[Smart Farmers] If you have symptoms of vomiting and diarrhea, are you infected with the Norovirus?

The transition from winter to spring is a high incidence period for infectious diseases, and "Norovirus" has become the focus of attention. What symptoms will appear after infection with Norovirus? How can we effectively prevent Norovirus?

When is the peak season for Norovirus?

According to previous epidemiological surveys of norovirus, norovirus outbreaks show obvious seasonality. Winter and spring are the peak seasons for norovirus, with winter slightly higher than spring, and it is even called "winter vomiting disease". Generally, November to April of the following year is the peak season of the year. The epidemic is less prevalent during the winter and summer vacations, and the epidemic quickly rebounds as students return to school.

Norovirus is mainly excreted through the patient's feces and can also be excreted through vomitus. The virus can be excreted from the human body within the incubation period of 12 to 48 hours. The peak period of detoxification is 2 to 5 days after onset of the disease, which lasts for 2 to 4 weeks. The longest detoxification time for patients is even more than 56 days. For immunosuppressed patients, such as those undergoing kidney transplantation, the time is even longer.

How can Norovirus be transmitted?

Norovirus can be transmitted from person to person, through food and through water.

Human-to-human transmission routes include the fecal-oral route, such as inhalation of aerosols from feces or vomitus;

Foodborne transmission includes food contaminated by the virus, contamination by sick catering workers during food preparation and service, and contamination during food production, transportation, and distribution.

Waterborne transmission includes bottled water, municipal water supply, well water and other routes.

Previous studies have shown that human-to-human transmission is the main route of transmission, accounting for more than 60% of norovirus transmission routes, and outbreaks of pure foodborne and waterborne transmission are relatively rare.

What are the symptoms of norovirus infection?

The incubation period after infection with norovirus is 12 to 48 hours, and there are generally no obvious symptoms.

The onset of Norovirus is mainly mild, and common symptoms include diarrhea and vomiting, which accounted for about 60~70% in previous studies. Adults mostly suffer from diarrhea, and children are more likely to have vomiting symptoms than adults.

Secondly, symptoms of infection also include nausea, abdominal pain, headache, fever, chills, muscle aches, etc. The proportion of fever (＞37.3℃) is only about 7~34%.

Although norovirus infection is mainly a self-limiting disease, there are still a few cases that develop into severe illness or even death, accounting for less than 1% overall. Among them, medical institutions have reported a higher risk, and severe illness or death mostly occurs in the elderly and young children.

Are rural residents susceptible to norovirus?

Norovirus is mainly transmitted through clusters, and the main outbreak sites are schools and childcare institutions. The incidence rate from childcare institutions to middle schools is higher than that in universities. It has also occurred in medical institutions, nursing homes, and community institutions.

Due to the relatively low population density, the vast rural areas are less at risk. In previous reports, the outbreak areas were mainly in the southeastern coastal areas, and the incidence rate gradually decreased from south to north.

Despite this, residents in rural areas also need to pay attention to relevant hygiene and disinfection.

Is there a vaccine or specific medicine for norovirus?

Norovirus infection is a self-limiting disease. Currently, there is no specific antiviral drug or vaccine. Treatment is mainly symptomatic and supportive.

During the illness, patients need to pay attention to replenishing water and salt, such as oral rehydration salts, due to diarrhea and vomiting. Symptoms generally last for 2-3 days. Symptoms for people over 85 years old generally last for 4 days, and for immunosuppressed patients generally last for 7 days.

Although there are intestinal flora regulators such as montmorillonite powder and triple live bifidobacterium in clinical research, patients are advised to go to the hospital for evaluation and drug treatment by doctors. Among the drugs currently on the market abroad, only nitazoxanide (NTZ) has completed clinical phase II research. The main research directions of the vaccine for norovirus are virus-like particles (VLP) and P particles.

How can ordinary people, especially those living in rural areas, prevent Norovirus?

Regarding the transmission routes of norovirus, preventive measures include isolating sick people, paying attention to hand hygiene, strengthening environmental disinfection and management of food and water sources.

For sick people, they should be isolated in time from the acute phase of the disease to 72 hours when the symptoms completely disappear, and report to the school, unit and other relevant institutions immediately.

Patients with mild symptoms can be isolated at home or in the institution where the disease occurs. Patients with severe symptoms need to be sent to a medical institution for isolated treatment for intestinal infectious diseases.

Maintaining hand hygiene is the most effective measure to prevent infection and control transmission. You should learn and apply the 6-step hand washing method, washing your hands with soap and running water for at least 20 seconds. Disinfectant wipes and rinse-free hand disinfectants cannot replace standard hand washing.

People living with patients should be careful not to touch ready-to-eat food with their bare hands. At the same time, pay attention to the disinfection of the environment.

What measures can be taken after being infected with norovirus?

When persistent diarrhea or vomiting occurs and Norovirus infection is suspected, the person must be isolated first and report to the school or unit as soon as possible, while paying attention to hydration and fluid replacement.

For cohabitants, the main focus is on hand hygiene and disinfection. 5-6% chlorine-containing disinfectant can be used to disinfect the floor, furniture, etc. Food utensils can be sterilized by steam for more than 30 minutes.

The patient's vomit should be covered and cleaned with 5-6% chlorine-containing disinfectant, and the patient's feces should be covered and flushed with 5-6% chlorine-containing disinfectant.

For bottled water and food that you bring yourself, you need to be careful to avoid contamination, and patients should have separate meals and utensils.

Produced by: Popular Science in China to Benefit Farmers

Producer: Guangming Online Science Department

Planning: Xie Yun, Zhang Mengfan

Review expert: Du Boran, Chief Pharmacist of the Pharmacy Department of Beijing Obstetrics and Gynecology Hospital, Capital Medical University