Experts reveal why a summer cold is WORSE than a winter one

August 2, 2016  20:41

You might feel hard done by if you’re coughing and snuffling in bed as the rest of the country continues to enjoy the balmy summer weather.

But you’re not alone. Colds are hardly confined to the cold weather, and figures published last week by Public Health England show there has been a rise in the number of people with cold symptoms.

Two outbreaks have been reported in the past two weeks, and there has been an increase among children aged between five and 14 in particular.

The fact is, although we tend to catch more bugs in autumn and winter (as we’re stuck in confined spaces in close proximity to each other), there are still ‘plenty of viruses around in spring and summer’, explains 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, 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 which last 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 — whereas enteroviruses, the ‘summer cold virus’, may also affect the gastrointestinal tract, leading to tummy upset (although this won’t always happen).

Quite why different viruses are more likely to cause colds at different times of year is not clear, though one theory is that some are ‘degraded’ by strong summer sun — summer enteroviruses may be more resistant to UV light. 

Other viruses might survive better in the dry conditions of summer.

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 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’s these chemicals, produced by your own body, that trigger many of the typical cold symptoms, raising your temperature in a bid to kill the virus. 

They also dialte 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 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, to an area known as the olfactory bulb.

The chemicals also trigger sneezing to clear the virus out of your system. Whatever the virus, most of those affected should feel better within a week.

However, Professor Oxford advises anyone with symptoms such as high fever and a rash to see their GP, because enterovirus can rarely 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 the same length of time whatever time of year you catch a cold.’

And muting smells means food tastes bland. Prevention is all about stopping viral transmission in the first place.

‘To wash hands, use soap and water that’s hot to touch,’ suggests 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 telephones.’

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 to ease any aches and pains 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, as your colleagues won’t thank you when they come down with colds just when they are about to go on their annual break.’

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