Hundreds of schools across the US and the UK shut down as norovirus outbreak strikes children… School children complain of vomiting as many hospitalised…” The newspapers made headlines and began sending out hourly reports as increasingly school after school declared closed and hospitals treating norovirus blocked visitors.
Probably one of the biggest outbreaks of this century that has shaken parents and children across continents. The “winter vomiting bug”, as it is popularly known, is not possibly country specific and could strike anywhere. Would it strike elsewhere too?
But what causes the spread of this virus? The schools? the people? the children?
While schools are plagued by cases of absenteeism caused by vomiting among students, what few institutions know and understand are the major causes of such illnesses, and how they can be prevented at the institutional level. Dr Mrigank Warrier takes up the discussion with fellow doctors to profile one such lesser known, but leading cause of vomiting and diarrhoea among children — The Norovirus.
Hark back to your school days. You will surely remember missing a few days of school because of ‘loose motions’, and your parents justifying your absence to your teachers by writing in your school diary/calendar: ‘Was suffering from an upset stomach’. If you are a parent yourself, you have no doubt performed this task for your own child when he or she fell sick.
Diarrhoea and/or vomiting are among the most common causes of school absenteeism. They are the symptoms of a group of illnesses that are clustered by doctors under a common heading: acute gastroenteritis (AGE) — short-term spells of these symptoms that are caused by infections of the digestive tract. From bacteria and fungi to parasites and even stress, AGE has a variety of causes; among the least known are viruses.
It would not be an exaggeration to say that thousands upon thousands of viruses can cause AGE; many are similar to each other and difficult to distinguish. They cannot be differentiated based on symptoms.
Despite the availability of advanced diagnostic tests, they are also notoriously difficult to identify. Since the treatment is often the same for all (no antibiotics, only regular hydration), doctors usually don’t bother trying to zero down on which particular virus caused the illness.
However, it is important to note that there are a few viruses responsible for a majority of the cases. Rotavirus is the leading culprit; but a growing, immensely successful immunisation program under which a vaccine against it is administered to all children, has curbed the havoc wreaked by rotavirus. Which is why it is time to turn our attention to the second most important cause — against which there is no vaccine and hence no protection — noroviruses.
Norovirus and school-children
Noroviruses are a leading cause of non-bacterial AGE outbreaks in all age groups worldwide, and are increasingly recognized as the second most common cause of sporadic AGE in children after rotavirus.
An international study that analysed almost 2,000 cases of childhood diarrhoea found that 11.2% of them were associated with norovirus. A Peruvian study revealed that a whopping 71% of all children up to the age of two years have suffered from a norovirus-associated AGE.
The numbers from India are alarming too. Of 226 stool samples collected from children with AGE in Delhi, 36 revealed noroviruses. About 44% of all suspected cases of non-bacterial AGE in Chennai were found to be caused by norovirus. Another study in Pune, Aurangabad and Nagpur revealed that 55% of all norovirus-associated AGE victims suffered from very severe disease. About 15% of all children hospitalised in Christian Medical College, Vellore for diarrhoea were shedding norovirus.
According to the National Institute of Virology (Pune), norovirus infects 7.5% of all children at least once. The number of cases peaks in winter, because of which it is known as the ‘wintervomiting disease’. In western India, a study revealed spikes in cases during the summer months too.
How do noroviruses spread?
The symptoms of norovirusassociated AGE are diarrhoea, nausea, vomiting, low-grade fever and abdominal cramps. Virus particles are shed in the stools, and to a lesser extent in the vomit of patients. Hence, by coming in contact with contaminated surfaces like toilet seats which transfers the virus from hands to the mouth, and by eating food or drinking water handled by people with improper hand hygiene, norovirus is spread from person to person. Recurrent infections are extremely common.