Norovirus infects 2 million Australians a year - what is it, and how can it be avoided?

Noroviruses are a group of viruses that are the leading cause of gastroenteritis, which affects an estimated 685 million people worldwide each year. It is endemic in Australia, with the first confirmed outbreak occurring in 1978, and around 2 million are now infected annually. 

Gastroenteritis caused by norovirus is commonly referred to as ‘stomach flu’, ‘winter vomiting’, ‘gastric flu’, and ‘viral gastro’.

What are the symptoms, and how long do they last?

Symptoms typically begin 24 to 48 hours after infection (but can develop as early as 12 hours). Gastroenteritis starts suddenly with vomiting and diarrhoea. Other symptoms can include fever, headaches, stomach pain, low fever, nausea, muscle ache, and fatigue. 

Dehydration is the main issue, especially for children and the elderly. Liquids and rest are the main cure, and symptoms resolve themselves after one or two days, but some cases can persist.  

Transmission and prevention

Noroviruses are incredibly contagious and spread person-to-person or through contaminated surfaces. People are infectious from the moment they feel ill, and their vomit and faeces can pass on the infection. This includes airborne vomit particles, surfaces contaminated by faecal matter resulting from poor hygiene, and physical contact. Consequently, outbreaks are more common in the winter when people gather together and in semi-closed communities such as nursing homes, military settings, schools, hospitals, and cruise ships.

Those in the food industry need to be aware that it can be passed on by handling food, and dirty water can contaminate drinks and certain foods, such as shellfish. For example, oysters were the cause of the 1978 outbreak and the one in 2013 that affected 525 people.

If someone who handles food is infected, they must stop for at least 48 hours after recovery. Any food they touched while infected should be disposed of immediately. 

The primary prevention is good hygiene. This involves frequent handwashing with soap after toilet visits and before preparing or eating food. An outbreak in Victoria this year was partly blamed on people using hand sanitiser instead of soap, so ensure food handlers are aware of correct washing procedures.

Surfaces, where food is prepared, should be regularly sanitised with a food-grade sanitiser and all fruits and vegetables must be thoroughly washed.

As always, follow your food safety program or ask your food safety consultant, your local EHO or food authority if you have any questions. Norovirus is endemic but can be kept at bay with standard personal and food hygiene procedures.

Written by: Food Safety Select