XI’AN/CHENGDU — Veterinarians are racing to treat another critically ill giant panda after a measles-like virus recently killed two pandas in captivity in northwest China’s Shaanxi province.

Results of daily medical tests on five-year-old Feng Feng showed serious heart, liver, kidney and lung damage from canine distemper virus (CDV), a highly contagious and fatal disease, according to a spokesman for the Shaanxi provincial wildlife rescue, breeding and research center.

Feng Feng tested positive for CDV on Dec 26 and began to show neurological symptoms on Jan 2. Experts have been conducting antiviral therapy on the animal.

Cheng Cheng and Da Bao, both eight years old and living at the center, died from CDV infection on Dec 9 and Jan 4 respectively, despite efforts to save them. A fourth infected panda, 14-year-old Zhu Zhu, is in stable condition.

CDV, which affects a wide variety of animals, including dogs, primates and large cats, targets the gastrointestinal and respiratory tract, as well as the spinal cord and brain.

Infected animals usually have symptoms such as high fever, eye inflammation, coughing, vomiting, diarrhea, and lethargy. The virus commonly spreads through contact with infected body fluids or contaminated food and water.

Prior to the epidemic, the center was home to 25 giant pandas. After the outbreak, the center sent its healthy pandas to nature reserves elsewhere in the province.

CDV is called the “number one killer of giant pandas.” It is the second time a mass infection has broken out among giant pandas after a previous outbreak in east China’s Nanjing City many years ago, according to Hu Jinchu, a panda researcher.

Giant pandas have a low rate of CDV infection. But once a giant panda is infected, it is difficult to detect early and the fatality rate is high, he said.

Currently, it is extremely difficult to cure the disease, and there have so far been no cases of successful treatment of the disease in giant pandas.

The CDV epidemic in the Shaanxi center has alerted other giant panda breeding centers in China to strengthen preventive measures.

“Some programs that involve close contact between giant pandas and the public have been suspended,” said an official with the Chengdu Research Base of Giant Panda Breeding in southwest China’s Sichuan province, a major habitat for the endangered species.

The Chengdu base has also strengthened disinfection and control of tourists and staff to ensure the safety of the species, said the official.

In addition, the base has started to capture stray dogs and cats and conduct thorough checks on fences, ditches and sewage channels to prevent stray animals from entering the park area.

Giant pandas are one of the world’s most endangered species. About 1,600 of the animals live in the wild, mostly in the mountains of Sichuan, while nearly 400 live in captivity.

The cause of the giant panda epidemic in Shaanxi is unclear.

“CDV infection in giant pandas may be caused by domestic or stray animals,” said Jin Yipeng, a veterinary expert at China Agricultural University.

Nearly 30 domestic leading experts have joined the treatment efforts for CDV-infected giant pandas in Shaanxi, according to Zhang Hemin, director of the China Conservation and Research Center for the Giant Panda.

“To avoid an outbreak of highly contagious diseases among giant pandas, it is urgent to strengthen research on monitoring, prevention and treatment for identified and unidentified diseases in giant pandas and set up special teams and emergency response mechanisms,” he said.