Influenza (“the flu”) is a viral illness caused by influenza strains A, B, and C. Influenza is an infection that affects the respiratory system including the nose, throat, and lungs. The flu is extremely contagious and is normally spread during the colder months. Also, because children were mostly at home during COVID, it seems that they are more susceptible to catching whatever illness is going around so we have seen a lot of children with the flu this year.

The flu, Influenza, Child with the flu - sneezing

SYMPTOMS:

  • Fever
  • Cough
  • Sore throat
  • Muscle aches
  • Body aches
  • Congestion
  • Nausea
  • Vomiting
  • Diarrhea
  • Headache
  • Lethargy
  • General malaise

 

CAUSES:

Influenza is caused by specific influenza strains A, B, and C. Although many other viral illnesses have similar symptoms, they should not be confused with the actual influenza virus.

DIAGNOSIS:

Observance of symptoms of the flu at a certain time of year. If it is influenza season, the symptoms are consistent with the flu, and there is flu in the community, then one would suspect influenza. A lab test can confirm influenza. There are rapid tests that can give results in 10-30 minutes.  The test sample is obtained by taking a nose or throat swab. A viral culture, serology, polymerase chain reaction, or immunofluorescence can also confirm the flu, however, these tests can take hours to days depending on the lab.

CONTAGION:

The flu is a respiratory illness and is contagious by the respiratory route. The virus can be spread by coughing or sneezing. Also, the flu can be spread by what is referred to as droplet infection. For example, a person may cough on an object. Another person may then touch the object, pick up the virus, and then touch their nose, mouth, or eyes. This is contagious from 1 day before the development of symptoms to 7 days after the development of symptoms.

TREATMENT:

There are 4 medications approved for the treatment of influenza. These are amantadine, rimantadine, Zanamivir  (Relenza), and osteltamivir (Tamiflu). Amantadine and rimantadine will treat influenza A only. Oseltamivir and Zanamivir will treat influenza A and B. The table below shows doses by age and weight.

OUTCOME:

The outcome of influenza can vary. For a generally healthy individual, typically there will be symptoms for a few days with complete recovery. However, in immunosuppressed people, the elderly, and children under 2 years of age, this can be a more serious illness.

Complications include:

  • Pneumonia
  • Dehydration
  • Ear and sinus infections
  • Croup
  • Encephalitis
  • Reyes syndrome (liver failure when aspirin is given with influenza)
  • Exacerbations of any chronic illness such as asthma, cystic fibrosis, heart or lung disease, or diabetes

 

DISCUSSION:

The most confusing thing about influenza is that the term “the flu” has become a generic term meaning “I feel sick”. In the days before influenza medications, this was no problem. Since “the flu” was viral anyway, there was nothing you could do except rest, take fluids, cold medicines, acetaminophen, or ibuprofen, wait it out, and treat complications if they arose. Now that we have medicines that are specific for the actual influenza virus, it is important to distinguish between the influenza virus and other viruses that cause similar symptoms. Since we can test for influenza and either treat it or prophylax close contacts, we should now be more cautious about the term “the flu”. We should only use it to mean the influenza virus, which can only be properly diagnosed through lab testing.

The influenza virus is seasonal. It happens in cooler weather, typically from September to March. The best way to prevent this illness is by vaccination. There are currently two types of vaccines, injected and nasal. Influenza is a strange virus in that each year it changes a little in terms of which strains will be most prevalent. The vaccine produced each year is based on which strains will most likely be prevalent that year. Typically the vaccine contains two type A and one type B strain.

For example, for the 2003/2004 season, the trivalent inactivated influenza vaccine prepared included A/Moscow/10/99 (H3N2)-like, A/New Caledonia/20/99 (H1N1)-like, and B/Hong Kong/330/2001-like antigens. The predictions are not always perfect and sometimes a strain that was not expected becomes prevalent. The vaccine will last 9-12 months once given. The current vaccine recommendations are to vaccinate all children between the ages of 6 months to 2 years with the injectable vaccine, which is an inactivated vaccine. Also, any child over 6 months old who is considered “at risk” should receive the injection. At-risk children would include those with heart or lung disease, asthma, immunosuppressive diseases, those on aspirin therapy for any reason, or those with any chronic illness. Children under 9 years of age get 2 doses one month apart from the first season they receive this vaccine. Subsequently, the dose would be one injection per season. The nasal flu vaccine (Flumist) offers a new option. This vaccine is a live virus vaccine that can be given to people from 5-49 years of age. Again, if a child is under 9 years of age they would need two doses the first time this is given. For the nasal flu vaccine, the doses need to be 2 months apart.

Early diagnosis can be very helpful. The influenza medications work best if given within 48 hours of the start of symptoms. The medicines can lessen the course of the flu and prevent complications. Also, some of these medications can be used for prevention. If a close contact has the flu it may be a good idea to prophylax the people around the close contact.

ONE DOCTOR’S OPINION:

I always say that you only get the flu once; after that, you’ll choose to get the vaccine. This is a miserable illness. Minimally, you feel terrible for a few days. Also, it can cause death. I know what the current recommendations are, but I don’t understand why we don’t vaccinate everyone. What would be the harm? Sure, you can’t give the vaccine to children under 6 months of age or anyone allergic to its components but what about everyone else? Why take the chance? The introduction of the Flumist vaccine is great because it eliminates having to get a shot. Also, it seems to work a little better than the injection. The package insert says to not give it to children under 5 years of age or asthmatics, but I feel comfortable giving it at younger ages and to asthmatics who are not in the middle of an asthma exacerbation.

My way of handling the flu would be to vaccinate everyone as soon as the vaccine arrives. Then, if someone has the symptoms anyway, I would do a rapid flu test in my office. If they have influenza then I would use Tamiflu. I would also prophylax close contacts. This may not be the most cost-effective way of handling the flu but it would be the healthiest. I have seen too many complications and too many very miserable individuals to take this virus lightly.  Only call it “the flu” if it is indeed the influenza virus. Calling a flu-like illness the flu can cause a lot of confusion for the doctor. We don’t know if someone was exposed to the influenza virus and needs prophylaxis or if they were exposed to someone with a bad cold and need rest and fluids.

 

Written by Dr. Michael Bornstein, who has 30 years of experience as a pediatrician. 

Disclaimer: The contents of this article, including text and images, are for informational purposes only and do not constitute a medical service. Always seek the advice of a physician or other qualified health professional for medical advice, diagnosis, and treatment.