Noroviruses occur around the world and usually cause gastrointestinal problems. The pathogens are excreted in high numbers in the faeces and vomit of patients and are highly contagious. Therefore, there often are bigger breakouts of diarrhoea and vomiting in community facilities, such as nurseries, schools, seniors' residences or hospitals. Most cases of the disease occur between October and March.
Person-to-person
Noroviruses are usually spread by contact infection from person to person. The pathogens are passed on in minute traces of faecal matter or vomit from patients on the hands. From the hand, the viruses will easily enter the mouth. Tiny virus-containing droplets in the air that occur during vomiting are highly contagious as well.
Via contaminated objects
The pathogens may adhere to objects such as door handles, hand rails or fittings and can easily reach the mouth via the hands.
Via foodstuffs
Raw foods, such as salads, fruit (including frozen berries, for example), crab or shellfish may be contaminated with noroviruses and cause contagion, as well as contaminated water and other beverages.
The disease onset is typically sudden, with severe diarrhoea, nausea and waves of vomiting. Additionally, there is a strong feeling of sickness with stomach and muscle ache, sometimes accompanied by slight fever and headache. The severe vomiting and diarrhoea may quickly cause a lack of fluids in the body, which may become evident by severe weakness or vertigo. The symptoms usually disappear completely after 1 to 2 days.
After infection, disease onset is usually rapid, occurring in a 6- to 48-hour time frame. The patients are highly contagious after they fall ill. Up to about 48 hours after the end of the symptoms, a comparatively large amount of pathogens is excreted in the stool. Patients may excrete viruses and be contagious even for as long as 2 weeks and in exceptional cases even longer, even after vomiting and diarrhoea have ended.
Generally, anyone may catch noroviruses. Children under five and people older than 70 years are affected particularly frequently. They also react particularly sensitively to loss of fluids, which may happen from vomiting and diarrhoea.
Hand hygiene
Always wash your hands carefully with soap and water, especially after going to the toilet and before preparing any food or eating. Then dry your hands carefully using a clean cloth. This prevents pathogens in the intestine from entering the mouth via contaminated hands.
Other hygiene procedures
Correct handling of food
To avoid a possible infection from food contaminated with noroviruses, meals containing seafood in particular should be properly cooked through.
No vaccination against noroviruses has been developed to date.
Your local health authority can provide you with further advice. Since contagious diarrhoea is subject to the rules of the German Prevention of Infection Act, they will also have the latest information and be very experienced in dealing with the disease.
More (specialist) information is also available online from the Robert Koch Institute (www.rki.de/noroviren).
For more information on how hygiene can guard against infection, please visit the Federal Centre for Health Education website (www.infektionsschutz.de).