A virus that has killed hundreds of pigs in south China has been identified, China's agriculture ministry said Thursday, AFP reported. The virus is probably linked to the reproductive and respiratory condition known as blue-eared pig disease. The ministry warned that the disease would spread rapidly during the summer months, requiring veterinary departments to stay on high alert for the disease. The ministry said the virus could also mutate into a deadlier form if left unchecked. More than 300 pigs in the southern Guangdong province died in April as a result of a secondary bacterial infection of the virus. So far, the disease cannot spread to humans.