A photo taken on Feb 23, 2006 depicts a veterinarian from Wuhan Zoo vaccinating a panda against canine distemper. [Photo/CFP]

A fourth panda has died of canine distemper at Shaanxi Rare Wildlife Rescue and Breeding Research Center in Xi’an, the capital of Shaanxi province, adding to the death toll caused by the disease since Dec 9, 2014.

The panda named Feng Feng, which was diagnosed with the infection on Dec 26, had received emergency treatment for more than one month by 30 experts from all over the country, but it finally died of organ failure and breathing difficulties on Feb 4.

According to Han Xueli, general office director of Shaanxi Rare Wildlife Rescue and Breeding Research Center, the 5-year-old Feng Feng was the youngest among the four dead pandas and had fought against the disease for the longest time.

The other three pandas died of distemper respectively on Dec 9, Jan 4 and Jan 23 after days of treatment, Han said.

Canine distemper, which hit the center in December, is a highly contagious virus that mainly infects canines and felines. The mortality rate can be up to 80 percent.

After the epidemic hit it, the center followed its emergency plan for disease control and prevention immediately with such measures as keeping the animals in separate rooms with a staff member assigned to care for each of them, and applying high-strength disinfectant over the entire center, Han said.

Besides the four dead pandas, another one was diagnosed and three more are suspected of being infected..

The blood tests showed negative for the disease for the panda named Zhu Zhu which was also diagnosed with distemper and other three which were suspected to be infected with the disease.

The panda treatment experts said that these results confirmed that they were in stable condition. "We cannot yet say that the four pandas diagnosed and suspected with the disease have fully recovered, and intensive care and continuous treatment should be given them in the following days," treatment experts said.

The center housed 25 pandas before the epidemic.