Thursday, 09 December 2021

More viruses to look out for, especially in babies and young children

IT would be easy to overlook the fact that a baby doesn’t breathe while in the womb.

In fact, our lungs are filled with fluid and largely redundant until the moment we are born.

Prior to this, a baby gets its oxygen from its mother’s oxygenated blood via the umbilical cord.

At birth, a baby switches its circulation in a cunning feat of plumbing so that blood no longer flows through the umbilical cord but starts to flow through its lungs instead.

This opens things up, the fluid is pushed out of the lungs and the baby takes its first breath. Pretty impressive. However, it does mean that, for a while, the lungs are a bit vulnerable.

In the first years of life, a baby goes from having around 50 million alveoli (the sacs that provide the surface for oxygen to seep into the bloodstream) to eventually ending up with around 300 million by the time the lungs have finished developing.

Generally speaking, in the first five to eight years of life, the lungs are maturing and expanding. This makes them a breeding ground for all sorts of viruses and results in quite a high incidence of coughs and colds that affect breathing compared with what we have to put up with as adults.

There are lots of different names for conditions that affect a child’s lungs but often they can present in very similar ways, creating a lot of overlap.

Pneumonia is an obvious place to start with it being perhaps the most distinct. Pneumonia is, put simply, a lung infection. It occurs when either a virus or bacteria infects the tissue in the lung and blocks the air exchange surfaces.

Pneumonia is common in all age groups, not just children. But in infants with developing lungs we see other scenarios that don’t happen in adults.

The two most common are what we call viral induced wheeze and bronchiolitis, both of which tend to become more common (the latter especially) over the winter months.

Viral induced wheeze — a term that is refreshingly literal — tends to occur in children between the ages of six months and five years.

About half of all infants have at least one episode in their lifetime but, thankfully, the vast majority of cases do not result in any serious long-term harm.

However, about 15 per cent go on to be diagnosed with asthma if they continue to have episodes beyond the age of five (asthma is not generally diagnosed prior to this as we like to give the lungs a chance).

As the name suggests, a child with a viral-induced wheeze is very wheezy.

The viral culprits are the same ones that cause colds (rhinoviruses and coronaviruses etc). The child may have a fever for a week or so and a cough that could last as long as three weeks but it is self-limiting and often requires no definitive treatment.

The biggest issue with a viral induced wheeze is the wheezing itself. It is important to keep an eye on a child who is wheezing as they may seem perfectly happy in themselves despite deteriorating reserves which, when used up, cause quite a quick deterioration.

Keep an eye on things like respiration rate. If a child is breathing very fast, they should be checked by a doctor. Signs that they are struggling include drawing in their tummy beneath their ribs with each breath or drawing in the chest between the ribs with each breath (known as intercostal recession).

An inhaler might be prescribed in such a scenario but if even this is not helping, then a trip to hospital is not too uncommon for a bit of extra support.

Bronchiolitis is one of the most common lung issues to affect baby and infant lungs. It tends to be more serious and relevant in babies and those below the age of two. Having said that, it is self-limiting and most cases can be cared for at home.

It is thought that around one in three develops it in the first year of life but only about two per cent require admission to hospital.

Bronchiolitis is also caused by a virus, most commonly one called the Respiratory Syncytial Virus that will give an adult a nasty cold.

While this virus inflames only the upper respiratory tract of an adult, infants may develop inflammation in the bronchioles, the smaller branches of the airways at the end of which are the alveoli, hence the name.

The mucus layer of the bronchioles can slough off and cause blockage to some of these airways, creating the need for faster breathing rates and potentially leading to lack of oxygen if severe.

Symptoms of bronchiolitis include a runny nose, a cough, fever and potentially some wheezing too. Babies are prone to dehydration and may have difficulty feeding, not least because their stomachs are right by the lungs and not very big at this stage so any extra volume in this area hampers the breathing process too.

According to figures for England in 2011-12 there were 30,451 admissions to hospital due to bronchiolitis.

As I mentioned, many of the above symptoms could apply to various lower respiratory tract infections but bronchiolitis was identified as a separate entity about 80 years ago. At that time, mortality from the condition was as high as 20 per cent.

Treatment then never reached a true consensus with steam tents, cough mixtures and, more worryingly, doses of aerosol detergents and brandy being used.

After RSV was identified, the subsequent improvement in paediatric intensive care techniques for the more severe cases thankfully reduced mortality and it is about one per cent today. Treatment is largely supportive. Antibiotics are of no use unless there is a secondary infection and are prescribed only if there is a suspicion of this.

The key is to maintain good hydration and oxygen levels until the infection has passed. If it gets to the stage where hospital is required, oxygen therapy can be used and a nasogastric tube is sometimes used to feed a baby.

Since May, there have been a few reported concerns about the numbers of cases we have been seeing and can expect to see in the coming months in the context of the coronavirus pandemic. With less exposure to RSV than usual over the past year, there is some concern that we will now see a spike in cases of RSV bronchiolitis.

Generally speaking, the “season” begins in October and lasts until about March but there have already been some outbreaks, which is earlier than usual. It is important, therefore, that parents know the signs to look out for.

As I said, the vast majority of the time bronchiolitis is self-limiting and gets better on its own. If your baby is off its food, try feeding it little and often rather than in big feeds.

However, if intake reduces to below 50 per cent for a few consecutive feeds, or if nappies become dry for 12 hours or more, the baby needs to be checked by a doctor.

Likewise, get them seen by a doctor if they begin to look tired or drowsy. Bypass your doctor and call 999 instead if there are any really long pauses in breathing or blue lips or if the baby is obviously really struggling to breathe. For milder cases, you can use saline drops to unblock the nose and make it a bit easier to breathe and try to keep your baby upright.

If babies have older siblings that have picked up colds from nursery or school, it might be best to try to minimise exposure and encourage hand washing.

Finally, with any cold-like illness with a cough or fever, remember to think about getting tested for covid. Although covid is generally very mild in babies and infants, it is worth knowing about.

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