Mononucleosis In Babies: Symptoms, Complication And Treatment

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Infectious mononucleosis (mono), also known as glandular fever or kissing disease, is a viral illness that causes flu-like symptoms, tiredness, and enlargement of the lymph glands. Mono occurs globally in any season.

Although it is common among adolescents and young adults, infants may contract viruses through the oral secretions of parents, siblings, or anyone who is infected and in close contact with them (1).

Read this MomJunction post to know about the causes, signs, symptoms, diagnosis, treatment, and prevention of mononucleosis in babies.

Causes Of Mononucleosis In Babies

Epstein-Barr virus (EBV) or human gammaherpesvirus is the primary cause of infectious mononucleosis. Other viruses, such as cytomegalovirus, can also cause mononucleosis, but the clinical presentation may vary from EBV infection.

The incubation period of mono can be around six weeks. During this time, the virus replicates in the oral cavity and enters the blood. The exact time of virus transmission is not known (2)

The disease usually spreads from the saliva of infected people. Babies may contract the infection in any of the following ways (1):

Babies may contract mononucleosis if they chew used toothbrushes

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  • Pre-chewing foods (premastication or kiss feeding, which means chewing food in order to feed that to the baby)
  • Straws

It is a contagious disease, and the virus may remain inactive in babies’ throat and blood cells for a long time after the acute illness.

Signs And Symptoms Of Mononucleosis In Babies

Some babies may not develop any symptoms or may have only mild symptoms of mono. The following symptoms are usually seen in a few babies (3) (4):

Skin rash may indicate mononucleosis in babies

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  • Difficulty in swallowing
  • Swollen lymph glands, often in the neck, underarms, and groin
  • Body ache
  • Swollen liver
  • Jaundice (rare)
  • Spleen swelling

Although rare, you may also notice the following signs and symptoms:

The signs and symptoms may disappear in four weeks; however, in some cases, babies may have extreme fatigue for a few more weeks. These symptoms can also be seen in other diseases and, therefore, you may seek medical care for an exact diagnosis.

The virus can remain inactive in the oral cavity and blood cells for a lifetime after the infection. Usually, there is no risk for developing mononucleosis again after the primary infection.

Complications Of Mono In Babies

The course of mononucleosis is comparatively mild in babies. However, there is a risk of developing complications, such as (1) (5):

  • Upper airway obstruction from swollen tonsils
  • Meningitis—inflammation of the membrane covering the brain and spinal cord. Fever, stiff neck, and bulging of the head are often noticed in babies during meningitis.
  • Encephalitis—inflammation of the brain. You may notice sleepiness, skin rash, stiff neck, etc. during encephalitis. Babies may also have seizures during brain inflammation.
  • Guillain-Baree syndrome—a rare complication in which the immune system attacks the nerves. It may occur later in the course of the disease and is often associated with neurological symptoms (6).
  • Myocarditis—an inflammation of the heart muscles often associated with high viral load.
  • Thrombocytopenia a rare form of EBV infection associated with a slight decrease in platelet count.
  • Orchitis—an inflammation of the testes.
  • Rupture of the spleen

Diagnosis Of Mononucleosis In Babies

Your doctor may diagnose mononucleosis from symptoms and examination of the lymph glands. The following tests may be done to confirm the diagnosis (7):

  • Blood tests: White blood cell count and the presence of atypical lymphocytes are crucial to the diagnosis of mono.
A blood test may help diagnose mononucleosis in babies

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  • Monospot test or heterophile antibody test: This test helps identify the antibodies produced as a result of an EBV infection. Antibody analysis helps differentiate the cause of mononucleosis. Viruses other than EBV give negative results during heterophile antibody tests.

Your doctor may also order some additional tests to diagnose mononucleosis. Complications often require ECG or EEG test, or cerebrospinal fluid analysis.

Treatment Of Mononucleosis In Babies

Giving sufficient breastmilk can help babies recover from mononucleosis

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Mononucleosis is a self-limiting disease in healthy babies, and the symptoms are relieved within two to eight weeks. There is no particular therapy or vaccine to treat or prevent mononucleosis. The following ways may help your baby in recovery (8) (9):

  • Giving enough fluids or breastmilk
  • Taking enough rest to recover
  • Administering acetaminophen for fever and pain
  • Administering corticosteroids to reduce throat pain and swelling if the swollen tonsils cause breathing problems

Do not give over-the-counter medications to babies without a doctor’s advice. Your baby may require hospitalization in severe cases. Mono can be critical in babies with low immunity, and they may require supportive treatments and antiviral treatments. Your doctor may prescribe medications based on the severity of symptoms and complications of mono.

Note: Antibiotic treatments are not given since mono is a viral infection. Inappropriate use of antibiotics could lead to resistance.

Prevention Of Mono In Babies

Crushing food before feeding can prevent mono in babies

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There is no approved vaccine or medication to prevent mononucleosis. The following tips may help prevent mono in babies (10):

  • Do not share the baby’s utensils with other family members
  • Grind or crush solid food for babies instead of pre-chewing
  • Keep used toothbrushes or teethers out of babies’ reach

Mononucleosis in babies is not common, but they may develop the disease from an infected adult through kissing, sharing utensils, or exposure to cough. If your baby has mononucleosis, they may show symptoms such as fever, fatigue, swollen liver and spleen, and jaundice. Since mononucleosis is a self-limiting disease, these symptoms may disappear after a few weeks; however, the virus may stay active in the oral cavity for a lifetime. To treat the condition in babies, give them fluids or breast milk and provide rest. Always consult a doctor for the medicines to be administered to the babies. In rare cases, infections with EBV may increase the risk of nasopharyngeal cancer, Hodgkin’s lymphoma, and Burkitt’s lymphoma (11). Therefore, it is best to prevent this disease by not sharing babies’ utensils and keeping used toothbrushes out of their reach.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. Henry H Balfour, Jr, et al.; Infectious mononucleosis; The United States National Library of Medicine
2. Samantha K. Dunmire, et al.; The Incubation Period of Primary Epstein-Barr Virus Infection: Viral Dynamics and Immunologic Events; The United States National Library of Medicine
3. Epstein-Barr Virus and Infectious Mononucleosis; The Centers for Disease Control and Prevention
4. Mononucleosis; The United States National Library of Medicine
5. Infectious Mononucleosis; Johns Hopkins Medicine
6. Guillain-Barré Syndrome; CDC
7. Mononucleosis Tests; Regents of the University of Michigan
8. Epstein-Barr Virus and Infectious Mononucleosis; The Centers for Disease Control and Prevention
9. Mononucleosis Complications; University of Wisconsin Hospitals and Clinics Authority
10. Infectious mononucleosis fact sheet; The Government of New South Wales
11. Henrik Hjalgrim, et al.; Human Herpesviruses: Biology, Therapy, and Immunoprophylaxis.; The United States National Library of Medicine
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Dr Bisny T. Joseph

Dr. Bisny T. Joseph is a Georgian Board-certified physician. She has completed her professional graduate degree as a medical doctor from Tbilisi State Medical University, Georgia. She has 3+ years of experience in various sectors of medical affairs as a physician, medical reviewer, medical writer, health coach, and Q&A expert. Her interest in digital medical education and patient education made...
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Dr. Anjan Bhattacharya

Dr. Anjan Bhattacharya has worked in the field of pediatrics, neonatology and developmental pediatrics both in India and the UK for more than last 30 years, 12 years of that being in the UK.    While working in London, he has developed special interest in developmental pediatrics.  The Child Development Centre of Apollo Gleneagles Hospital has become a reality with...
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