In the middle of the winter, norovirus cases in the US have increased significantly according to data from the CDC (US Center for Disease Control and Prevention).

Norovirus, also known as the “vomiting germ”, is spread very easily through contact with contaminated surfaces, food and water, as well as with people who are carriers of the virus.

The first noroviruses were discovered in 1972 – and since then doctors have been finding more and more types of noroviruses, many of which are also transmitted from person to person.

But what is norovirus and how exactly is it transmitted?

Where are noroviruses found?

Noroviruses are present in all regions of the world and are responsible for approximately half of all cases of viral diarrhea.

Most vulnerable to noroviruses are children under five, the elderly and vulnerable groups. Hence, most outbreaks are recorded in nurseries or elderly care facilities.

The more people crowded in one place for long periods of time, the greater the chance of transmission of the virus.

An outbreak of norovirus was recorded at the World Athletics Championships in London, for example, while in 2012 a cruise ship in Germany was quarantined, with 67 tourists – about one in two passengers – falling ill. Last year there was an additional large-scale outbreak in a village in Italy, where hundreds of people required hospital treatment.

Noroviruses grow inside the human body. They multiply in the gastrointestinal tract and are transmitted by droplets, faeces or vomit. In fact, even 10 to 100 particles of the virus are enough to make a perfectly healthy person sick – that is, it is a virus that is transmitted extremely easily: if someone simply touches a door handle that has even a few particles of the virus and then eats something with the same hand, can develop severe symptoms after an incubation period of only 6 to 50 hours.

Can we get addicted to food?

A norovirus can “endure” in a certain environment for a long time – and then return through food to the human stomach.

Thus, one can become infected with norovirus by consuming fruits and vegetables that carry the virus, because, for example, they were grown with manure, or because a farmer simply did not wash his hands properly before picking the fruit. We can also get the virus from eating shellfish from rivers, lagoons or seas into which raw sewage has been pumped.

And most alarming of all: noroviruses can even be transmitted through drinking water if it passes through pipes located near sewers. Frequent interruptions in the water supply and a drop in drinking water pressure can allow contaminated water to mix with drinking water – the same is true, of course, in cases where a cesspool is too close to a drinking water well.

How long do we transmit the virus?

Those who carry the virus can transmit it easily during the period of exacerbation of symptoms (diarrhea and vomiting), but even for two days after symptoms have completely stopped.

After this period strains of the virus are excreted for another two weeks or more. During this time those who come into contact with people who have been infected with the virus must therefore strictly follow the rules of good hygiene.

How is the infection treated?

Doctors can’t do much to treat the virus. If the patient has lost a lot of fluid, a fluid infusion may be necessary, especially in cases of illness in young children or the elderly.

Medicines to treat noroviruses do not exist. Patients should be isolated as much as possible to prevent transmission of the virus, and those caring for the patient should take extra precautions.

How can we protect ourselves?

In addition, there is no vaccine to prevent infection. The only thing that helps is washing and disinfecting our hands and doorknobs or other surfaces we touch frequently – such as keyboards, controls and toilets.

When caregivers come into contact with patients, they must wear gloves, a mask, and special clothing. Dishes and clothes should be washed at a high temperature.

When it comes to food, we have to peel the fruits and cook the vegetables. The following is also beneficial: drink as much lemon juice as possible. Although there is currently insufficient scientific evidence on this, lemon juice appears to be beneficial.

Edited by: Giorgos Passas