Peking Union Medical College doctor said: Five things you should pay attention to during the peak period of Norovirus infection →

Norovirus can cause acute infectious diarrhea, and the peak period is from October to March of the following year. So, what symptoms will appear after being infected with norovirus? If someone around you is infected with norovirus, how can you protect yourself? How can you tell whether diarrhea is caused by norovirus or other viruses? Today, an expert from the Department of Infectious Diseases at Peking Union Medical College Hospital explains in detail five things you should know about norovirus:

What symptoms will appear after Norovirus infection?

In 1968, a group of students at an elementary school in the town of Norwalk, USA, suffered from an acute gastroenteritis outbreak. The cause was not clear at the time. It was not until 1972 that someone identified the pathogen, an RNA virus, from the feces of the patients at the time. Since the first patient appeared in the town of Norwalk, the virus was named Norwalk virus, also known as Norovirus.

Norovirus infection is common in autumn and winter, usually manifested by nausea, vomiting, abdominal pain and diarrhea. Children are more likely to experience vomiting symptoms, while adults are more likely to experience diarrhea, with feces being watery and without mucus, pus or blood. In addition, fever, headache and muscle pain are also common symptoms, and dehydration may occur due to diarrhea. Of course, some patients may also have mild symptoms or even no clinical manifestations, that is, latent infections.

What is the incubation period and transmission route of Norovirus?

Norovirus has a short incubation period of only 24 to 48 hours and is transmitted through the fecal-oral route, requiring only a very small amount of virus to cause illness. Patients, latently infected persons, and healthy carriers can all become sources of infection.

Norovirus is mainly excreted through the patient's feces, and can also be excreted through vomit. When food and water sources are contaminated by norovirus and ingested by healthy people, it may cause an epidemic. Therefore, norovirus often causes epidemics in places such as schools, nurseries, nursing homes, hospitals, factories and communities.

Someone around you is infected with norovirus

How can I protect myself?

There is currently no vaccine for norovirus infection, so paying attention to personal hygiene and food safety are important means of prevention.

1. Good hand hygiene . Pay attention to hand hygiene at ordinary times. Since alcohol and rinse-free hand sanitizer have no inactivation effect on norovirus, you should use soap and water to wash your hands carefully according to the "seven-step hand washing method". The effective hand washing time should be more than 15 seconds, especially after going to the toilet and changing diapers, to avoid diseases from the mouth.

2. Environmental disinfection . When clustered norovirus infections occur, disinfection should be done properly, using chlorine-containing disinfectants to focus on disinfecting surfaces contaminated by patients’ vomit and excrement.

3. Self-management . If patients have vomiting and diarrhea symptoms and are diagnosed with norovirus infection, they should not insist on going to school or work , especially food workers. Patients should try to use special toilets or toilets, and flush with the toilet lid closed.

Ordinary people should pay attention to their physical health within 48 hours after contact with patients. Once similar symptoms appear, they should go to the hospital for virus screening immediately to avoid infecting more people.

Confirmed patients should be isolated within 72 hours after their symptoms completely disappear. Patients with mild symptoms can be isolated at home, while patients with severe symptoms should be isolated in medical institutions according to the standards for intestinal infectious diseases.

Some students on campus have symptoms such as vomiting.

How should other children be protected?

Many diseases can manifest as vomiting symptoms, so when should we suspect that it is caused by norovirus?

In autumn and winter, when children have symptoms such as diarrhea, loose stools, vomiting, especially when three or more children are sick at the same time , it is necessary to consider that the norovirus is caused. Usually, there will be no special findings in their stool and blood tests. If a diagnosis is required, a pathological test is required.

When norovirus infection is suspected, schools should take the following actions:

1. Students with symptoms are requested to seek medical treatment as soon as possible and be isolated at home under the guidance of a doctor. They can return to school after all symptoms disappear for 3 days;

2. Carry out environmental disinfection, and use chlorine-containing disinfectant to disinfect the surfaces of objects contaminated by the patient's vomit and excrement;

3. Conduct health education: guide teachers and students to perform hand hygiene (running water + soap), and monitor symptoms (diarrhea, vomiting, fever, etc.), report to the doctor in time when symptoms occur, do not drink raw water, and wash vegetables and fruits thoroughly.

If I have symptoms such as diarrhea, am I suffering from Norovirus or some other virus?

Norovirus is an intestinal RNA virus that mainly presents with digestive tract symptoms such as diarrhea and vomiting. The new coronavirus is a respiratory virus that mostly presents with respiratory symptoms such as fever, cough, and sore throat, and diarrhea is relatively mild . In most cases, the two are easy to distinguish. In a few cases where it is difficult to distinguish, it is necessary to collect specimens such as feces, vomitus, and throat swabs for pathological examination to identify them.

Viral infections have some commonalities, such as fever, poor appetite, muscle and joint pain. Generally, white blood cell and inflammatory indicators are not high. Especially for respiratory viruses such as influenza, respiratory syncytial virus, and new coronavirus, it is difficult to distinguish them from the symptoms after infection. For an accurate differential diagnosis, it is still necessary to go to the hospital for pathogen testing to determine the cause and proceed to the next step of treatment.

Author: Liu Xinchao

Assistant Director and Attending Physician of the Department of Infectious Diseases, Peking Union Medical College Hospital. Specialties: diagnosis and treatment of fever of unknown cause, infectious diseases, and HIV.

Audit expert: Li Taisheng

Director of the Department of Infectious Diseases at Peking Union Medical College Hospital, doctoral supervisor, enjoys the special allowance of the State Council. He is currently the chairman of the Infectious Diseases Branch of the Chinese Medical Association. He has been committed to the clinical and translational research of infectious diseases for more than 30 years, and has created a comprehensive diagnosis and treatment model for AIDS suitable for China's national conditions, making important contributions to the clinical diagnosis and treatment of major infectious diseases "AIDS" and "SARS" in my country. During the COVID-19 pandemic, he served as an expert in the National Medical Treatment Group for COVID-19; he was selected as a leading talent in the National High-level Talent Special Program, the first batch of scientific and technological innovation leaders in the National "Ten Thousand Talents Program", and the "2022 Global Top 2% Top Scientists List". He has won the Seville Award of the French Academy of Medical Sciences, the Wu Yang Medical and Pharmacy Award, the National Health and Health Outstanding Contribution Young and Middle-aged Experts, the National Advanced Science and Technology Workers in the Fight against SARS, and the National Advanced Workers. He has published 180 SCI papers, and his papers have been cited more than 10,000 times.

Content from: Liu Xinchao, a doctor at Union Hospital