Nan Hanfei was talking about business, and it was news that was helpful to Gu Yanan.

Gu Yanan was grateful, "Every case in the outbreak has helped to identify the source of infection, thank you very much." ”

Nan Hanfei on the other end of the phone smiled slightly, he liked her serious appearance when she worked, and liked to listen to her serious voice.

"Okay, it's good to be helpful, you're busy, if you need my help, call me at any time, 24 hours a day."

Gu Yanan was stunned for a moment before he said "um" softly.

Nan Hanfei didn't say much, and hung up the phone first.

After answering Nan Hanfei's call, Gu Yanan felt strange in his heart, but he couldn't say the specific reason.

Gu Yanan's phone has not been put down, and the email reminds that there is a new email, click on it to see that it is the deceased message sent by Nan Hanfei.

After carefully reading the information of the deceased, the waiter in the food street near Marina View Avenue had a lot of water and food exposure before the onset of the disease, and this case investigation should be representative.

Gu Yanan forwarded the deceased's information to Lu Li, and asked him to arrange for the people from Dongcheng District Disease Control to make further investigations on the seafood restaurant where the deceased was located.

——

Two days later.

Lianhai Center for Disease Control and Prevention, Emergency Office.

Members of the emergency response team reported to Gu Yanan on their work over the past two days.

Mr. Zhou: "In the past two days, Gao Fei and I checked the water quality records of the city and neighboring cities and counties, and also conducted on-site water quality sampling, and the microbial indicators, physical properties and chemical properties and other indicators all met the standards, and the test results of on-site water quality sampling did not find hepatitis A virus. The possibility of hepatitis A outbreak caused by drinking water contamination such as tap water and direct drinking water can be ruled out. ”

Lu Li: "In the past two days, Wang Xiaoxiao and I have followed up the investigation of hepatitis A patients in various counties and districts, and the information has been transmitted to your mailbox, Sister Yanan, in the follow-up process, I noticed that all hepatitis A patients have recently eaten clams, will clams be the source of infection of this hepatitis A epidemic?" ”

Gao Fei asked: "Now is the season for the listing of clams in Lianhai City, as long as you are not allergic to shellfish, you will eat clams a few times, and I have eaten them, so I will be fine." ”

Lu Li asked rhetorically: "How did you eat it?" ”

"The clam soup is white and fresh, and it is better than the clam meat."

Lu Li: "Your approach, the hepatitis A virus can definitely be killed, those hepatitis A patients eat clams with boiling water and eat them, basically eaten raw, at that temperature, the hepatitis A virus in the body of the clams cannot be killed, and those who eat it will be infected with the hepatitis A virus." ”

Wang Xiaoxiao also echoed and said: "Many seafood restaurants cook clams in cold clams, the way to take the clam meat is to boil the water to blanch it, so that the clam meat is half-cooked and tender enough, but the various bacteria and viruses in it can not be killed. ”

Zhou Lao: "In the past, it was reported that mud cockles spread hepatitis A virus, mud cockles are also called mud clams, grow in light cement sand, can enrich the hepatitis A virus in the water, we even eat hairy cockles, also called hairy clams, blood mussels, hairy clams, living in shallow bays and sandy seabed, hairy clams are the same as mud clams, belonging to the mollusk phylum, bivalves, cockles, liver-like digestive gland tissue in the body, with the effect of concentrating and preserving the virus. In the 80s of the last century, there was an outbreak of hepatitis A caused by eating raw clams in Shanghai, and more than 200,000 people were infected. ”

Wang Xiaoxiao felt a burst of creepy, "More than 200,000 people?!" How many people can be affected by a single hepatitis A epidemic? ”

Zhou Lao: "At that time, the samples of hairy clams were not collected in time, and the detection and culture technology of hepatitis A virus was immature at that time, and the identification of the source of infection was repeatedly delayed, resulting in the peak of the second and third waves of hepatitis A, so the total number of cases will be so large." Now that our hepatitis A testing technology is mature, we should be able to find the source of infection quickly. ”

Gu Yanan assigned the task again, "Zhou Lao and Gao Fei went to various seafood markets in areas with a high incidence of hepatitis A to sample clams, and Lu Li and Wang Xiaoxiao investigated the sources of clam supply in each market. ”

——

In the afternoon of the same day, Zhou Lao and Gao Fei collected the test results of clams from various seafood markets, and some commercially available clams were detected with hepatitis A virus.

Lu Li and Wang Xiaoxiao also detected the hepatitis A virus in uneaten clams from the homes of hepatitis A patients.

According to the purchase records of various seafood vendors, the source of the problem clams was quickly found.

The clams containing the hepatitis A virus are all harvested from Haizhou Bay in the eastern part of Lianhai City.

Gu Yanan decided to personally visit the Haizhou Bay Fishing Ground to investigate.

——

In the evening of the same day.

Haizhou Bay Fishing Ground in the east of Lianhai City.

By the time Gu Yanan CDC and his party arrived at the Haizhou Bay Fishing Ground in a CDC on-site flow truck, the sun had already set at sea level, and there was a gorgeous red sunset at the junction of sea and sky in the distance.

Gu Yanan showed his work card, and the fishermen in the fishing ground were very cooperative and took the initiative to introduce the clams fishing process.

According to the fishermen, the fishing area of the problem clam is 12 nautical miles away from the wharf, and the sea depth is more than 10 meters.

There is no possibility of direct contamination by feces during fishing, packaging and transportation by fishermen.

In order to confirm the specific sea area where the problem clams were fished, Gu Yanan called up a map of the offshore sea area from his mobile phone.

Fishermen identified one of these areas: District 8 of the 61st Sea Zone.

Gu Yanan looked at the map and quickly analyzed the possible causes.

The sea area where the problem clam is located is more than 20 nautical miles from the mouth of the Rose River.

It has been reported that at low tide, sewage can be carried into the sea through the tongue of fresh water, extending 120 nautical miles from the coast.

Woolly clams can be contaminated when they grow 10 to 20 nautical miles from the coastline.

The Rose River runs through Lianhai City and is the mother river of Lianhai City, with multiple water quality monitoring points along its banks.

If the upper reaches of the Rose River were polluted, the water quality monitoring points would react, but now the possible cause is the problem between the last monitoring point in the lower reaches of the Rose River and the area where the clams grow.

Knowing that the problem clam sea area may be polluted by sewage brought by the Rose River, the next step is to find the source of the pollution of the river water.

Gu Yanan drove the on-site flow shunting car, carrying the emergency team from the Haizhou Bay Fishing Ground Wharf to the mouth of the Rose River.

By the time we reached the estuary, the sky had completely darkened, the moon had risen, and the vast estuary was surrounded by a large area of tidal flats.

The group parked their cars on the road outside the embankment and stepped up the steps to look around.

On the east side of the embankment is the vast sea, and fishing boats are entering the port one after another.

On the west side of the embankment is the Rose River and the lights of Lianhai City on both sides of the river.

Lu Li looked at the large area of tidal flats at the estuary and sighed, "I heard from friends at the water quality monitoring station that they will sample the water quality of the entire Rose River every month, and they will also collect water from the estuary, and there is no problem every time." ”

Wang Xiaoxiao: "They all come at a fixed time every month, and the sewage containing hepatitis A may be discharged irregularly, and the time of each discharge avoids the water quality monitoring time, so it has not been discovered." ”