Acute gastroenteritis due to norovirus (ICD-10-GM A08.1: Acute gastroenteritis due to norovirus) is an infectious disease of the gastrointestinal (GI) tract. Noroviruses are responsible for about one-fifth of all acute gastroenteritis cases. Noroviruses (formerly: Norwalk-like viruses) belong to the family of Caliciviridae along with the sapoviruses. They can be divided into five gene groups (GG I-V), with GG III and GG V being non-human pathogenic.
Norwalk virus, was first characterized morphologically in stool specimens from a 1968 viral gastroenteritis outbreak in Norwalk, Ohio in 1972. The disease was given the name “winter vomiting disease” because of its characteristic symptoms of gushing vomiting and its predominantly seasonal occurrence in the winter months.
Humans currently represent the only relevant reservoir of the pathogen.
Occurrence: The infection occurs worldwide.
Norovirus is highly contagious!
Seasonal accumulation of the disease: An infection with the norovirus can occur at any time of the year, but infections occur more frequently between October and March. Approximately 50% of infections occur between January and March.
Transmission of the pathogen (route of infection) is fecal-oral (infections in which pathogens excreted in feces (fecal) are absorbed through the mouth (oral)), e.g., hand contact with contaminated surfaces, or by ingestion of virus-containing droplets produced during vomiting. Infection can also be transmitted through contaminated food and drink. The possibility of aerogenic infection (droplet infection in the air) has also been demonstrated.
Human-to-human transmission: Yes.
Incubation period (time from infection to onset of illness) is usually 6-50 hours.Duration of illness is usually 1-2 days,
Sex ratio: In children, boys are more commonly affected than girls. In adolescents (14- to 20-year-olds) as well as adults, women are more frequently affected. An exception is the age group of 60 to 69 years.
Peak incidence: The disease occurs predominantly in children under five years of age and adults over 70 years of age.
The incidence (frequency of new cases) is approximately 142 cases per 100,000 population per year.
The duration of infectivity (contagiousness) lasts up to 7-14 days after the end of symptoms (in exceptional cases, however, for weeks).
Course and prognosis: Norovirus infections are usually sudden and severe, but short-lived (1-2 days). The main focus is to compensate for the loss of fluids and electrolytes and to stabilize the energy balance. In severe cases, inpatient treatment is required.
The lethality (mortality related to the total number of people suffering from the disease) is 0.04%, and 81% of the deceased were older than 69 years.
Acute infectious gastroenteritis is reportable under the Infection Control Act in the following circumstances:
- If the ill person is engaged in work as defined in §42 IfSG (Act on the Prevention and Control of Infectious Diseases in Humans),
- If ≥ 2 similar diseases with a suspected epidemiological link,
- Direct detection of norovirus from stool must be reported by laboratories.
