An education isn't the only thing kids will be gaining when they start the new school term – the far less desirable result of mixing with other children in the classroom is picking up plenty of childhood bugs.
Fortunately, most aren't serious. Nevertheless, they can lead to pupils missing school and parents worrying.
On average, children catch between nine and 12 viruses a year, many during winter, and parents may feel they're constantly unwell.
Reminding them to wash their hands is important but, aside from keeping them in quarantine, avoiding all bugs is practically impossible.
Dr Donald Macgregor, of the Royal College of Paediatrics and Child Health, stresses that nutrition plays a big part, with good levels of vitamin A and E important for protecting the gut and airways.
"Poor nutrition affects the immune system, and children who are better nourished bounce through illnesses much better than children who aren't," he says.
Cough & cold
The rhinovirus (coughs and colds) is the most common type of virus and can be more severe in younger children, as their airways are narrower and their tonsils and adenoids bigger. As they're spread by droplets – coughs, sneezes and on hands – they're far more common in winter when children are huddled together inside, doors shut.
In fact, of the nine to 12 viruses children suffer from each year, eight to ten may occur in four or five months over winter, says Macgregor.
"To some parents, particularly those who've moved to a new area (and 'germ pool'), it feels like their child has a cold or virus all the time," he says. "They're probably right to some extent, as while the virus itself only lasts two or three days, the effects like stuffiness and a cough can last a lot longer. But when a parent thinks a child has had a virus for three or four months, the truth is they've probably had four or five viruses."
Sickness & diarrhoea
Gastroenteritis – inflammation of the stomach and bowel – is often caused by norovirus and rotavirus when it comes to youngsters. Symptoms include vomiting and diarrhoea, usually lasting three to five days, and it can be reduced by encouraging children to wash their hands, says Macgregor, as such bugs are spread through contact.
"We know that the more you wash your hands, the less they spread," he adds.
Chickenpox
The dreaded chickenpox – highly contagious and unmistakable with its itchy rash, starting as small red spots which develop into fluid-filled blisters and eventually scabs. There may be mild flu-like symptoms beforehand too. It's most common in children under ten, and the severity of the rash can range from just a few spots to covering most of the body.
While unsightly and extremely itchy, for most kids it isn't serious, and lots of parents hope to get it out of the way sooner rather than later.
"In pre-school children, chickenpox is a good illness to get because you're immune to it afterwards and it doesn't cause a lot of trouble," says Macgregor.
Mumps, measles & rubella
These highly infectious conditions are usually mild, but can have serious, potentially fatal, complications, including meningitis, swelling of the brain (encephalitis) and deafness.
They can also lead to pregnancy complications, and mumps – characterised by painful swelling at the sides of the face – can spread to the testes in post-pubescent males, which can lead to infertility.
Since the MMR vaccine was introduced in 1988, it's rare for children in the UK to catch the illnesses, although there have been measles outbreaks in recent years. Dr Macgregor urges any parents whose children haven't had the MMR jab to get them vaccinated immediately.
Slapped cheek syndrome
This parvovirus infection can cause mild flu-like symptoms, followed several days later by a bright red rash on both cheeks, which may spread to other parts of the body and cause discomfort and itching.
It can cause problems in pregnancy, but often goes unrecognised in children as it can be very mild and usually doesn't require treatment unless accompanied by a high temperature or symptoms worsen.
Scarlet fever
The bacterial illness, which has reappeared in recent years, can be spread through coughs and sneezes and causes a sore throat, fever and a widespread, fine pink-red rash. It mainly affects children aged two to eight years.
"In years gone by, scarlet fever used to cause dread," says Macgregor. "It's come back but it's probably not as virulent as it was, and there are better treatments."
Head lice
Head lice are extremely common, particularly when children are younger and huddle together more, making it easy for lice to jump from head to head.
The tiny blood-sucking insects, whose eggs are known as nits, can make the scalp inflamed and itchy.
Ian Burgess, director of the Medical Entomology Centre, suggests parents use a good louse comb at least twice a week to comb through hair root to tip. If lice are found, use an approved treatment from a pharmacy and always follow the instructions, as a second treatment is vital.
He says all members of the family should be checked and treated if necessary.
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