Viral exanthemas are widespread rashes caused by systemic viral infections. They often occur in children but can affect adults. Recognising the pattern of rash, associated systemic features, and risk groups (especially pregnancy) is crucial for diagnosis and management.

📊 Viral Exanthems – Key Features & Management

Organism / Disease	Key Clinical Features	Management / Public Health / Notes
🟠 Measles (Rubeola)	👶 High fever, 🤧 cough, 🤒 coryza, 👁 conjunctivitis (“3 C’s”), 🟡 Koplik spots. Rash starts on face → spreads downward 💧.	💊 Supportive care (fluids, antipyretics), ⚠️ isolate, 📢 notify public health. Vitamin A only in severe/hospitalised cases. Extremely contagious 🦠.
🟢 Rubella (German Measles)	👶 Mild fever 🌡️, lymphadenopathy 👂 (posterior auricular / suboccipital). Pink maculopapular rash 🌸 starting on face.	💊 Supportive care. ⚠️ Avoid exposure of pregnant women 🤰 (risk of congenital rubella syndrome). 📢 Notifiable disease.
🔵 Varicella (Chickenpox)	🤒 Fever + malaise, 🩵 pruritic vesicles “dew drop on a rose petal” 💧 in crops, lesions at different stages 🌈, starts on trunk.	💊 Supportive care. ⚡ Aciclovir for adults, pregnant 🤰, or immunocompromised 🧬. ❌ Exclude from school/work until vesicles crusted.
🌷 Roseola (HHV-6, Exanthem Subitum)	👶 High fever 🌡️ 3–5 days, then sudden pink maculopapular rash 🌸 after fever resolves. Usually infants/toddlers 👶.	💊 Supportive care, antipyretics for fever. ✅ Reassure parents. Self-limiting.
🟥 Erythema Infectiosum (Fifth Disease, Parvovirus B19)	👧 “Slapped cheek” facial rash 🖐️ → lacy rash on limbs 🌈. Mild systemic features 🌡️.	💊 Supportive care. ⚠️ Avoid contact with pregnant women 🤰 (risk of fetal hydrops). Usually self-limiting in healthy children 👶.
🖐️ Hand, Foot, and Mouth Disease (HFMD)	👶 Fever 🌡️, sore throat 😷, oral ulcers 👄, vesicles on hands 🖐️ and feet 🦶. Mostly young children 👶.	💊 Supportive care, maintain hydration 💧. Usually mild; ❌ exclude from nursery/school while symptomatic.

📌 Viral Exanthems – Exam & OSCE Tips

High-yield points for UK medical exams: pattern recognition, red flags, risk groups, and NICE-aligned management.

1️⃣ Pattern Recognition

🟠 Measles (Rubeola) - Rash: face → trunk → limbs 💧 - Prodrome: 🤧 cough, 🤒 coryza, 👁 conjunctivitis (“3 C’s”) - Koplik spots 🟡 = pathognomonic - OSCE tip: ask about vaccination history 💉 and exposure 🌍
🟢 Rubella (German Measles) - Rash: face, milder than measles 🌸 - Posterior auricular / suboccipital lymphadenopathy 👂 - Key risk: pregnancy exposure 🤰 → congenital rubella - OSCE tip: ask last MMR vaccination 💉 and pregnancy risk
🔵 Varicella (Chickenpox) - Lesions in crops at different stages 🌈 - Rash: trunk → face/limbs 💧 - Pruritic vesicles: “dew drop on rose petal” 🌹 - Risk groups: adult, pregnant 🤰, immunocompromised 🧬 - OSCE tip: check fever onset relative to rash 🌡️
🌷 Roseola (HHV-6, Exanthem Subitum) - High fever 🌡️ 3–5 days → rash appears after fever - Usually infants/toddlers 👶 - OSCE tip: reassure parents ✅
🟥 Erythema Infectiosum (Fifth Disease, Parvovirus B19) - “Slapped cheek” 🖐️ → lacy rash on limbs 🌈 - Mild fever 🌡️ - Important in pregnancy 🤰 (fetal hydrops) - OSCE tip: ask about school/nursery exposure
🖐️ Hand, Foot, and Mouth Disease (HFMD) - Fever 🌡️ + oral ulcers 👄 + vesicles on hands 🖐️ and feet 🦶 - Mostly children <5 👶 - OSCE tip: ask about contact with other children 👦👧, hydration 💧

2️⃣ Red Flags for Exams / Clinical Safety

⚠️ Pregnancy exposure: Rubella, Parvovirus B19, Varicella 🤰
⚠️ Immunocompromised or unvaccinated adults: Measles, Varicella 🧬
⚠️ Severe dehydration in children: vomiting, poor oral intake 💧
⚠️ Secondary complications: Pneumonia (Measles, Varicella), Aplastic crisis (Parvovirus B19) 🫁🩸

3️⃣ Key Clinical Exam / History Points

✅ Vaccination history 💉 (MMR, Varicella)
✅ Prodromal symptoms: fever 🌡️, malaise, cough 🤧, coryza, conjunctivitis 👁
✅ Rash timing & distribution: face → trunk → limbs 💧
✅ Associated lymphadenopathy: posterior auricular/suboccipital 👂
✅ Exclusion & isolation advice: school/nursery/hospital ❌

4️⃣ OSCE / Short-Answer Tips

👀 Visual cue: always describe rash pattern & evolution 🌸💧
⚠️ Risk assessment: consider pregnancy 🤰 & immunocompromised 🧬
📢 Public health: mention notification if notifiable disease (Measles, Rubella, Varicella)
💊 Management: supportive care (fluids, antipyretics); antivirals only for high-risk groups ⚡

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Viral exanthema ✅