biologists have captured and sampled while doing routine studies on the Arctic coastline, DeGange said. Patchy hair loss has been seen before in polar bears, but the high prevalence in those spotted by the researchers and the simultaneous problems in seal and walrus populations elevate the concern, he said. The USGS is coordinating with agencies studying the other animals to investigate whether there is a link, he said. \"There\'s a lot we don\'t know yet, whether we\'re dealing with something that\'s different or something that\'s the same,\" he said. The disease outbreak was first noticed last summer. About 60 seals were found dead and another 75 diseased, according to National Oceanic and Atmospheric Administration (NOAA). Most of the affected seals are ringed seals, but diseased ribbon, bearded and spotted seals were also found. Several walruses in northwestern Alaska were found with the disease, and some of those died as well, according to the U.S. Fish and Wildlife Service. The diseased seals and walruses, many of them juveniles, had labored breathing and lethargy as well as the bleeding sores, according to the experts. The agencies launched an investigation into the cause of the disease, which has also turned up in bordering areas of Canada and Russia. Preliminary studies showed that radiation poisoning is not the cause, temporarily ruling out a theory that the animals were sickened by contamination from the tsunami-wrecked Fukushima nuclear plant in Japan. Spread of the disease among seals continues. A sickened and nearly bald ribbon seal pup was found about a month ago near Yakutat on the Gulf of Alaska coastline, according to the agency. The animal was so sick it had to be euthanized. All of the afflicted species are dependent on Arctic sea ice and considered vulnerable to seasonal ice loss. Polar bears are listed as threatened under the Endangered Species Act, and listings are being considered for the Pacific walrus and for the ringed, bearded and ribbon seals.