City workers have pulled 9,460 dead pigs from the waterways around Shanghai, the municipal government announced late Sunday.

Authorities have continued to monitor water quality at six drinking water intake points in Songjiang, Jinshan, Minhang and Fengxian districts, according to a report in the Shanghai Evening Post Sunday.

They have not found large-scale infectious diseases among the pig carcasses, nor have they found any sign of zoonosis, which can be transmitted from animals to humans, according to the Xinhua News Agency.

Yu Kangzhen, State chief veterinary officer of the Ministry of Agriculture, said that the government aims to ensure that pigs that die from disease will be disposed of properly and not end up thrown in rivers.

The Shanghai Water Authority did not find viruses in any of the water samples taken from the treatment plants in the districts, and the tap water after being processed was all safe and met national standards, according to the authority's microblog.

The Shanghai Animal Disease Control Center found that 13 of the 20 tissue samples taken from pig carcasses tested positive for porcine circovirus, a virus that does not affect humans.

Meanwhile, the Animal Disease Control Center in Zhejiang Province has found that 16 of the 36 tissue samples it tested contained porcine circovirus. Seven tested positive for porcine epidemic diarrhea virus, another common disease in pigs. Yu said that more pigs have been dying due to poor or overcrowded environments and the cold rainy weather over the winter.

Jinshan district, which is located on the upper reaches of the Huangpu River, was one of the first districts where dead pigs were found floating in the waterways.

"If the dead pigs continue to float here from neighboring Zhejiang Province, we don't know when we will finish removing all of the dead pigs," said Xu Yonghua, vice director of the Shanghai Jinshan District Water Authority.

"We offered workers on the barges an extra 50 yuan ($8) per pig because they have been working overtime to clear the waterway as soon as possible. We are also worried about their health because besides the masks, the safety equipment we have is very basic," Xu said.