Parainfluenza virus: infections, croup and what to do

Parainfluenza viruses are respiratory viruses that infect the nose, throat and airways. UK Government guidance on outbreaks of acute respiratory infection in care homes names parainfluenza among the non-influenza viruses, with respiratory syncytial virus, rhinovirus, adenovirus and human metapneumovirus, that commonly cause outbreaks. These tend to be seasonal, peaking between autumn and spring.

In everyday UK health information the virus is mostly discussed because of croup. NHS inform says commonly croup is caused by a virus and that in most cases it is the parainfluenza virus. NICE CKS adds that croup is typically caused by parainfluenza virus types 1 or 3. The sources read for this guide focus on childhood croup rather than on adult infections or other illnesses caused by the virus.

The NHS lists the main symptoms of croup as a barking cough that may sound like a seal, a hoarse voice, difficulty breathing and a high-pitched, rasping sound when breathing in. Children usually have cold-like symptoms first, such as a temperature, runny nose and cough, and croup symptoms usually come on after a few days and are often worse at night.

NHS inform describes the harsh breathing-in sound as stridor, which is often most noticeable when the child cries or coughs. Croup usually affects children aged between 6 months and 3 years, most cases happen in 1 year olds, and a child can have it more than once. Croup in adults is rare.

The NHS says it is important to call NHS 111 or see a GP if you think your child has croup, because they may need treatment, and that a doctor may give medicine to shorten the illness. Seek urgent advice if your child is getting worse or not getting better after seeing a GP. Children under 3 months may be referred to hospital.

The NHS says to call 999 or go to A&E if your child is struggling to breathe, with grunting noises or the tummy sucking in under the ribcage, has blue, grey, pale or blotchy skin, lips or tongue, is sleepier than normal or difficult to wake, is unusually quiet and still, is limp or floppy, is very upset or restless and cannot be calmed, or is drooling, finding it hard to swallow or wants to sit rather than lie down. Do not drive your child to A&E yourself.

NHS inform says the virus is passed on by close contact with infected people, as well as through contaminated objects and surfaces, and is often spread by breathing in droplets from infected coughs or sneezes. Other viruses can also cause croup, including influenza A and B, measles in children not immunised, rhinovirus, enteroviruses and RSV.

NHS inform notes croup is more common in late autumn and early winter and tends to affect more boys than girls. Less common causes of croup symptoms include inhaling a small object, inflammation of the epiglottis, severe allergic reaction, irritants and acid reflux. These are the reasons croup should be assessed rather than assumed.

NHS inform says croup can usually be diagnosed by a GP, who checks the symptoms, particularly the sound of the cough. It suggests recording the noise your child makes on your phone, which can help if the child only coughs at night. The GP may check temperature, ask about recent colds, and do a pulse oximetry test to check oxygen levels with a sensor on an earlobe or finger.

The NHS inform page says not to check your child’s throat yourself, as it could trigger a spasm of the airway and make breathing more difficult. NICE CKS grades croup as mild, moderate, severe or impending respiratory failure, and says children with moderate or severe croup, or impending respiratory failure, should be admitted to hospital.

The NHS says most croup is mild and gets better within 48 hours, and that home care means sitting your child upright, comforting them because crying can make symptoms worse, giving plenty of fluids and paracetamol or ibuprofen for fever or discomfort. It advises not to put the child in a steamy room or get them to inhale steam, and NHS inform says steam treatment is not recommended.

NICE CKS says that all children with croup, whether mild, moderate or severe, should receive a single dose of oral dexamethasone, with alternatives available if the child is too unwell for oral treatment. NHS inform says the medicine is a single dose of an oral corticosteroid such as dexamethasone or prednisolone. In severe cases, hospital treatment may include adrenaline or oxygen. NHS inform says cough medicines and decongestants do not help.

Croup is managed in NHS primary care, out-of-hours services, NHS 111 and emergency departments, free at the point of use. Because symptoms are often worse at night, out-of-hours and urgent care routes matter more than planned appointments.

A private paediatrician may be useful for a second opinion. For acute breathing difficulty, the route is always 999 or A&E rather than waiting for a private appointment. Neither route changes the basic approach described by the NHS and NICE CKS.