Introduction

Norovirus (also known as the vomiting bug or the stomach flu) is a highly contagious virus that causes severe symptoms, such as vomiting and diarrhoea. Norovirus is very common and most people have either experienced it or know someone that has. The outbreaks tend to happen in places like restaurants, schools, cruises, and hospitals and are usually caused by contaminated food or poor hygiene. The good news is that we can easily prevent outbreaks from occurring if we follow preventative strategies. These are focused on safety when preparing food. In this article, we will look at how Norovirus is linked to food safety and share some easy ways to help protect you and those around you.

What is norovirus?

Norovirus is a common cause of gastrointestinal illnesses around the world. It was first discovered when an outbreak occurred in 1968 in Norwalk, Ohio, they named it “Norwalk virus” after its location. Norovirus is the most common cause of gastroenteritis in children.¹ Common symptoms of the infection include nausea, stomach cramps, vomiting, and diarrhoea. Other symptoms can include fever and body aches. If you have norovirus illness, due to excessive vomiting and loss of fluids, you may experience dehydration. Symptoms of dehydration are dry mouth and throat, crying with few or no tears, dizziness and decreased urination.²

According to the Centers for Disease Control and Prevention (CDC), each year there are approximately 2,500 reported cases of norovirus outbreaks in the United States. Around 58% of foodborne illnesses are caused by norovirus in the United States. Globally, norovirus causes approximately 685 million cases per year and due to this, an average of 60 billion dollars per year are being used to treat the infection worldwide. Norovirus infections can occur all year round, however, they are more common in the colder months.³

How does norovirus spread?

Norovirus is easily spread (contagious) and spreads quickly through different ways. A person infected will be extremely contagious when they have symptoms, such as vomiting. You will be able to spread norovirus up to 2 weeks after you feel better.⁴

Contaminated food

Norovirus can spread when:

• An infected person touches food with their bare hands
• Food is placed on surfaces contaminated with faeces or vomit particles
• Vomit droplets being sprayed through the air onto food
• Contaminated water being used to grow fruit and vegetables⁴

Contaminated water

Water can get contaminated with norovirus when:

• An infected person vomits or defecates in water
• The water is not treated properly for it to be considered clean, such as with chlorine
• Contaminated leaks into sources of drinking water, such as a well⁴

Contaminated surfaces

Norovirus can spread when:

• An infected person touches a surface with their bare hands
• Objects or food that are contaminated with the virus are placed on surfaces
• The spraying of vomit or splattering of diarrhoea from someone infected onto surfaces⁴

Importance of food safety in preventing norovirus

Contaminated food is one of the main ways norovirus spreads. This can happen through sharing food or utensils with people with the virus. It can also spread whilst preparing food, for example, if they do not wash their hands before preparing food. Hospitals and other care facilities are a common environment for outbreaks to occur. They usually begin with infected staff, patients or visitors and can lead to severe consequences as patients may struggle to fight the infection compared to healthy people. Similarly, schools and cruise ships are common environments where norovirus outbreaks are common, this is due to their close-quarters nature with high-touch surfaces and shared spaces.⁵

When preparing food, especially in restaurants or at catered events, staff must take extra caution when handling leafy greens (like lettuce or spinach), fresh fruits and shellfish (such as oysters), as they are commonly involved in norovirus outbreaks.⁵ Adhering to food practices protects both the individuals preparing the food and the people consuming it and reduces the chance of spreading the virus.

Key food safety practices to prevent norovirus

Several food safety practices can help prevent norovirus outbreaks. These practices should be followed by anyone handling food, even if you’re at home.

Handwashing

You should always practice proper hand hygiene by washing hands thoroughly with soap and water, especially after using the toilet, before eating and before and after handling food.⁶ According to the NHS, you should wash your hands for around 40 seconds and remove all jewellery before doing so.⁷ Alcohol-based hand sanitisers may be used in addition to washing your hands, but should never be used as a substitute. This is because hand sanitisers are not able to kill norovirus. Additionally, it is best practice to wear disposable gloves or use tongs when preparing and handling food, as this can decrease the chance of contaminating the food compared to using bare hands. However, you should still wash your hands before and after the use of the gloves to prevent cross-contamination.⁶

Cleaning and sanitising surfaces

Norovirus can survive on surfaces for days, highlighting the importance of thorough cleaning and sanitising of surfaces in kitchens. Countertops, utensils and chopping boards should be cleaned regularly, however, if someone with norovirus has recently vomited or had diarrhoea, the entire area must be disinfected. To clean surfaces, chlorine bleach solution with a concentration of 1000 to 5000 ppm and other disinfectants deemed effective by the Environmental Protection Agency (EPA) should be used.  It is also important to act fast and clean up any spills or contamination involving bodily fluids as it tend to have large amounts of the virus.⁶

Proper cooking and storage of food

Noroviruses are heat resistant and can survive in temperatures as high as 63°C, therefore it is important to cook food thoroughly, taking extra care of raw meat. It may not be obvious when foods are contaminated with norovirus as they may look, smell and taste the same.

Before preparing and eating your food you should:

• Wash fruits and vegetables with clean water
• Cook shellfish, especially oysters, until the internal temperature reaches a minimum of 63°C
• Keep raw meat and shellfish away from ready-to-eat food, including in the fridge in the shopping basket
• Ensure that food is cooked long enough, for example, quick steaming may not heat food enough to kill the virus
• Throw out contaminated food with norovirus, even if you are unsure⁸

Avoid handling food when sick

Do not prepare or handle food when you are sick and showing symptoms. You must wait until you are 48 hours free of symptoms before you can begin handling food again. This is particularly important when working in restaurants, schools and cruise ships.⁸

Summary

In summary, norovirus is a very contagious virus that spreads quickly through direct contact with someone infected with the virus or indirectly through contaminated food, water, and surfaces. Norovirus is the most common foodborne and gastrointestinal disease, causing huge concerns for hospitals. There are preventative strategies to stop outbreaks by following basic food safety rules, like washing hands, cleaning surfaces, and making sure food is cooked correctly.

By paying attention to food safety, we protect not just ourselves, but the people around us too. Understanding these strategies as well as how the virus spreads can help reduce the number of outbreaks globally. In turn, this will save lives and reduce the burden on hospitals.

FAQs

Can I get norovirus from food that looks and smells normal?

Unfortunately, norovirus-infected food may still look, smell and taste normal. So if you suspect that food is contaminated, even if it looks and smells normal, you should throw it out.

How long does norovirus survive on surfaces?

Norovirus can survive on surfaces for up to 2 weeks.⁹ This highlights the importance of regularly cleaning and disinfecting surfaces to prevent the spread of the illness.

Are hand sanitisers effective against norovirus?

No, hand sanitisers may be used as extra protection after you wash your hands but cannot be used as a substitute, as they do not kill norovirus. Always wash hands with soap and water for at least 40 seconds.

How do I know the food that I have cooked is safe to eat?

Ensure you are cooking food thoroughly and heating it internally to at least 63°C.

What should I do if I think I’ve eaten food that's contaminated?

If you experience severe and prolonged symptoms, such as vomiting, diarrhoea and dehydration, you may want to seek medical attention. However, in many cases, symptoms disappear on their own as your body fights the virus.