More than 257,000 pigs had been infected with the epidemic, known as blue-eared pig disease, by late August, with 68,000 of them dying, official Xinhua news agency said late Saturday.
Experts quoted in the Western media have expressed doubts about the official figures, suspecting the government is trying to keep a lid on a more serious crisis.
Xinhua quoted a top official as saying more than 100 million pigs had been immunised, but that control efforts faced severe challenges.
"The disease control situation remained grim because the breeding methods in some regions lag behind other regions and long-distance pig deliveries were adding to the hidden trouble," it quoted Vice Agriculture Minister Yin Chengjie as saying.
He said the situation was exacerbated in the vast Yangtze River basin by a warm and wet summer, which has created conditions conducive to spreading the disease, also known as porcine reproductive and respiratory syndrome.
China will increase monthly production of a vaccine for the disease to 300,000 litres (79,000 gallons) in September, up from a previous 250,000, Yin told Xinhua.
The spread of the disease, which first appeared earlier this year, has emerged as a major health concern for the government and has been blamed for contributing to a sharp spike in prices of pork, a staple of the Chinese diet.