Infectious Mononucleosis (Glandular Fever)
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Infectious Mononucleosis, commonly known as Glandular Fever or "Mono", is a clinical syndrome typically caused by primary infection with the Epstein-Barr Virus (EBV).
It is characterised by the classic triad of:
- Fever
- Pharyngitis (often severe)
- Lymphadenopathy
Key Clinical Pearl: The "Amoxicillin Rash"
If a patient with Mono is mistakenly treated for Strep throat with Amoxicillin or Ampicillin, 80-90% will develop a widespread macular rash. This is not a penicillin allergy but a reaction between the drug and the virus.
Clinical Scenario: The Student's Sore Throat
A 19-year-old university student presents with a 1-week history of severe sore throat, profound fatigue, and night sweats. On exam, she has massive 'kissing tonsils' with white exudate, bilateral posterior cervical lymphadenopathy, and a palpable spleen tip.
Key Teaching Points
- The presence of **Posterior Cervical** nodes is more suggestive of EBV than bacterial tonsillitis.
- Palpable splenomegaly occurs in 50% of cases.
- The fatigue is often the most debilitating symptom and can persist for months.
- Advice regarding contact sports is mandatory to prevent splenic rupture.
- Infectious Agent: Epstein-Barr Virus (Human Herpesvirus 4).
- Transmission: Saliva ("Kissing Disease"), sharing drinks/cutlery.
- Age:
- Children: Infection is often asymptomatic or mild.
- Adolescents/Young Adults (15-25y): Peak incidence of symptomatic Glandular Fever.
- Seroprevalence: >90% of adults worldwide are EBV seropositive (have been infected).
- Entry: Virus enters via oropharyngeal epithelium.
- Infection: Infects B-lymphocytes.
- Latency: EBV becomes latent in memory B cells (lifelong infection).
- Immune Response:
- The "Atypical Lymphocytes" seen on blood film are actually CD8+ Cytotoxic T-cells reacting against the infected B cells.
- This massive T-cell expansion causes the lymphadenopathy and splenomegaly.
Incubation Period: 4–6 weeks.
Symptoms
Signs
- Throat: Check airway patency. Look for exudate and petechiae.
- Neck: Palpate anterior and posterior chains.
- Abdomen: Gentle palpation for spleen. (Do not prod vigorously due to rupture risk).
- Skin: Check for rash.
Bedside
- Monospot Test: Detects Heterophile Antibodies.
- Sensitivity: 85%.
- False Negatives: Common in first week of illness or in young children (<10y). Repeat if suspicion remains high.
Laboratory
- FBC:
- Leukocytosis (10-20,000).
- Lymphocytosis (>50% of white cells).
- Blood Film: Atypical Lymphocytes (>10%).
- LFTs: Elevated transaminases (ALT/AST) in 90% of cases (EBV Hepatitis). Usually self-limiting.
- EBV Serology (if Monospot negative):
- IgM VCA (Viral Capsid Antigen): Acute infection.
- IgG VCA / EBNA: Past infection (Immunity).
There is no specific antiviral treatment. Management is supportive.
1. Symptom Control
- Analgesia: Paracetamol/NSAIDs for fever and throat pain.
- Fluids: Maintain hydration.
- Rest: As needed, but prolonged bed rest not mandated. Mobilise as tolerated.
2. Corticosteroids
- Routine use is NOT recommended.
- Indications:
- Airway obstruction (stridor, kissing tonsils).
- Severe thrombocytopenia.
- Haemolytic anaemia.
- Dose: Dexamethasone or Prednisolone (short course).
3. Antibiotics
- Avoid Amoxicillin.
- If concurrent Strep throat is suspected (throat swab positive), use Penicillin V or Erythromycin.
4. Lifestyle Advice (Crucial)
- Contact Sports: Avoid for 8 weeks (risk of splenic rupture is highest in first 3 weeks, but can persist). Includes rugby, football, judo, etc.
- Alcohol: Avoid if LFTs deranged.
- Fatigue: "Post-viral fatigue" can last months. Gradual return to school/work.
- Splenic Rupture: Rare (0.1-0.5%) but potentially fatal. Spontaneous or traumatic. Presents with L shoulder tip pain (Kehr's sign) and shock.
- Airway Obstruction.
- Hematological: Autoimmune Haemolytic Anaemia (Coombs positive), Thrombocytopenia.
- Neurological: Guillain-Barre Syndrome, Meningoencephalitis, Bell's Palsy.
- Chronic Active EBV: Very rare.
- Malignancy: EBV is associated with Burkitt's Lymphoma, Hodgkin's Lymphoma, and Nasopharyngeal Carcinoma (rare long-term associations).
- Acute symptoms resolve in 2-4 weeks.
- Fatigue usually resolves by 3 months.
- Immunity is usually lifelong.
- NICE CKS: Glandular Fever (Infectious Mononucleosis).
- CDC: EBV Guidelines.
What is Glandular Fever? It is a viral infection (EBV) that affects your glands (lymph nodes). It is often called the "Kissing Disease" because it spreads through saliva.
What are the symptoms? You feel like you have severe flu. A very sore throat, high fever, swollen glands in the neck, and extreme tiredness are typical.
How long does it last? The worst symptoms last 2-3 weeks, but the tiredness can drag on for months. You might feel "washed out" for a long time.
Is there a cure? No medicine kills the virus. Antibiotics do not work (and can cause a rash). Your body's immune system has to fight it off. You need rest, plenty of fluids, and painkillers.
Why can't I play sports? The virus causes your spleen (an organ under your ribs on the left) to swell up. If you get hit in the tummy during sport, the spleen can burst, which causes dangerous internal bleeding. You must avoid contact sports for at least 8 weeks.
- NICE CKS. Glandular fever (infectious mononucleosis). 2021.
- Lennon P, et al. Management of the airway in infectious mononucleosis. Auris Nasus Larynx. 2020.
- Vnea P. Splenic rupture in infectious mononucleosis: a systematic review. Mil Med. 2018.