February 2025

Summary:

• • • Increase in Norovirus Infections: 3,309 reported cases in Austria in 2024, a significant rise from 2,228 cases in the previous year
    • Genotype Shift: Observed shift from the dominant Norovirus variant GII.4 to GI.17 in Austria and several European countries
    • Rotavirus Vaccination: Oral vaccination reduces hospitalization rates in infants and young children by 60-80%
    • Gastro Panel Diagnostics: Multiplex PCR for simultaneous detection of Norovirus, Rotavirus, Adenovirus, Sapovirus, and Astrovirus
    • New Dashboard: Real-time visualization of GI virus activity on the Institute’s website

Viruses are the most common pathogen group in acute infectious gastroenteritis in Europe. Noroviruses take first place, followed by infections caused by Rotaviruses. Other viral pathogens include Adenoviruses, Astroviruses, and Sapoviruses. 2024 saw a significant increase in Norovirus infections with 3,309 reported cases compared to the previous year with 2,228 recorded cases. During this period, a shift from the dominant Norovirus genotype variant GII.4 to GI.17 was observed in Austria and several European countries.

Fig1: Norovirus infections reported in Austria (from Ref 1)

Outbreaks of Norovirus infections occur frequently in community facilities, partly due to the very low viral load required for infection of only 10-100 infectious particles and significant environmental stability. Enhanced hygiene measures and, if necessary, isolation during outbreaks in healthcare facilities are indicated when suspected. In the absence of specific therapies, medical treatments are limited to compensating for fluid and electrolyte losses.

Rotavirus infections, on the other hand, are the most common cause of diarrheal diseases in infants and young children, sometimes with severe courses. Studies have shown that widespread use of an oral vaccination in the first 6 months of life has reduced the hospitalization rate by 60-80%.

For diagnostic purposes, the Institute of Virology offers a Multiplex PCR from stool samples, the so-called “Gastro Panel”. This enables the detection of the following pathogens in a single reaction: Noroviruses of genogroups I and II, Rotaviruses, Adenoviruses, Sapoviruses, and Astroviruses.

An epidemiological trend of various viral pathogens from our Gastro Panel investigations shows a significant increase in Norovirus activity in 2024 compared to 2023. For real-time visualization of GI virus activity, visit our new dashboard on our website.

For confirmed Noro- and Rotavirus infections, our Institute submits a laboratory report to the EMS (Epidemic Management System). For submissions from inpatient or community facilities, we additionally provide immediate telephone notification of results to support the prompt initiation of hygiene and isolation measures.

Links:

• https://www.ages.at/mensch/krankheit/krankheitserreger-von-a-bis-z/norovirus
• https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2024.29.39.2400625 
• https://www.sozialministerium.at/Themen/Gesundheit/Uebertragbare-Krankheiten/Infektionskrankheiten-A-Z/Rotavirus-(Brechdurchfall).html
• https://publichealth.jhu.edu/sites/default/files/2024-02/rota-brief7-vaccineimpact2022ax.pdf