Norovirus

and Carola Felchner, science journalist

Sophie Matzik is a freelance writer for the medical team.

More about the experts

Carola Felchner is a freelance writer in the medical department and a certified training and nutrition advisor. She worked for various specialist magazines and online portals before becoming a freelance journalist in 2015. Before starting her internship, she studied translation and interpreting in Kempten and Munich.

More about the experts All content is checked by medical journalists.

Norovirus infection is an acute gastrointestinal disease with severe vomiting and diarrhea. It is caused by the norovirus. Infection occurs easily through contact with sick people, contaminated objects or (raw) food. The infection usually only lasts for a few days and subsides again without permanent damage. For small children and the elderly, however, the high fluid loss caused by norovirus can be dangerous. Read everything you need to know about norovirus!

ICD codes for this disease: ICD codes are internationally recognized codes for medical diagnoses. They can be found, for example, in doctor's letters or on certificates of incapacity for work. A08

Noroviruses are highly contagious.Pay attention to particularly careful hygiene and disinfection so as not to infect your relatives.

Dr. med. Mira Seidel

Brief overview: norovirus

Description: a very contagious gastrointestinal disease caused by noroviruses.
High risk of infection: Norovirus is transmitted directly from person to person, via contaminated objects or food, and via droplet infection.
Symptoms: nausea, gushing vomiting, diarrhea, headache, abdominal pain and aching limbs, slight fever, fatigue
Treatment: symptomatic therapy by compensating for the loss of fluids and electrolytes; possibly anti-vomiting agents (anti-emetic); inpatient therapy in the hospital and infusion in severe cases
Prognosis: As a rule, norovirus heals without problems in otherwise healthy adults. Young children and the elderly are more prone to complications from excessive fluid and electrolyte loss.
Notification requirement: Detected infections are notifiable. Suspected norovirus must also be reported in people who work with food or in public facilities.

What is norovirus?

The norovirus is a virus type that is common around the world. It is very resistant to adverse environmental influences: the pathogen survives on food (including chilled ones) as well as on surfaces such as doorknobs, taps, banisters or toilet seats. It can even withstand temperatures of up to 60 degrees for several minutes.

Noroviruses: how to protect yourself

Three questions for

Prof. Dr. Dr. med. Manfred Gross,
Specialist in internal medicine and gastroenterology
1
How dangerous are noroviruses?

Prof. Dr. Dr. med. Manfred Gross
Noroviruses are no more dangerous than other diarrhea pathogens, but they are significantly more contagious than many other germs. A minimal number of viruses is sufficient for an infection. Incidentally, they can also be transmitted through the vomit, which typically occurs at the beginning of a norovirus disease.
2
If I am infected, how do I protect others?

Prof. Dr. Dr. med. Manfred Gross
It is important that you disinfect your hands after using the toilet - with a norovirus-compatible agent. You also need to treat all the surfaces that you touch, so the flushing device and the faucet for example. And: Do not use cutlery or glasses together. After an infection there is no immunity, so you can always get infected with noroviruses.
3
What can I do to avoid getting noroviruses in the first place?

Prof. Dr. Dr. med. Manfred Gross
The best protection against infection with noroviruses is good hygiene with thorough hand washing. So, soap and rinse for at least 30 seconds - and not only after the toilet, but also before you make your meal. When using public toilets, the use of a hand disinfectant solution - which is available in small bottles to take with you - can provide additional protection.
Prof. Dr. Dr. med. Manfred Gross,
Specialist in internal medicine and gastroenterology
Medical Director of the Internal Medicine Clinic Munich South (IKMS) and Chief Physician of the Clinic for General Internal Medicine and Gastroenterology at the IKMS. Since 1999 he has been teaching as an adjunct professor at the Ludwig Maximilians University in Munich.

Attention: Many disinfectants do not work sufficiently against noroviruses. Only preparations with proven effectiveness against viruses (virucidal effectiveness) are suitable.

According to the Robert Koch Institute, noroviruses are responsible for the majority of non-bacterial gastrointestinal infections (medical gastroenteritis). In children they cause around 30 percent and in adults up to 50 percent of all gastroenteritis diseases.

In principle, there is a risk of infection for norovirus all year round. The duration and course of the infection depend on the general health of the patient. Remaining damage after infection with norovirus is unknown.

Norovirus: Routes of Contagion and Protection

Noroviruses are very contagious. Even the smallest amounts of ten to 100 virus particles are enough for a person to develop the norovirus. A single infected person can be enough to cause a local epidemic!

Norovirus - this is how you can prevent it

The norovirus can be transmitted directly from person to person: the vomit and stool of a sick person contain a large number of viruses. Tiny residues of norovirus excretions can be passed on to other people via the hands, for example when shaking hands. If the healthy person then unconsciously grabs his mouth or nose with the hand in question, the viruses can easily penetrate his body through the mucous membranes. This is called the fecal-oral route of infection.

A so-called smear infection via contaminated objects such as doorknobs or cutlery is also possible with norovirus infections. The viruses can even survive for some time on food and in liquids. In the past there have been some local norovirus epidemics that were triggered by contaminated food or drinks (salads, mussels, water, etc.).

In addition, you can also contract norovirus if fine droplets form when vomiting and get into the mouth or nose of another person through the air. This is called droplet infection.

Note: According to the current state of knowledge, the norovirus is only transmitted between humans, but not between humans and animals.

Norovirus: how long are you contagious?

There is a risk of infection immediately after infection with noroviruses (see below: incubation period). It is especially great as soon as symptoms appear. However, patients are contagious for up to 48 hours after the symptoms have subsided. The viruses can even be detected in the stool for up to 14 days, in individual cases even longer. During this whole time, you should therefore pay attention to careful hygiene.

Norovirus: Very often in winter and in community facilities

During the cold season, the immune system is often weak. The mucous membranes are then also less protected against pathogens. Therefore, norovirus outbreaks occur more frequently, especially during the winter months. Cases of illness are also possible for the rest of the year.

The viruses spread particularly quickly where there are many people together in a manageable space. For example, hospitals, community facilities such as old people's homes or nursing homes and schools can become true “norovirus breeding grounds”. Most of the time, such outbreaks can be traced back to inadequate hygiene measures.

Norovirus: How To Protect Yourself

You cannot specifically prevent an infection with the norovirus: there is as yet no norovirus vaccination. However, you can reduce the risk of contracting norovirus with the following measures:

Careful hygiene. Above all, you should wash your hands regularly and thoroughly, especially before eating and after using the toilet.
Disinfect. You can also use a norovirus-effective disinfectant to wash your hands, which is available at the pharmacy. The disinfectant must be left on for 30 seconds to prevent norovirus transmission. All objects that a sick person touches in the household should also be disinfected if possible. These include, for example, door handles, light switches and cutlery. It is best to wear gloves, as surface disinfectants are usually harmful to the skin. A mouthguard is also recommended so as not to inhale virus particles.
To wash. Make sure that laundry that the person concerned has used is always washed immediately. Choose a washing temperature of 90 degrees Celsius to kill any noroviruses that may be present on it.
Avoid contact. Those affected should stay at home for up to two days after the infection so as not to infect other people.

Note: The hygiene measures should be maintained for at least one week after the symptoms have subsided. This is especially true for the conscientious washing and disinfecting of hands.

Many people affected believe that they are immune to infection with the norovirus and thus protected from further illnesses. But this only applies to the exact same virus. However, there are a large number of different subtypes of noroviruses that are also constantly changing. Therefore, there is no immunity to norovirus after an infection has been overcome. The high number of subtypes is also the reason why the pharmaceutical industry is not concerned with the development of a vaccine: It is almost impossible to cover all subtypes with vaccination.

Attention: After surviving the illness, you are not immune to norovirus! The viruses are too versatile for that. An infection with the norovirus can therefore recur at any time, even after an infection has occurred once.

Norovirus: symptoms

The norovirus infection is usually rapid and severe. Most patients experience severe vomiting and diarrhea, usually accompanied by headache, abdominal pain, aching limbs and a slight fever. These acute signs usually last for one to three days. Symptoms such as fatigue and a general feeling of illness can persist for a few days longer.

In individual patients, the norovirus infection only causes diarrhea without vomiting or vomiting without diarrhea. There are also infections that are symptom-free.

Diarrhea and vomiting can cause the body to lose a great deal of fluids and salts (electrolytes). This can be particularly dangerous for young children and the elderly: circulatory problems, seizures and even kidney failure can occur.

You can read everything you need to know about the typical signs of a norovirus infection in the article Norovirus - Symptoms.

Norovirus: incubation period

The norovirus incubation period (infection time) is the time between the norovirus infection and the onset of the first symptoms. It is a little different from person to person. Most patients show their first symptoms just a few hours after being infected. For others, a day or two elapse between infection and the onset of the disease. Overall, the norovirus incubation time can be six to 50 hours.

Caution: Anyone who has become infected with noroviruses is contagious to others during the incubation period - i.e. before the first symptoms appear. The risk of infection becomes even greater with the onset of symptoms.

Norovirus: examinations and diagnosis

If you suspect a norovirus infection, your family doctor is the right person to contact. In order to detect the norovirus, three diagnostic steps are usually necessary: taking the medical history, physical examination and detection of the noroviruses.

Medical history survey

During the so-called anamnesis, the doctor asks about the exact symptoms and other important parameters. Possible questions are:

Do you suffer from diarrhea and vomiting?
Do you feel tired and tired?
What did you eat in the last few hours before the symptoms broke out?
Have you recently been in contact with people who have had similar symptoms?

Even the typical symptoms can be a very strong indication of an infection with noroviruses.

Physical examination

After taking the medical history, the doctor will conduct a physical exam. He puts the focus on the stomach: He first checks with the stethoscope whether normal bowel noises can be heard. Then he carefully feels the stomach. He pays attention to tension ("defensive tension") and possibly painful areas in the stomach.

The physical exam will primarily help rule out other causes of the diarrhea and vomiting.

Detection of noroviruses

There are several diseases out there that cause symptoms similar to those of norovirus infection. A reliable diagnosis is therefore only possible with evidence of the pathogen. To do this, a sample of the stool or vomit is examined in the laboratory. So far, this has only been possible in special laboratories.

Various options are available to detect noroviruses. One can either search for characteristic components of the viruses such as nucleic acids or proteins in the patient samples. Or you can try to detect virus particles directly - with the help of an electron microscope.

Virus detection is important when a given area or community facility experiences a large number of vomiting and diarrhea cases in a short period of time. Once noroviruses have been identified as the cause of the disease, appropriate measures can be taken quickly to prevent the further spread of the pathogen.

Norovirus: mandatory notification

According to the German Infection Protection Act (IfSG), proof of norovirus is notifiable. The data is sent to the responsible health department with the name of the patient.

The mere suspicion of a norovirus infection must be reported if the person concerned is handling food or working in communal catering facilities. The aim of the mandatory notification is to detect local norovirus epidemics at an early stage and thus prevent further diseases.

Norovirus: treatment

There is no specific drug therapy for norovirus infection and is usually not necessary. Instead, you try to alleviate the symptoms as best you can (symptomatic therapy).

In general: Patients with norovirus should take it easy. Bed rest is recommended. Further measures depend on the severity of the symptoms and the general health of the patient.

Norovirus treatment for mild to moderate symptoms

If the infection progresses with only mild to moderate symptoms, the patient can be cared for at home. The loss of fluids and electrolytes (sodium, chloride, potassium, etc.) due to vomiting and diarrhea should be compensated for. To do this, the patient should drink plenty of fluids with sufficient salts. This can be water or tea with a little salt and sugar, broth and diluted juices. In the case of small children and infants, more breast milk or an equivalent substitute must be fed.

Caution: Shifts in the electrolyte values can be dangerous. For example, they can cause drowsiness, circulatory problems and cardiac arrhythmias.

Despite the diarrhea, try to eat a little. This helps the intestinal lining to recover. Rusks, shortbread biscuits and crispbread, for example, are easily digestible. Even after surviving an infection, you should only eat easily digestible food and avoid heavy, high-fat foods.

Note: The home remedy "Cola and pretzel sticks" are not suitable for vomiting and diarrhea: The caffeine in the cola can increase the loss of fluids. That is why cola is not advisable, especially for children. Pretzel sticks are not a problem in themselves. In terms of electrolytes, they primarily supply sodium, but not the potassium that is also required. This is found in bananas, for example.

Norovirus treatment for stronger symptoms

If there are pronounced signs of norovirus, it can make sense to compensate for the loss of fluid and electrolytes with a so-called substitution solution from the pharmacy. This is especially true if the patient cannot or does not want to take in enough fluids and electrolytes. This often happens with children and the elderly.

The substitution solution is also known as oral rehydration solution (ORL) or WHO solution (according to the World Health Organization WHO). It contains glucose and electrolytes such as table salt or potassium chloride dissolved in water. You can get them in the pharmacy, usually in powder form to dissolve in liquid.

In consultation with the doctor, a remedy for nausea and vomiting (anti-emetic) can be administered against severe vomiting.

Norovirus treatment for severe symptoms

If symptoms are severe and persistent, norovirus infection should definitely be treated in hospital. There the doctors can compensate for the loss of fluid with an infusion into the vein. Necessary nutrients and electrolytes can also be administered quickly in this way. Often the patient is also given a remedy for the severe vomiting (antiemetic).

Note: As a rule, children and the elderly are particularly sensitive to the high loss of fluids and electrolytes. For this reason, norovirus therapy is usually carried out in the hospital for them.

Norovirus: pregnancy and young children

Pregnant women are often very worried when they become infected with the norovirus. The noroviruses themselves pose no threat to the unborn child. However, the violent vomiting and / or diarrhea can build up so much pressure in the body that labor starts early. In addition, it is particularly important for expectant mothers that they are always adequately supplied with fluids, electrolytes and nutrients.

When a newborn or infant develops norovirus, it can become very dangerous. Babies and toddlers are sensitive to the virus, and fluid loss can quickly become life-threatening for them. That is why treatment is often given in the hospital.

If an older child or an adult in a household becomes ill with norovirus, special care should be taken with hygiene when dealing with the toddler. The sick person should be isolated from the infant and other family members as much as possible.

Warning: If infants show signs of a norovirus infection, a doctor should be contacted immediately as a precaution.

Norovirus: disease course and prognosis

An infection with the norovirus is usually violent and brief. Symptoms usually last for one to three days. If there are no complications and if the fluid and electrolyte balance is conscientiously balanced, norovirus usually heals without any problems.

Children under the age of six should visit a community facility (such as a kindergarten) no earlier than two days after the (suspected) norovirus infection has subsided. Care must be taken to ensure hygiene.

Especially in people who are older or weakened by other diseases (such as HIV), the norovirus course and the duration of the symptoms can be more severe. This often applies to infants and toddlers as well. Hospital treatment may be necessary here. This is especially true when the loss of fluids and electrolytes is very large. Then there is a risk of internal organs being damaged. Only in very rare cases does norovirus lead to death.

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