This post is by regular contributor Naomi Cook.
Gastro is my true Nemesis. Give me seven days of cold or flu over 24 hours of gastro! We all dread the emails alerting us to a new gastro outbreak at school or kindy. Then (usually in the cold dead of the night), follow the buckets, tissues, disinfectant, stained sheets and duvets and the sleep deprivation. Not content to stop at one, this miserable virus then usually makes its way through the family, claiming all, one by one…
I wanted to do this important topic justice so have split this information into two posts. Today I will focus on Norovirus and how infectious it really is; ways it is spread; symptoms; illness duration and recommendations for school and work.
What is Norovirus?
It is estimated that in developed countries around 20-25% of the population experience an annual bout of gastro. 4 Norovirus is frequently to blame for community based gastroenteritis. 4
- Norovirus is highly contagious. 9 The amount of virus needed to transmit infection is tiny. 1,4 You need 10-100 virus particles to get sick,9 but each ml of vomit can contain a million virus particles! 13
- At least 50% of those exposed to the virus will go on to develop symptoms. 7,9
- Unluckily for us this virus is pretty robust and has great environmental stability. 4 It can survive drying, heating to 60 degrees, freezing and will also withstand some levels of chlorine in water. 9
- Norovirus usually occurs in families and due to its high infectivity can tear its way through communities, especially daycare centres and schools. 1,6
- Childhood infection is not protective of infection in adulthood. 9 This means we can get infected again…and again…and again.
How do we catch it?
- Directly via the “Faecal Oral” Route: This basically means particles of virus from contaminated poo and vomit reach the mouth of the host (usually via the hands) and enter there. 1,4,6 This can be thorough direct contact with these bodily substances but can also be indirect (see below).
- From the Air: Norovirus has also been shown to spread through aerolised particles when vomiting occurs. 1,4 The tiny pieces of virus enter the new host mouth through a spray and then are swallowed. A large group of patrons at a restaurant were all infected this way, bon appetite! 5
- The Indirect “Faecal Oral” Route: Aerolised particles from toilets flushing or from a vomit land on surfaces that hands then touch such as toilet seats, flush buttons, toilet door handles and so on. 1 Other common surfaces that act as norovirus waiting rooms are taps, telephones, door handles and liquid soap dispensers. 1 Virus may have been transferred to these places by contaminated hands.
- Through infected food and water7 Norovirus is the most common cause of food born viral gastroenteritis. 10 Common sources of water transmission include tap water, swimming pool water, lakes 7 and outbreaks have even occurred via water fountains in children’s play areas. 3
Did you know?
- There have been incidents recorded of people being infected from a previously contaminated area up to 13 days after a gastro incident has occurred. 2
- Contaminated fingers have been shown to infect up to 7 surfaces touched sequentially. 1
- In addition, 14 people can be contaminated one after another after touching the same infective surface! 1
- Usually a sudden onset of vomiting 4 and or diarrhoea 9
- Vomiting may be profuse
- Vomiting tends to occur in the first 24 hours and is then followed by diarrhoea for the rest of the illness 4,8
- A low grade fever may be present 15
- Stomach cramps 15
- Muscle aches 15
How long will it last?
- The incubation period (from when you contract the virus to when symptoms start) is usually 24-48 hours but can be in the 12-72 hour range. 15 Knowing this helps to pinpoint where/who you caught it from.
- The illness usually lasts from 1-3 days. 6
- Very young children, especially those under two, may suffer for up to seven days. 6
How long should we stay away from school, work and food preparation?
- Public Health policy in Western Australia and Queensland states that children and adults should not return to daycare, school or work until 24 hours have passed since the last symptom experienced. 13, 14 This means those affected by ongoing diarrhoea should stay at home, then after the last bout of diarrhoea occurs wait the prescribed hours before returning to work/school.
- In Queensland, food handlers and day care teachers are required to wait 48 hours 13
- NSW states a general 48 hour waiting period 12
- UK Policy is 48 hours 16
- US Policy appears to be 48-72 hours 10 (this reference is a really interesting case report of a food handler passing on the virus to 100 people through chopping a lettuce!). The CDC state that people are still infectious for at least three days post infection onset 11
After this period, althoug symptoms have cleared, there still may be viral shedding (in faeces) for some time. This means the infected person may still have the capacity to pass on the virus during this time. Studies have shown viral shedding in faeces from two 6, 9 to as much as six weeks 6 post acute infection. Interestingly, the prolonged viral shedding is more common in babies. 6
Notification is Very Important 15
- If your children have recently had an episode of gastro, it is necessary to notify people in contact with your children who may deal with nappy changing, bottom wiping and toilet flushing in the weeks post infection.
- It would be considerate to notify any friends planning play dates at your house if anyone in the household has recently had gastro. In addition, you should avoid sharing your own food/snacks with others on playdates outside the home.
- Gastro Outbreaks must be notified. This means that your local Public Health Unit needs to be alerted if an outbreak is suspected (not necessarily confirmed).15 Two or more related cases in a 24 hour period is considered an outbreak.
- If you or your children are sick, it is important to ask around your local community (i.e at day care, school, work, or any extra curricular activities) to not only determine the source of infection but also to see if others have been ill. Reference 3 is a great example of why this is important. If there are more cases you can ring to notify your local Public Health Unit, or notify your local GP/Practice Nurse and ask them to do the same.
Click through for Part 2: Prevention, Treatment and The Gastro Survival Pack
How (un)lucky have you been this season with gastro?
DISCLAIMER: The information contained in this article should NEVER be used as a substitute for the advice of a licensed physician. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please see a physician if you think you or your child are unwell.
- Barker J, Vipondb I, Bloomfiled S. (2004) Effects of cleaning and disinfection in reducing the spread of Norovirus contamination via environmental surfaces. Journal of Hospital Infection 58, 42–49
- Chessbrough J, Barkiss-Jones L, Brown D. (1997) Possible prolonged environmental survival of small round structured viruses. Journal Hospital Infections 35:325—326
- Hoebe C, Vennema H, Husman A, Duynhoven Y. (2004) Norovirus Outbreak among Primary school children who had played in a water fountain. Journal of Infectious Diseases 189:15 pp699-705
- Lopman B, Reacher M, Vipond I, Sarangi J, Brown D. (2004) Clinical Manifestation of Norovirus Gastroenteritis in Health Care Settings. Clinical Infectious Diseases 39:318–24
- Marks P, Vipond I, Carlisle D, Deakin D, Fey R, Caul E. (2000) Evidence for airborne transmission of Norwalk-like virus (NLV) in a hotel restaurant. Epidemiolg Infect 124: 481—487
- Murata T, Katsushima N, Mizuta K, Muraki Y, Hongo S, Matsuzaki Y. (2007) Prolonged Norovirus Shedding in Infants 6 Months of Age With Gastroenteritis. The Pediatric Infectious Disease Journal 26:1 pp46-49
- Nygard K, Torven M, Ancker C, Knauth S, Hedlund K, Giesecke J, Andersson Y, Svensson L. (2003) Emerging Genotype (GGIIb) of Norovirus in Drinking Water, Sweden Emerging Infectious Diseases 9(12): 1548–1552
- Rockx B, de Wit M, Vennema H, et al. (2002) Natural history of humancalicivirus infection: a prospective cohort study. Clinical Infectious Diseases 35:246–53
- Simon A, Schildgen O, Binger A, Hasan C, Bode U, Buderus S, Engelhart S, Fleischhack G. (2006) Norovirus outbreak in a pediatric oncology unit Scandinavian Journal of Gastroenterology 41: 693-699
- Multisite Outbreak of Norovirus Associated with a Franchise Restaurant, MMWR
- Norovirus Illness: Key Facts, Centers for Disease Control and Prevention
- Norovirus, NSW Health
- Viral Gastroenteritis, Queensland Health
- Norovirus Infection Fact Sheet, Public Health, Department of Health, Government of Western Australia
- Recent Norovirus Gastroenteritis Activity, NSW Health
- Norovirus, Public Health, Wales