Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Measles, mumps, rubella and varicella
Paediatrics and child health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Respiratory, neurological or high-risk-host disease
Breathing difficulty, hypoxaemia, encephalopathy, seizure, severe dehydration, haemorrhagic lesions or rapidly painful inflamed chickenpox skin suggests a serious complication. Varicella or measles can be life threatening in neonates or immunocompromised children.
Action: Arrange emergency paediatric assessment and warn the receiving service before arrival so airborne or respiratory isolation is ready. Stabilise airway, breathing, circulation and glucose, investigate bacterial and neurological complications, and obtain infection-specialist advice on intravenous antiviral, antimicrobial, immunoglobulin and critical-care treatment.
Overview
Differentiate four vaccine-preventable viral infections, recognise severe and pregnancy-related risks, arrange testing and notification without exposing others, and use current MMRV and post-exposure pathways safely.
These four infections overlap through fever, rash and respiratory transmission, but the timing and morphology separate them. Measles has a severe catarrhal prodrome; rubella is milder with posterior nodes; varicella has lesions at mixed stages; mumps centres on salivary-gland swelling.
Vaccination changes probability but does not make infection impossible. Record exact products and dates rather than writing 'fully immunised', because current cohorts may have received MMR, MMRV, single-antigen vaccine abroad or incomplete doses.
Measles is exceptionally contagious and spreads through airborne and respiratory particles. A child can infect others from about 4 days before through 4 days after rash onset, so waiting-room exposure can occur before diagnosis.
Mumps spreads by droplets and close contact. Parotitis may be absent, unilateral or bilateral, and neurological disease can precede, follow or occur without gland swelling.
Practice
Two practice questions
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Question 1 of 2
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Paediatrics and child healthOriginal SBA
Varicella exposure prophylaxis
A susceptible immunosuppressed 8-year-old has a significant household chickenpox exposure but remains well. Which current UKHSA approach is preferred after specialist risk assessment?
Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem ·
Rubella often causes little illness in children, yet infection during early pregnancy can damage fetal hearing, eyes, heart and neurodevelopment. The important history therefore extends beyond the child to pregnant household and healthcare contacts.
Varicella spreads by airborne droplets and direct contact with vesicular fluid. It is infectious before rash and until lesions have crusted; new crops create the diagnostic mixture of papules, clear vesicles and scabs.
Ask about rash sequence, fever relative to rash, cough, coryza, conjunctivitis, gland pain, pruritus, vaccination, known exposure, travel, pregnancy contacts and immune compromise. Photograph evolution only with consent and appropriate governance.
Examine hydration, breathing and mental state before describing lesions. Inspect oral mucosa for Koplik or vesicular lesions, palpate posterior nodes and parotids, and assess testes, abdomen, gait and neurology when symptoms indicate.
Testing should not create transmission. Telephone the health protection or virology service, use designated isolation and collect the advised specimen with correct personal protective equipment rather than sending an infectious child through routine phlebotomy.
Routine uncomplicated disease receives supportive care. Antibiotics do not treat these viruses; use them only for a separate bacterial complication such as varicella-associated cellulitis or pneumonia.
Antiviral treatment and post-exposure prophylaxis are risk-dependent. Immunocompromised children, neonates and severe varicella require specialist plans; live vaccines are generally unsuitable during severe immunosuppression.
Prevention uses the current national cohort schedule and exposure-specific public-health advice. A disease episode does not automatically prove immunity to the other three MMRV components, so complete outstanding eligible doses after recovery.
Key points
Measles classically causes high fever, cough, coryza and conjunctivitis followed by Koplik spots and a maculopapular rash spreading from face and hairline downwards.
Mumps usually causes painful unilateral or bilateral parotid swelling after fever, malaise and headache; orchitis, meningitis, pancreatitis and hearing loss are important complications.
Rubella is often mild or asymptomatic, with low-grade fever, post-auricular or suboccipital lymphadenopathy and a fine rash spreading from face to trunk; pregnancy exposure is the critical emergency.
Varicella produces intensely itchy crops of macules, papules, vesicles and crusts at different stages, usually concentrated on scalp and trunk, with possible mucosal lesions.
Call ahead before face-to-face assessment of suspected measles, rubella, mumps or varicella. Separate the child from vulnerable patients and apply the organism-specific respiratory or airborne precautions.
Measles, mumps and rubella are notifiable on clinical suspicion. Contact the health protection team promptly; do not wait for laboratory confirmation.
First-line diagnosis is clinical plus public-health-directed virology. Measles and rubella testing is coordinated with UKHSA; mumps commonly uses an oral-fluid sample; uncertain varicella can be tested by lesion PCR.
Aetiology
01
Measles virus
A morbillivirus spreads efficiently through airborne respiratory particles and causes systemic infection after replication in the respiratory tract.
02
Mumps virus
A paramyxovirus spreads through droplets and saliva, with tropism for salivary glands, nervous tissue, gonads and pancreas.
03
Rubella virus
Rubella spreads by respiratory contact and is usually mild after birth, but transplacental infection can disrupt fetal organ development.
04
Varicella-zoster virus
Primary airborne or contact infection causes chickenpox, after which latent sensory-ganglion virus can later reactivate as shingles.
Pathophysiology
1
Measles systemic dissemination
Respiratory replication leads to viraemia, immune-cell infection and a cell-mediated rash, with transient immune suppression increasing secondary infection risk.
2
Mumps glandular spread
Viraemia carries virus to parotid and other glandular tissues, meninges, testes or ovaries, causing oedema and inflammatory pain.
3
Rubella fetal injury
Maternal viraemia can cross the placenta and impair cellular growth and organogenesis, especially when infection occurs early in pregnancy.
4
Varicella crops and latency
Successive viraemic seeding creates lesions at different stages, while surviving virus establishes latency in sensory nerve ganglia.
Clinical features and red flags
Measles sequence
Identify high fever with cough, coryza and conjunctivitis, possible Koplik spots, then a confluent face-to-body maculopapular rash.
Mumps parotitis
Look for painful swelling that lifts the ear lobe and obscures the mandibular angle, with unilateral or bilateral involvement.
Rubella pattern
Seek posterior auricular or suboccipital nodes, mild prodrome and a fine facial rash spreading rapidly to trunk and limbs.
Varicella morphology
Find pruritic lesions in successive crops at mixed macular, papular, vesicular and crusted stages, often concentrated centrally.
Severe complication screen
Assess breathing, hydration, consciousness, gait, focal neurology, secondary skin pain, persistent fever and bleeding in every rash illness.
Vulnerable-contact screen
Ask immediately about newborn, pregnant and immunocompromised contacts because prophylaxis windows begin from the exposure, not the test result.
Red flags requiring action
Suspected measles with respiratory distress, hypoxaemia, dehydration, altered consciousness or seizure requires urgent hospital assessment with advance infection-control warning.
Chickenpox with recurrent fever, fever beyond day 3 of rash, respiratory symptoms, neurological change, bleeding, petechiae, haemorrhagic rash or new lesions after day 5 needs urgent paediatric review.
Investigations
01First-line: clinical pattern and exposure historyFirst stepFirst line
Why
Form a working diagnosis while arranging safe infection-control and notification.
Interpretation and limitations
Sequence and morphology are more discriminating than rash colour alone; vaccination lowers but does not eliminate probability.
02Public-health-directed measles or rubella testing
Why
Confirm a notifiable infection and guide contact protection and surveillance.
Interpretation and limitations
Contact the health protection team first and collect the specified oral-fluid, throat, urine or blood specimens using the current pathway.
03Mumps oral-fluid testing
Why
Detect virus or antibody in a compatible parotitis or outbreak presentation.
Interpretation and limitations
Coordinate through public health; timing, vaccination and previous infection affect results, so a negative test needs clinical and epidemiological interpretation.
04Confirmatory varicella lesion PCRConfirmatory
Why
Resolve atypical rash or establish infection in a high-risk child when the result changes management.
Interpretation and limitations
Swab vesicle fluid or the base of a fresh lesion using virology instructions; uncomplicated classic chickenpox usually needs no test.
Differential diagnosis
01
Other viral exanthem
Roseola, parvovirus, enterovirus and adenovirus differ in their fever-rash sequence, distribution, mucosal findings and exposure history.
Neck stiffness, altered consciousness, seizure or non-blanching rash requires immediate bacterial treatment even when a viral illness is possible.
04
Drug eruption
Medication timing, symmetrical morbilliform rash and absence of the characteristic infective prodrome may support a drug reaction, including severe mucosal variants.
05
Other parotid disease
Bacterial parotitis, salivary obstruction, dental infection and cervical lymphadenitis can cause unilateral facial swelling without mumps viraemia.
Management
01Suspected caseIsolate, assess and notifyFirst stepMeasles, mumps, rubella or varicella is clinically possible.+
1Keep the child away from shared clinical areas and tell the receiving service before any face-to-face attendance.
2Assess physiological severity and high-risk host status, then apply respiratory or airborne isolation appropriate to the virus.
3Notify measles, mumps or rubella on suspicion and arrange UKHSA-directed testing; seek public-health advice for significant varicella exposures or clusters.
02Uncomplicated illnessProvide supportive treatmentThe child is stable, drinking and has no serious complication or vulnerable-host indication.+
1Give fluids, rest, skin care and paracetamol for distress using the current age-and-weight dose.
2Avoid aspirin in every child and avoid ibuprofen or other NSAIDs during chickenpox.
Complications
01
Measles pneumonia or encephalitis
Lower-respiratory disease, acute encephalitis and rare delayed subacute sclerosing panencephalitis account for substantial measles morbidity and mortality.
02
Mumps neurological or gonadal disease
Aseptic meningitis, encephalitis, orchitis, oophoritis, pancreatitis and hearing loss occur more often after puberty but can affect children.
03
Congenital rubella syndrome
Fetal infection may cause sensorineural deafness, cataracts, cardiac lesions, growth restriction and significant long-term neurodevelopmental impairment.
04
Varicella bacterial superinfection
Disrupted skin permits invasive group-A streptococcal or staphylococcal cellulitis, severe necrotising infection, bacteraemia and toxic shock.
05
Varicella visceral or neurological disease
Pneumonitis, hepatitis, encephalitis, cerebellar ataxia and disseminated infection are disproportionately concentrated in neonates and immunocompromised hosts.
Monitoring and follow-up
Review breathing, hydration, consciousness and rash evolution; urgent deterioration may occur after an apparently typical prodrome.
For chickenpox, track fever relative to rash day, new-lesion formation, focal skin pain, respiratory symptoms, gait and neurological behaviour.
Monitor renal function and fluid balance during intravenous aciclovir or when dehydration raises the risk of drug crystalluria.
Confirm notifiable-disease testing and health-protection actions, including identification of pregnant, neonatal and immunocompromised contacts.
Arrange disease-specific follow-up for encephalitis, ataxia, hearing change, orchitis, pneumonia or severe skin and soft-tissue injury.
After recovery or prophylaxis, reconcile the immunisation record and schedule remaining MMRV or MMR doses using current cohort rules and blood-product intervals.
Special situations
Fever-rash order discriminates
Measles has prominent catarrh before rash, while roseola often defervesces as rash appears and varicella lesions arrive in crops.
Mild rubella carries external risk
A comfortable child may still represent an urgent fetal-exposure problem for a susceptible pregnant contact.
Varicella pain can precede necrosis
Disproportionate focal pain or recurrent fever may reveal invasive bacterial infection before dramatic erythema becomes visible.
Prophylaxis has a clock
Measles vaccine or immunoglobulin and varicella antivirals use different windows, so the first exposure date must be established promptly.
Cohort determines second dose timing
The 2026 MMRV transition gives some children an 18-month second dose while older cohorts retain a preschool offer.
Common pitfalls
01
Do not bring suspected measles through an unprepared waiting room; call ahead and isolate on arrival.
02
Do not exclude measles solely because one or two vaccine doses are recorded when the clinical and exposure history is compelling.
03
Do not confuse a negative tumbler test early in illness with exclusion of a serious infection.
04
Do not give aspirin to a child or ibuprofen during chickenpox.
05
Do not use prophylactic aciclovir timing or dose to treat established varicella rash.
06
Do not overlook pregnant, newborn or immunocompromised contacts while focusing on the mildly affected child.
07
Do not wait for laboratory confirmation before notifying suspected measles, mumps or rubella.
08
Do not assume natural infection with one virus completes protection against the other MMRV components.
Management is usually supportive: fluids, rest and suitable paracetamol for discomfort. Never give aspirin under 16, and avoid ibuprofen or other NSAIDs in chickenpox.
Admit varicella in babies under 7 days, immunocompromised children, serious complications or continuing new lesions beyond day 5; babies aged 7 to 28 days need low-threshold review.
After significant varicella exposure, current UKHSA first-choice prophylaxis for susceptible immunosuppressed people is oral aciclovir or valaciclovir on days 7 to 14; neonatal exceptions may need immunoglobulin.
After measles exposure, health protection selects MMRV or MMR ideally within 72 hours for eligible susceptible contacts, or immunoglobulin within 6 days for defined vulnerable contacts.
From January 2026 the routine offer uses MMRV. The July 2026 schedule gives a dose at 1 year and an 18-month dose for children born on or after 1 July 2024, with cohort-specific preschool arrangements.
Red, hot, exquisitely painful or rapidly spreading skin around varicella lesions may indicate invasive group-A streptococcal or staphylococcal infection, even when colour change is subtle.
A newborn with possible varicella, or any immunocompromised child exposed to or developing measles or varicella, needs same-day specialist and health-protection assessment.
Severe headache, neck stiffness, reduced consciousness, ataxia, orchitis pain, pancreatitis symptoms or hearing change after mumps requires complication assessment.
Any suspected rubella exposure or illness involving a pregnant person requires immediate health-protection and maternity advice because fetal risk is disproportionate to maternal illness.
05Complication-directed assessment
Why
Identify pneumonia, encephalitis, bacterial skin infection, pancreatitis, orchitis or dehydration.
Interpretation and limitations
Use blood tests, cultures, imaging, lumbar puncture or organ-specific studies only after stabilisation and according to the clinical syndrome.
3Give written isolation, deterioration and vulnerable-contact advice, including when and how to seek review without exposing a waiting room.
03High-risk diseaseEscalate varicella or measlesEscalationA neonate, immunocompromised child or severe respiratory, neurological or disseminated phenotype is present.+
1Admit or arrange urgent specialist assessment in appropriate isolation and obtain infection, paediatric and critical-care advice.
2Investigate visceral and bacterial complications while supporting oxygenation, circulation, glucose and hydration.
3Start the specialist therapeutic antiviral or antimicrobial regimen promptly when indicated; prophylaxis dosing is not treatment dosing.
04ExposureUse time-dependent prophylaxisA susceptible child or vulnerable contact has a significant measles or varicella exposure.+
1Contact health protection urgently to confirm exposure significance, susceptibility, immune status and exact first exposure date.
2For measles, use eligible MMRV or MMR ideally within 72 hours, or the specified immunoglobulin route within 6 days for defined vulnerable contacts.
3For varicella, give susceptible immunosuppressed contacts oral aciclovir or valaciclovir on days 7–14; use the current neonatal immunoglobulin exceptions when applicable.
05RecoveryRestore prevention and follow-upAcute infection has resolved or a diagnosis is confirmed.+
1Complete public-health exclusion and contact actions and document laboratory status and complications.
2Arrange hearing, neurological, respiratory, skin or reproductive follow-up when the disease phenotype requires it.
3Review the whole immunisation record and offer outstanding cohort-appropriate MMRV or MMR doses after the relevant illness and treatment intervals.
Key medicines and prescribing safety3 treatments · regimens, roles and cautions+
Supportive analgesia and comfort treatment for uncomplicated viral illness while hydration and red flags are monitored.
Paracetamol
Give the current product-label or BNFC age-and-weight oral dose at the stated interval and maximum, only while fever, parotid pain or skin discomfort causes distress.
Check age, weight, liver disease and all combination products. Do not use temperature response to judge severity, and never give aspirin to a child under 16.
Current preferred post-exposure protection for immunosuppressed contacts and selected other high-risk groups.
Aciclovir or valaciclovir varicella prophylaxis
For a susceptible immunosuppressed child after significant exposure, give the current UKHSA age-and-weight oral prophylaxis regimen from day 7 through day 14 after the first exposure day.
This off-label prophylaxis requires exposure, susceptibility and immune-risk assessment. Adjust for renal function and hydration; active rash requires therapeutic dosing and severe disease may require intravenous aciclovir.
Therapeutic antiviral treatment for children at high risk of visceral progression or with established severe disease.
Intravenous aciclovir
For severe, disseminated, neonatal or immunocompromised varicella, start the current BNFC intravenous age-and-weight treatment regimen promptly under paediatric infection advice, with duration determined by clinical response.
Ensure adequate hydration, calculate renal adjustment, monitor creatinine and urine output and use correct infusion technique to reduce crystalluria and kidney injury.