A panda research center in northwestern China has been closed to visitors as a precaution to protect the endangered species from catching swine flu, state media reported on Tuesday.
It is not known if pandas can catch swine flu, but there have been reports from veterinary and federal officials in the United States of cats and ferrets catching the disease.
Cold temperatures and heavy snowfall over the last week at the Shaanxi Wild Animal Rescue and Research Center in Shaanxi province have increased flu symptoms and the number of H1N1 cases among zoo employees, the official Xinhua News Agency reported.
The center has stopped recruiting new volunteers and banned employees with flu symptoms from approaching the pandas, it said.
A receptionist who answered the phone at the center, and who refused to give more than her surname Zhou, said all the pandas at the center were healthy, but staff members were taking extra precautions.
There have been no cases of the virus spreading to pandas, Zhou said.
Xinhua said the center, one of four giant panda reserves in China, is home to 21 giant pandas.
The first H1N1 flu death in Shaanxi was reported Nov. 20, and at least 13 other people are critically ill with the virus as of Monday, Xinhua said.
China is moving aggressively to vaccinate vulnerable groups, such as students, with the start of winter and the flu season.
The country has officially reported nearly 70,000 illnesses with 53 deaths from swine flu, but health experts suspect the real number of cases could be higher and say there is little data to prove that steps to stop its spread, such as mass quarantines and school closures, are working.