The Lianhai Municipal Center for Disease Control and Prevention formed an investigation team, led by Liang Lei, as well as two young people from the health department, plus two infectious disease experts from the national disease control - Nan Zhiqiao and Ye Zhenzhen, and a group of five people went to Nanwan Town.

Before going to Nanwan Town, the five of them did a good job of dividing labor, Nan Zhiqiao and Ye Zhenzhen went to the local hospital to investigate whether there were any related cases in recent years, and Liang Lei took two young people from the health department, Xiao Gong and Xiao Zhao, to the home of the confirmed patient to investigate.

A group of five people, because of the different places they went, they took two cars, Nan Zhiqiao drove his own off-road vehicle with Zhen Zhen, Liang Lei took Xiao Gong and Xiao Zhao, drove the official car of the CDC to the scene, and the two cars set off together.

It is a two-hour drive from downtown Lianhai to Nanwan Town, and the two cars drive separately at the fork in the road that is almost close to Nanwan Town.

According to the plan before departure, Nan Zhiqiao and Zhen Zhen went to the Guanhai County People's Hospital to investigate, and Liang Lei's group went to the residential area of Nanwan Town to investigate the patient's residence.

In the Guanhai County People's Hospital, the hospital that received the notice from the Municipal Health and Family Planning Commission in advance prepared the case files of the past years, and Nan Zhiqiao and Zhen Zhen began to check them as soon as they arrived at the hospital.

After checking all the case files for the past three years, they found that cases with symptoms similar to methylmercury poisoning began to appear half a year ago, and there are now a total of 52 similar cases.

Because most of the patients have been discharged home or transferred to another hospital, it is not possible to collect patient specimens, so it is not possible to confirm whether the department is a mercury poisoning patient.

Putting together the 52 case files with similar symptoms, in addition to the similar symptoms, all the files have another similarity - the patients live in South Bay.

Nan Zhiqiao asked Zhen Zhen to write down the addresses of all fifty-two patients, and these were the clues for the next investigation.

After checking the case files with similar symptoms, Nan Zhiqiao asked to check the health status of pregnant women and newborns in Guanhai County in the past three years.

When Nan Zhiqiao asked Liang Lei to contact the local Health and Family Planning Commission, he only said that he wanted to read the cases, and Liang Lei thought that he was only reading the cases related to mercury poisoning, and did not take into account the maternal and newborn parts.

Therefore, this item was not within the scope of advance notice, so Guanhai County People's Hospital did not prepare, Nan Zhiqiao temporarily proposed, and the hospital hurriedly called up the previous maternal and neonatal information.

Ye Zhenzhen understood what Nan Zhiqiao meant, and asked, "Senior Nan, do you suspect that pregnant women in Nanwan Town will also be affected by the mercury poisoning incident. ”

Nan Zhiqiao: "The impact is definitely there, and now I don't know the source of the poisoning, so I can only see the severity of the impact from the previous maternal information." ”

Ye Zhenzhen just checked the literature related to Minamata disease last night and knew that the effect of methylmercury on the fetus is related to maternal intake.

If the maternal intake is very large, the mother itself will develop acute and subacute poisoning, and pregnancy will not be possible.

If the mother's intake is small, pregnancy can be carried but stillbirth or miscarriage is more likely to occur.

If the mother's intake is small, a child with congenital Minamata disease will be born.

If the intake is smaller, the child will be born with only mental retardation and no obvious neurological symptoms.

According to the maternal data of the entire Guanhai County, the stillbirth and miscarriage rates do not fluctuate from year to year.

Nan Zhiqiao frowned, and instructed Ye Zhenzhen: "Take out the information of Nanwan Town separately and analyze it again." ”

Nanwan Township is a small town under Guanhai County, and when analyzing the maternal data of Nanwan Township alone, the number has become smaller, and the results have also changed.

Compared with the maternal data of Nanwan Town in the past three years, the miscarriage rate has increased significantly in the past six months.

Ye Zhenzhen showed the data analysis to Nan Zhiqiao, Nan Zhiqiao frowned slightly, and said, "Let's analyze the situation of newborns in Nanwan Town in the past three years." ”

Recall of neonatal files, there are several common neonatal diseases: neonatal pneumonia, neonatal sepsis, hypoxic-ischemic encephalopathy, purulent meningitis......

There were no major fluctuations in the level of neonatal morbidity in three years.

Ye Zhenzhen read the neonatal case file and summarized and analyzed: "The total neonatal disease rate in Nanwan Town has been stable within three years, there are no children with congenital Minamata disease, and there are two children with mental underdevelopment, but the cause diagnosis is clear, one case is due to intrauterine hypoxia, and the other is because of perinatal brain injury. ”

Nan Zhiqiao: "It seems that the mercury poisoning situation in Nanwan Town has not affected newborn babies, but the increase in maternal miscarriage rates may be related to mercury poisoning. ”

Ye Zhenzhen: "Well, in the case of Minamata disease in Japan, the birth of a child with congenital Minamata disease was two years after the discovery of an adult case, and it takes a process from environmental pollution to the birth of the child.

"Well, so to speak, whether it's direct food poisoning or poisoning caused by environmental pollution, it should be within the last year or two. ”

——

Nan Zhiqiao and Ye Zhenzhen got some clues, and the two returned to the Lianhai City Center for Disease Control and Prevention in the afternoon of the same day with the information they found, focusing on the files of 52 cases with mercury poisoning symptoms.

Liang Lei, Xiao Gong and Xiao Zhao visited the families of confirmed mercury poisoning patients in Nanwan Town, and also found some clues.

Towards the evening of the same day, the two teams met in the conference room on the top floor of the main building of the Lianhai CDC.

Ye Zhenzhen first talked about her discovery in the local Guanhai County People's Hospital.

Liang Lei elaborated on the findings of his group in the patients' homes, "The more than 10 patients with mercury poisoning confirmed in our city hospital, judging from their living locations, all live near the Nanwan River, and they are all in residential areas close to the mouth of the sea. More than 20 family members of the patients developed sensory disorders, with symptoms including numbness around the lips and hands and feet, gloved hands, and socks on bare feet. The sensation of touch, temperature, pain, etc. is reduced. ”

Nan Zhiqiao: "Sensory system disorders are the initial manifestations of mercury poisoning, and this phenomenon can only occur when you are exposed to the same environment. Did you find any suspicious clues in the patient's living environment?"

Liang Lei: "Due to the tight time and the limited sampling tubes, we have only collected specimens from symptomatic family members, and the specimens brought back have been sent to the laboratory department, and the results will be available tomorrow morning." ”

Nan Zhiqiao asked, "Have the environmental samples been collected?"

Liang Lei shook his head, "No." ”

At this time, Xiao Gong from the health department interjected: "Although there was no external environmental sampling, we asked about the diet of the patient's family. ”

Xiao Gong is a tall and thin boy with glasses, who has just graduated and worked for two years, and he knows that there is a collective mercury poisoning incident in Nanwan Town, and he is also busy with the investigation excitedly, especially in front of Nan Zhiqiao, a national expert, and wants to show it.

Nan Zhiqiao followed Xiao Gong's words and asked, "What are the clues on the diet?"