SHANGHAI, China – More than 2,800 dead pigs were found in a river that supplies water to the city of Shanghai, according to news reports.

The pig carcasses were found in the Huangpu River, a tributary that supplies 23 million residents with most of their drinking water. Shanghai officials said there is no health threat to the city's water, but the incident is being labeled as another example of China's problems with environmental pollution, according to news reports.

Shanghai officials detected porcine circovirus that may have killed the pigs. The sample was taken from a section of the Huangpu River. Bloomberg reported that tests for other diseases such as foot-and-mouth, swine fever, hog cholera and blue-ear came back negative. There is no evidence that porcine circovirus is a safety risk or causes illness in humans, according to the Centers for Disease Control and Prevention in Atlanta.

Porcine Circovirus may cause poor growth and weight loss. Also, pigs can develop enlarged lymph nodes, skin rashes, difficulty breathing, jaundice, fever, stomach ulcers and diarrhea. The virus can cause sudden death. The disease is caused by Porcine Circovirus Type 2, however, not all pigs will show clinical signs of the disease, according to the California Department of Food and Agriculture web site.

China is the world's largest consumer of pork products. The country's pig population is estimated to total more than 400 million animals.