Norovirus

What is Norovirus?

Norovirus is a highly contagious virus and one of the leading causes of acute gastroenteritis worldwide. It commonly causes sporadic illness and outbreaks in hospitals, residential aged care homes, disability services, primary and community healthcare, early childhood education and care (ECEC) services, schools, cruise ships and other communal settings.¹

Norovirus is a significant healthcare-associated pathogen because it has a very low infectious dose, spreads rapidly from person to person, survives for prolonged periods in the environment, and is shed in large numbers during illness. Early recognition and prompt infection prevention and control (IPC) measures are essential to reduce transmission and minimise service disruption.¹–⁴

Epidemiology

Globally, norovirus causes an estimated 685 million cases of acute gastroenteritis and approximately 200,000 deaths each year, predominantly among vulnerable populations.¹

In Australia, norovirus is one of the leading causes of gastroenteritis outbreaks. Although it occurs year-round, outbreaks are more common during cooler months and frequently affect hospitals, residential aged care homes, disability services and ECEC settings, where close contact and shared environments facilitate rapid transmission.²,³

Norovirus Strains

Noroviruses belong to the Caliciviridae family. Genogroups I (GI) and II (GII) cause almost all human infections, with GII.4 responsible for most healthcare-associated outbreaks. New variants emerge over time; however, clinical presentation, diagnosis, treatment and infection prevention and control (IPC) measures remain the same regardless of the circulating strain.¹,⁶

How is Norovirus Spread?

Norovirus is primarily transmitted via the faecal–oral route through direct contact with an infected person, contaminated hands, food, water, environmental surfaces, shared equipment or contaminated linen. Vomiting can aerosolise viral particles, contaminating nearby surfaces and increasing the risk of indirect transmission.²,⁴,⁶

The incubation period is usually 12–48 hours, with illness lasting 24–72 hours. People are most infectious while symptomatic and during the first 48 hours after symptoms resolve, although viral shedding may continue for several weeks.¹,²,⁶

Signs and Symptoms

Symptoms usually begin suddenly and commonly include:

• Nausea
• Vomiting
• Watery, non-bloody diarrhoea
• Abdominal cramps
• Low-grade fever
• Headache
• Muscle aches
• Malaise

Ddehydration is the most common complication and may be severe in infants, young children, older adults, pregnant women, immunocompromised individuals and those with underlying medical conditions. Illness may be prolonged in immunocompromised people.¹,⁶,⁸

Diagnosis

Diagnosis is usually clinical during outbreaks, based on compatible symptoms and epidemiological links. Laboratory confirmation is recommended during outbreak investigations, severe illness, unusual presentations or when results will influence public health or IPC management. Reverse transcription polymerase chain reaction (RT-PCR) testing of stool specimens is the preferred diagnostic method.²,⁴

Prompt recognition, notification and implementation of IPC measures are critical for effective outbreak management.²–⁴

Prevention

Preventing norovirus transmission requires early recognition of illness, prompt implementation of IPC measures and effective environmental cleaning. In healthcare, Standard Precautions should be used for all individuals, with Contact Precautions for suspected or confirmed cases. Eye protection and a surgical mask should also be considered where there is a risk of exposure to vomit or splashes during care or cleaning.²–⁴

People with suspected or confirmed norovirus should be isolated or excluded from communal activities while symptomatic. In healthcare settings, isolation should continue until at least 48 hours after symptoms resolve. In residential aged care, the Communicable Diseases Network Australia recommends isolation or cohorting for 72 hours after symptoms resolve, where practicable, because viral shedding may continue after recovery.²,³

Healthcare workers, disability support workers, educators, food handlers and other staff should not return to work until at least 48 hours after symptoms resolve. Children attending ECEC services should remain excluded until symptom-free for 48 hours.²,⁵,⁷

Hand hygiene is essential. Although alcohol-based hand rub (ABHR) may be used when hands are visibly clean, soap and water are preferred during norovirus outbreaks because ABHR is less effective against norovirus.²,⁴,⁶

Environmental cleaning is critical because norovirus survives on surfaces. Vomit and faecal spills should be contained immediately, followed by cleaning and disinfection using a Therapeutic Goods Administration (TGA)-approved hospital-grade disinfectant with virucidal activity, or a chlorine-based disinfectant prepared according to the manufacturer’s instructions. Frequently touched surfaces, shared equipment, toys, bathrooms and food preparation areas require increased cleaning during outbreaks. Reusable equipment should be cleaned and disinfected between use, contaminated linen should be handled, bagged and transported to minimise contamination, and waste should be managed in accordance with Standard Precautions and local organisational waste management procedures.²–⁴

Treatment and Management

There is no specific antiviral treatment or licensed vaccine for norovirus. Management is supportive and focuses on maintaining hydration, correcting electrolyte imbalance and relieving symptoms.¹,⁶

Most people recover with rest and adequate oral fluids. Oral rehydration solutions are recommended for people at increased risk of dehydration, while intravenous fluids may be required for severe dehydration or persistent vomiting. Older adults, infants, young children, immunocompromised individuals and those with significant underlying medical conditions should be monitored closely for dehydration and clinical deterioration. Antibiotics are not indicated because norovirus is a viral infection.¹,⁶,⁸

References

1. World Health Organization. Norovirus – Immunizations, vaccines and biologicals [Internet]. Geneva: World Health Organization; 2025 [cited 2026 Aug 5]. Available from: https://www.who.int/teams/immunization-vaccines-and-biologicals/diseases/norovirus
2. Communicable Diseases Network Australia. Norovirus and suspected viral gastroenteritis: CDNA national guidelines for public health units [Internet]. Canberra: Australian Centre for Disease Control; 2025 [cited 2026 Aug 5]. Available from: https://www.cdc.gov.au/resources/publications/cdna-national-guidelines-norovirus-viral-gastroenteritis
3. Australian Commission on Safety and Quality in Health Care. Aged Care Infection Prevention and Control Guide [Internet]. Sydney: Australian Commission on Safety and Quality in Health Care; 2024 [cited 2026 Aug 5]. Available from: https://www.safetyandquality.gov.au/resources/aged-care-infection-prevention-and-control-guide
4. NHMRC. Australian Guidelines for the Prevention and Control of Infection in Healthcare [Internet]. Canberra: NHMRC; 2019 [updated 2024; cited 2026 Aug 5]. Available from: https://www.safetyandquality.gov.au/sites/default/files/2026-05/australian-guidelines-for-the-prevention-and-control-of-infection-in-healthcare.pdf
5. NHMRC. Staying Healthy Guidelines [Internet]. Canberra: NHMRC; 2024 [cited 2026 Aug 5]. Available from: https://www.nhmrc.gov.au/about-us/publications/staying-healthy-guidelines
6. Centers for Disease Control and Prevention. Norovirus [Internet]. Atlanta (GA): Centers for Disease Control and Prevention; 2025 [cited 2026 Aug 5]. Available from: https://www.cdc.gov/norovirus/index.html
7. NHMRC. Norovirus infection fact sheet [Internet]. Canberra: NHMRC; 2024 [cited 2026 Aug 5]. Available from: https://www.nhmrc.gov.au/about-us/publications/staying-healthy-guidelines/fact-sheets/norovirus-infection
8. Healthdirect Australia. Norovirus infection [Internet]. Sydney: Healthdirect Australia; 2025 [cited 2026 Aug 5]. Available from: https://www.healthdirect.gov.au/norovirus-infection