Conditions Gastrointestinal infection by noroviruses

Noroviruses cause acute gastrointestinal discomfort, characterized by waves of severe vomiting and bad diarrhea.

The norovirus was originally named after the city of Norwalk in Ohio, where there was a major outbreak at an elementary school in 1968. The term “norovirus” was introduced in 2002.

As the viruses often change their genetic properties, there are many different variants. They are currently divided into 10 main groups. Most infections in Germany are caused by a virus from Group II. 

Noroviruses are the most common cause of gastrointestinal infections in Germany. Children under the age of 5 and older people over the age of 70 are particularly frequently affected.

Noroviruses cause sudden gastrointestinal infections with waves of severe vomiting and bad diarrhea. These symptoms can lead to a dangerous loss of fluids. In some cases, only vomiting or only diarrhea occurs.

People who have a norovirus infection usually feel very sick and weak. Common symptoms are abdominal pain, nausea, and head and muscle aches. The body temperature can be slightly elevated, but high temperatures are rather rare. The symptoms usually go away after one to two days.

In most cases, noroviruses are transmitted from person to person. The viruses are excreted via the stool and vomit. The risk of infection is very high: it is estimated that just 10 to 100 virus particles are enough to infect someone. 

The virus particles can enter the mouth via the hands after touching contaminated surfaces, such as door handles. Infection is also possible via virus-laden droplets produced during vomiting. This high contagiousness is also the reason why noroviruses can spread very quickly in homes for the elderly, hospitals, and community facilities.

But infections can also originate in foods. In particular, raw foods like salads, crabs or mussels, and drinks can be infected with noroviruses.

Norovirus infections are very common. Noroviruses are widespread around the world. Infections can occur throughout the year. They occur frequently between October and March.

The time between becoming infected and the first symptoms occurring is between 6 hours and 2 days. This period of time is known as the incubation period.

While they are acutely ill, infected people are highly contagious. However, the virus can still be excreted via the stool 7 to 14 days, or even weeks in exceptional cases, after an acute illness. So careful toilet and hand hygiene are required even after the symptoms have disappeared.

Hygiene measures can reduce the risk of infection. Frequent hand washing and avoiding contact with infected people is particularly important. Surfaces in the immediate environment of an infected person such as washbasins, door handles, floors and toilets should be cleaned regularly. To avoid infection from contaminated food, seafood dishes in particular should be thoroughly cooked. 

Is there a vaccination against noroviruses? 

Vaccinations are being researched, but no suitable vaccine is yet available.

A stool sample is usually tested to provide evidence of noroviruses. Detection is particularly important when cases occur in communal facilities, hospitals, and nursing homes. In such instances, diagnostic testing should be carried out as quickly as possible. Outside of such facilities, diagnostic testing is not always necessary. However, it should be carried out, for example, in severe cases or for people with pre-existing conditions. 

Confirmed norovirus infections have to be reported to the health authorities. 

There are no medications that act directly on the norovirus. So it is only the symptoms that are treated. As diarrhea and vomiting cause a substantial loss of fluids, this needs to be offset, Therefore, the person affected should drink plenty of fluids. Electrolyte replacement solutions may also be necessary to replace lost salts. Children below the age of 5 and people over the age of 70 react with particular sensitivity to the fluid loss that can occur through vomiting and diarrhea.

In cases of severe vomiting, medications for nausea and the urge to vomit can be taken.

When do medical specialists need to be consulted?

Small children, pregnant women, older adults or people with weakened immune systems in particular receive medical treatment. This is especially true if diarrhea occurs frequently and/or lasts longer than 2 to 3 days and is accompanied by a fever or vomiting.

Sick people should rest and limit contact with others as much as possible. The following should also be observed:

• It is important to drink plenty of fluids when experiencing diarrhea and vomiting.
• To replenish lost electrolytes, electrolyte replacement solutions from a pharmacy or drugstore may help. They contain salts, minerals, and glucose.
• As a general rule, those infected may eat whatever they like and should ensure adequate salt intake.
• If possible, infected people should use a separate toilet for up to two days after recovery. During the illness and in the two weeks that follow, it is important to wash hands with soap and water particularly thoroughly after going to the toilet.
• Vomit or stool residue should be cleaned up as soon as possible as it is highly infectious. The hands should then be washed thoroughly.
• Clothing, bedding, washcloths and towels should be changed regularly and washed at 60 °C.
• The toilet, wash basin, door handles and floors should be cleaned regularly. Single-use cloths are ideal for this purpose. Disposable gloves provide additional protection against infection. Water and standard cleaning materials are normally sufficient. 

What should community facilities look out for?

It is important that the general hygiene rules in community facilities such as homes for the elderly, hospitals, kindergartens, and canteen kitchens are followed properly. To prevent transmission via food, dishes should be thoroughly cooked, in particular those involving seafood.

In community facilities, in particular, whenever there is reason for suspicion, suitable measures should be taken immediately, even if the diagnosis has not yet come back from the laboratory.

The following additional hygiene measures are particularly recommended during the period with diarrhea and vomiting:

• isolation of the people or groups of people who are ill
• wearing gloves, aprons and face masks to prevent infection linked to vomiting 
• good hand hygiene and hand disinfection
• disinfection of surfaces, toilets, wash basins, and door handles in the proximity of patients

Use approved disinfection products which are labeled “begrenzt viruzid PLUS” or “viruzid”.

When can children return to kindergarten?

Children younger than 6 who are ill, or suspected to be ill, with an infection caused by the norovirus should not attend a daycare center or after-school care. This is only permitted 48 hours after the symptoms have cleared up.

Which occupational groups do particular rules apply to?

Anyone who is sick should not go to work in any food-related role, such as in a canteen kitchen. Anyone who works with food may return to work no earlier than two days after symptoms have subsided. Particular attention should be paid to good hand hygiene in the workplace during the following 4 to 6 weeks.