Why summer COLDS can be WORSE than winter ones
You might feel hard done by if you’re coughing and sniffling in bed as the rest of the country continues to enjoy the summer weather. But you’re not alone. Colds are hardly confined to chilly times of year, and figures published last week by Public Health England show there has been a rise in the number of people with cold symptoms — with two outbreaks reported in the past two weeks and an increase among children aged between five and 14 in particular.
The fact is, though we tend to catch more bugs in autumn and winter (as we are stuck in confined spaces in close proximity to one another), there are still plenty of viruses around in spring and summer, says John oxford, emeritus professor of virology at Queen Mary, university of London.
Indeed, some cold viruses are especially prevalent in summer — and as well as typical cold symptoms, these bugs may also cause nausea and vomiting.
‘Generally speaking, winter and summer colds are caused by different viruses,’ says Professor oxford. ‘Winter colds are usually caused by rhinoviruses, which are the most common viral infections in humans. Summer colds are more likely to be caused by an enterovirus infection.’
Normally, either type of virus will cause mild cold symptoms that last from a few days to a week at most. However, one major difference is that the ‘winter’ rhinoviruses are usually restricted to the upper respiratory tract — the nose, nasal passages and throat — while enteroviruses, the ‘summer cold virus’, may also affect the gastrointestinal tract, leading to tummy upset (though this won’t always happen). Quite why certain viruses are more likely to cause colds at particular times of year is not clear, though one theory is that some of them are ‘degraded’ by strong sun — summer enteroviruses may be more resistant to uV light.
other viruses might survive better in dry summer conditions.
Lab studies have shown that rhinoviruses grow better at cooler temperatures (below 37c) than enteroviruses.
The rhinoviruses invade the upper respiratory tract and don’t need to survive in the lower airways, where body temperature is higher.
As well as being able to survive the heat, enteroviruses are also better able to withstand higher acidic environments in the stomach, which is how they can spread through to the gut.
And while both types of virus are generally spread through droplets in the air carried on coughing and sneezing, enteroviruses are also transmitted via the stool (and dirty hands) of an infected person.
Children are more likely to pick up colds because they tend to have close physical contact with their peers — adults are usually infected because they are in close contact with younger family members, says Professor oxford.
Many of the worst symptoms are caused by your immune system’s reaction to the virus.
During the first few days of a cold, you are very unlikely to know you have been infected. But as the virus replicates, your body steps in, releasing immune cells and chemicals to kill it off.
It is these chemicals, produced by your own body, that trigger many of the typical cold symptoms, raising your temperature in an effort to kill the virus.
They also dilate the blood vessels to allow immune cells to travel swiftly to the affected areas — this causes swelling, which blocks your nose and congests the lungs.
The reason why colds affect your sense of smell is because upper respiratory infections block the passage of odour molecules from the nose to receptors in the brain, in an area known as the olfactory bulb, and muting smells means your food tastes bland.
The body’s chemicals also trigger sneezing to clear the virus out of your system.
The intensity of the body’s virus- attacking mechanism varies from one person to the next, so no two people will react to a cold virus in the same way.
Genetic factors also play a part — you might have an inherited gene that triggers high body temperatures or intense sneezing, for instance.
And gender also has a role. Research from Queen Mary university of London found that men tend to react more strongly than women to the same virus.
Whatever the virus, most of those affected should feel better within a week.
But Professor oxford advises anyone with symptoms such as high fever and a rash to see their GP because in rare cases enterovirus can lead to more serious complications, such as viral meningitis (the less dangerous
form, though still potentially serious) and sepsis. Enteroviruses are a major cause of sepsis in infants admitted to hospital.
‘Because enterovirus can lead to very serious complications and cause stomach and gut problems, summer colds can be worse than winter colds for some people,’ he says. ‘However, in general, symptoms are similar and tend to last for about as long whatever time of year you catch a cold.’
Prevention of colds is all about stopping viral transmission in the first place.
‘ To wash your hands, use soap and water that is hot to touch,’ says Paul Griffiths, a professor of virology at university College London.
‘And it might help to clean things you touch regularly, such as door knobs and phones.’
Enteroviruses and rhinoviruses can be destroyed by contact with a weak solution of bleach.
If your child has symptoms, keep them away from other children and help them maintain good hygiene practices.
Give them plenty of fluids and paracetamol and they should make a fast recovery.
Professor oxford thinks that adults should take sick leave while symptoms are obvious.
‘Don’t go to work if you are coughing and sneezing all over the place, because your colleagues won’t thank you when they come down with colds just when they are about to go on their annual break.’
THEgood news is that summer cold epidemics are less frequent in adults, who have usually built up immunity to them during their childhood.
‘ There are many different kinds, but you only need to be exposed to a few of them before you get immunity across several,’ says Professor Griffiths.
But perhaps it isn’t a cold you have after all.
Many people who think they have one may have hay fever or an allergy, and vice versa, says Dr Imran Rafi, chair of clinical innovation and research at the Royal College of GPs.
‘It can be easy to confuse the two, especially if hay fever exacerbates asthmatic coughing.
‘But mucus caused by hay fever is usually clear, not yellow or green, which reveals the presence of white blood cells fighting infection. Hay fever is often accompanied by itchy eyes and throat.’