A contagious hog disease in China that last year killed up to a million pigs, and contributed to rising pork prices, has been blamed on the "Blue Ear" virus. Daniel Schearf reports from Beijing.

China's top veterinarian Jia Youling told reporters the highly pathogenic disease, "Blue Ear," is to blame for most of the pig deaths last year. The high fever disease is formally known as Porcine Reproductive and Respiratory Syndrome.

Up to a million pigs died last year from the disease.

Jia says the Blue Ear virus was discovered in the United States in 1987 and has since spread worldwide, posing no threat to humans. But it had mutated in China, making it hard to identify and becoming more deadly to pigs.

"This variation of Blue Ear disease is a completely new variation," said Jia. "It is the first time our country and the world has experienced this kind of the disease."

Chinese health officials are now working on a vaccine to prevent the virus from spreading further.

Jia said their biggest fear is that farmers with sick pigs will try to sell them quickly rather than report the illness. This could cause the disease to spread faster.

Pork prices have already risen dramatically, although Jia said he was not convinced of a direct link between rising prices and the disease.

China's Ministry of Agriculture last week said Blue Ear had already infected nearly 46,000 pigs in the first five months of this year and killed more than 18,000, while spreading to 22 provinces and regions.

The failure to spot and treat the Blue Ear disease outbreak earlier raises new fears about the safety of China's food and drug supply.

The country has had a series of such scandals, including the reported sale of tainted wheat gluten to the United States.

In the past few days, Chinese and foreign media have reported the government has found unsafe dried food, and evidence that some hospitals have used fake blood proteins in intravenous drips to treat patients.