What is it, and what are the symptoms

RSV is a virus that causes bronchiolitis. Bronchiolitis differs from bronchitis, which more commonly affects adults and is an upper airway infection (see figure 1). Other viruses that cause bronchiolitis are influenza, rhinovirus, and human metapneumovirus, to name a few. Because many different viruses can cause it, children often get bronchiolitis more than once and often more than once in the same year. Bacteria rarely cause it.

Bronchiolitis is an infection of the smallest airways, called the bronchioles. If the lungs were a tree, the bronchioles would be the smallest roots at the bottom of the tree system (See Figure 1). They are part of the lower airways. However, the infection usually begins in the upper airways spreading down into the lower. Symptoms of upper airway infection include runny nose and cough. Like many infections, there also may be fever, an associated symptom. As the infection spreads down the airways into the lower tracts, signs of respiratory distress and difficulty breathing may appear; typically, this occurs on days 3 to 5 of the illness.

from: https://www.healthline.com/health/bronchiolitis-vs-bronchitis#symptoms

The smaller the child, the more likely an infection of the lower airways is to cause difficulty breathing. As children grow, so do their lungs. Lungs do not reach their full maturity until 20-25 years! So small children, small airways. If you think of bronchioles like straws, an adult would be like an ordinary straw and a small child like a stirring straw. If they are straw wall swells, as the bronchiole walls swell during an infection, it gets harder to suck air through. The narrowing can also lead to a whistling sound, like a wheeze. The wheezing sound may be confused for asthma. In addition to the swelling, mucous production blocks the upper and lower airways and, when dried up, becomes like cement, which is difficult for small children to clear. The airway plugging and swelling are at the heart of the problem for little airways and is precisely why small children are affected much more by bronchiolitis. Typically, children under 6 months are most at risk for respiratory distress from bronchiolitis, but it can occur in children up to 2 years old.

from: KidsHealth. https://kidshealth.org/en/parents/bronchiolitis.html

What is going on in the news?

Almost every year, the viruses that cause bronchiolitis come out of their “envelopes” because they are sensitive to temperature. That time of year is usually winter and early spring, with a peak in February. The temperature sensitivity is why less bronchiolitis is seen in more southern parts of the country and is seen earlier in the year.

The graph below shows previous years’ cases, and you can see the peaks usually during the late winter months. Currently, the number of RSV infections is more similar to the peak we typically see in February. What has yet to be discovered is if the numbers will continue to rise or start to fall, i.e., is this just an unusually early peak? There are many theories about why there are so many cases early this year. One is that children usually would be exposed to RSV annually but were not during the pandemic. Those children, therefore, do not have immunity and are now contracting RSV, leading to increased cases compared to pre-pandemic years. There is no way to know the answer to that question, but we all certainly hope this is the peak. 

 

Bermúdez Barrezueta, L., Matías Del Pozo, V., López-Casillas, P. et al. Variation in the seasonality of the respiratory syncytial virus during the COVID-19 pandemic. Infection 50, 1001–1005 (2022). https://doi.org/10.1007/s15010-022-01794-y.

Bronchiolitis, and RSV, are not new to the pediatric world. Every “RSV season,” pediatric care providers prepare to have increased ER, hospital, and critical care unit admissions due to bronchiolitis. In some cases, staffing models are built around this. An unseasonal peak can catch pediatric care providers off guard. This, combined with the reduced pediatric units being seen around the country, leaves children without treatment beds. Why are pediatric services being cut? Pediatric services provide less income than adults. More on the topic here: https://www.nytimes.com/2022/10/11/health/pediatric-closures-hospitals.html.

Spread 

Droplets spread RSV from coughing or sneezing. It can also be transmitted y direct contact like kissing or touching an infected surface. Those with RSV can be contagious for 3 to 8 days and may be contagious a day or two before they develop symptoms.

Diagnosis 

The diagnosis can be made just by the symptoms. There are always nasal swabs, specifically RSV. However, other viruses cause bronchiolitis. Therefore, a negative RSV test does not mean a patient does not have bronchiolitis. The treatment, no matter the virus causing it, remains the same.

Treatment at home 

The key to treating bronchiolitis is to try to undo the two airway problems caused by (1) swelling of the airway tubes and (2) plugging those tubes by mucous. Remember that dry mucous is more like cement and harder for small children to clear. So therapy is aimed at keeping the mucous hydrated and thin as well as clearing those airways of mucous.

The mainstay of outpatient treatment is nasal saline, suctioning, and hydration. The function of the upper airway is to act as a filter and humidify the lower airways; if they are blocked or infected, the infection spreads. To keep them open and clear:

1. Instill a few drops of saline into each nare; this loosens the mucous and reduces swelling of the airway wall. The nasal saline should be sterile, so bacteria, mold, and fungus are not introduced into the airway.
2. Follow nasal saline with suction.

I prefer a hospital-grade suction, like the nozebot, but any suction device may be used. You may need to repeat this process several times to get the mucous out.

Babies are obligate nose breathers, so they can breathe through their nose and eat with the mouth by bottle or breast. If a child’s nose is swollen and blocked, they will eat less. Why? The baby will choose to breathe over to eat. Breathing through the mouth is much less efficient for a child, so I recommend saline and suction, especially before each feed.

Humidifiers and steam showers are also helpful in keeping mucous moisturized, thinner, and easier to clear from the airways. It is best in the morning and night for steam showers. Humidifiers should be cool mist. Please pay close attention and regularly clean the machine to avoid mold and fungus. The ideal humidity for your child’s room is 30-50%. Too much moisture can allow other organisms, like mold, to grow.

When to see a doctor 

You want to consult a doctor immediately if your child has respiratory distress. Signs of distress include breathing fast. Your child may start using extra muscle to help them breathe. For example, the muscles between the rib may be moving in and out. Additionally, the child’s nose may flare in and out, and they may grunt as they attempt to “open” their airways. Find examples of what respiratory distress looks like in children with videos here: https://www.kidshealth.org.nz/signs-children-are-struggling-breathe.

All this extra breathing is exercise; eventually, the child will tire. Call your child’s doctor immediately if you see any of these signs.

In addition to signs of distress, there are some patients I like parents to call me at the first signs of a respiratory infection because they are at higher risk for complications. I ask caretakers to contact me if they have any symptoms of a respiratory infection if their child is:

1. Premature
2. Less than 12 weeks old
3. Has a cardiopulmonary disease
4. Is immunocompromised

Another reason to call your child’s doctor is if they have persistent fever (more than 48hr or greater than 100.4F) or are irritable even after treating the fever. RSV is associated with an increased risk of urinary tract infections but more commonly causes ear infections. Any viral infection of the upper respiratory tract can cause excess fluid behind the middle ear, which then becomes infected by bacteria, causing an ear infection.

Dehydration may be another side effect of a URI/LRI. Children who cannot breathe their nose may not be able to drink, or breast/bottle feed well. Signs of dehydration include not making tears when they cry or decreased volume or amount of wet diapers. Call your doctor for advice if your child is not drinking as they usually do or shows the above signs of dehydration.

Return to school 

A child may return to school when they are fever-free without medicine for at least 24 hours. You will also want to ensure your child is eating and drinking as usual.

References: 

1. Bermúdez Barrezueta, L., Matías Del Pozo, V., López-Casillas, P. et al. Variation in the seasonality of the respiratory syncytial virus during the COVID-19 pandemic. Infection 50, 1001–1005 (2022). https://doi.org/10.1007/s15010-022-01794-y.
2. Gotter, Ana. “Bronchiolitis vs. Bronchitis: Symptoms, Causes, and Treatments.” Healthline, Healthline Media, 26 Apr. 2017, https://www.healthline.com/health/bronchiolitis-vs-bronchitis#symptoms. 
3. Lissienko, Katherine. “Signs That Children Are Struggling to Breathe.” KidsHealth NZ, KidsHealth NZ, 22 Aug. 2019, https://www.kidshealth.org.nz/signs-children-are-struggling-breathe. 
4. “Bronchiolitis (for Parents) – Nemours Kidshealth.” Edited by Larissa Hirsch, KidsHealth, The Nemours Foundation, Oct. 2022, https://kidshealth.org/en/parents/bronchiolitis.html. 
5. Baumgaertner, Emily. “As Hospitals Close Children’s Units, Where Does That Leave Lachlan?” The New York times, 11 Oct. 2022, www.nytimes.com/2022/10/11/health/pediatric-closures-hospitals.html.