Gu Yanan frowned slightly, "The diarrhea cases in Nanshan Town have been there since the beginning of the month, and now it is the middle of the month, and it has been more than half a month before it was reported to the CDC?" ”

Zhou Lao: "Because there will be cases of diarrhea in this season every year, at first it was only a few cases one after another, until a large number of students in the primary school in the town center were absent from school because of diarrhea, and the local schools and district CDC paid attention to this matter and reported it as an epidemic, and then they began to summarize the recent diarrhea case data, and found that the diarrhea cases have increased significantly since the beginning of this month, so the district CDC suspects that the diarrhea epidemic has begun to emerge since the beginning of the month."

Judging from the symptoms alone, the initial suspicion is that it is bacillary dysentery. ”

Gu Yanan: "What did you find after you and Gao Fei went?" ”

Zhou Lao: "Gao Fei and I first determined the definition of the case, with reference to the international and domestic diagnostic criteria for bacillary dysentery in diarrhea patients, the definition of diarrhea patients in this survey is diarrhea three times a day or more in the past two weeks, or the number of diarrhea does not reach three times a day, but the stool is abnormal, the number of white blood cells or pus cells in the laboratory stool routine examination is greater than 15, and red blood cells can be seen.

After the definition of the case was determined, 159 patients who met the case were initially identified in Nanshan Town through searching.

The diarrhea patients are mainly concentrated in Nanshan Town, so we visited the town hospital and the Yijie Health Center from the first street in the afternoon, and asked the doctor, who reported that there are not many diarrhea cases in this season, but the number of diarrhea cases has increased significantly recently.

According to the internal medicine outpatient register, there were 32 cases of diarrhea patients in the 10 days from the 3rd to the 13th of this month.

With the assistance of the disease control personnel in Xicheng District, the diarrhea patients who were treated at the time were inquired on the spot, contact history, diet, clinical manifestations, and filled in the diarrhea case investigation registration form.

I have sent you an electronic version of the questionnaire, which includes the relationship between diarrhea and diet, precipitation, and drinking water.

Although there are relevant data in the questionnaire, in order to determine the specific route of infection and the cause of infection, statistical analysis is needed, which is inconvenient for me to do, and I have to trouble Director Gu to make statistical analysis overnight, so that we can continue the next step of the investigation.

Tonight, I plan to work overtime with Gao Fei to go to the town center hospital to ask a few more patients, after all, the number of patients in this outbreak is very large, and we need to do a comprehensive investigation. ”

Zhou Lao, Gao Fei and the district disease control personnel were working overtime at the scene, and Gu Yanan could not be idle, preparing to go back to the emergency office now, and statistically analyze the flow data they sent from the scene to determine the transmission route and source of infection.

There are also samples of diarrhea patients sent by the district CDC, and the laboratory should have already produced the results at this time, so we need to urge it again.

Gu Yanan has an epidemic to be busy, Gu Qingcen can only postpone the story to her, Gu Yanan is a little sorry, "Brother Qingcen, I'm sorry, I have to go back to the emergency office to work overtime tonight, the epidemic situation in Nanshan Town is a bit complicated, I have to do some statistical analysis overnight, you tell me the story, we will another day." ”

Gu Qingcen was a little disappointed, but still responded with a smile, "Yanan, you never have to say sorry to me, if you want to say sorry, it's me and I'm not very comfortable, I can't go to the emergency office to help you, I'll talk about the story later, you go and get busy first." ”

——

10:20 p.m.

Lianhai Center for Disease Control and Prevention, Emergency Office.

The results of the laboratory came out, and Shigella dysentery was detected in the samples of diarrhea patients sent by the district CDC, confirming that the outbreak in Nanshan Town was an outbreak of bacterial dysentery caused by Shigella dysentery.

Gu Yanan retrieved the flow survey data sent by Zhou Lao from the email address for statistical analysis of relevant factors.

Outbreaks of intestinal infections are usually caused by eating contaminated food or drinking contaminated water together.

In the preliminary investigation of Nanshan Town, after asking the residents of Nanshan Town, the diarrhea patients had no recent history of eating together, so the food poisoning caused by the common meal was ruled out.

From the statistical analysis of the flow data, it can be seen that the diarrhea is related to eating raw melons and fruits, drinking raw water, and the rainfall at the beginning of this month.

From the analysis of the above series of data, Gu Yanan preliminarily judged that the epidemic was caused by drinking or using contaminated water sources.

As for which water source is contaminated, an in-depth investigation is needed.

Gu Yanan also called up the water supply situation of Nanshan Town from the Internet, and found that the 18 villages and streets in the town are all independently supplied with water supply, all from groundwater, and each has its own water supply system, but there is a Nanxiang River running through the entire Nanshan Town.

Village streets with independent water supply systems, and a large number of diarrhea patients at the same time, then this common denominator falls on the Nanxiang River, which runs through the entire Nanshan town.

Looking at the specific regional distribution of cases, it was found that the incidence rate of cases in each village street was also different, among which the first street had the largest number of cases, and only a few people in several villages located in the upper reaches of the Nanxiang River had the disease, while several villages in the lower reaches of the Nanxiang River, especially the villages adjacent to the first street, had significantly more cases.

And the preliminary judgment is that the first case of this epidemic also appeared in the first street.

Nanxiang River and Yijie are the focus of tomorrow's in-depth investigation.

——

Day 2 morning.

Xicheng District, Lianhai City, Nanshan Town.

Gu Yanan, Lu Li and Wang Xiaoxiao drove the on-site flow shunting of the Municipal Center for Disease Control and Prevention and came to Nanshan Town to meet Zhou Lao and Gao Fei.

In the early hours of last night, Zhou Lao had already received the statistical results of the flow survey data sent by Gu Yanan, and at this time, he was arranging with several people from the district disease control and prevention department to take samples of the water of the Nanxiang River, as well as the investigation of the drinking water sources and suspected contact water sources around the first street.

As soon as the two groups of people met, Zhou Lao immediately reported to Gu Yanan the latest situation last night, "Director Gu, after the investigation in the hospital last night, we found that the first case of this diarrhea epidemic is on the first street, it is Li Xiaole, a third-grade student of Nanshan Town Central Primary School, whose home address is at No. 24 on the first street, and the head of the household, Li Mingfa, is the grandfather of the first case Li Xiaole. ”

"Okay, the information on the flow of the first case is very important, let's go to Li Xiaole's house first to see what we find."

On the first street of Nanshan Town, the home of the first case Li Xiaole.

Li Xiaole's home is a small two-story building, like the neighbor's house, which was self-built a few years ago.

The small building is located on the bank of the Nanxiang River, only a dozen meters away from the waterfront of the Nanxiang River, there is a large courtyard outside the small building, some flowers are planted in the yard, and there are some vegetables and fruits.

Li Xiaole's onset date was earlier this month, and after nearly 10 days of treatment, he has been discharged from the hospital to recuperate at home.

His grandfather, Li Mingfa, developed symptoms on the second day after Li Xiaole's illness, and was discharged from the hospital after treatment, recuperating at home at this time.

The CDC team came to Li Xiaole's house, showed their work permits, and asked about the situation before the onset of the disease.