The trichoderma is a marine lamellibranchial mollusc with a thick shell and protruding vertical lines on the shell like tiles, commonly known as millet "tiles". Mainly produced near Lusi fishing ground in Jiangsu Province. After many analyzes and studies, it is believed that the hairy clams produced by Lusi are contaminated through the following three ways: First, fishermen throw bacterial feces directly into the sea, which is only local pollution and the total amount is small; second, nearby land feces are not treated After it rains, it flows through rivers and then into the sea. According to inspections, there are more than 400,000 toilets in nearby land cities. The feces in these toilets have been initially treated and then discharged into the sea. Third, billions of tons of industrial wastewater and domestic sewage from the Yangtze River enter the sea every year. This This may be the main reason why cockles carry bacteria. Of course, this is also closely related to the living habits of hairy cockroaches. Hairy clams live in sandy sea bottoms with a water depth of 4 to 20 meters and shallow seas with a slight inflow of fresh water. A hairy clam needs to filter about 120 liters of seawater every day to absorb humus and microorganisms to survive. If there are a large number of pathogenic microorganisms and other harmful substances such as halophilic bacteria, dysentery bacilli, and hepatitis A virus in the water, they will be ingested by the clams and accumulate in the liver glands. The way Shanghai residents eat clams gives bacteria and viruses an opportunity to invade the human body.