Overview
Recognise three notifiable viral infections, isolate suspected measles immediately, protect vulnerable contacts and pregnancy, and use the current UK immunisation schedule accurately.
Measles virus is transmitted by aerosols and is exceptionally contagious. Replication in respiratory epithelium and lymphoid tissue produces viraemia, transient immune suppression and a T-cell-mediated rash. The clinical sequence matters: prodromal fever with cough, coryza and conjunctivitis precedes Koplik spots and the cephalocaudal exanthem. Pneumonitis and encephalitis are major acute threats, while subacute sclerosing panencephalitis is a rare delayed consequence.
Mumps virus spreads through respiratory droplets and saliva. Viraemia targets salivary glands, testes, ovaries, pancreas and central nervous system. Parotitis is recognisable but not universal, and aseptic meningitis may occur without obvious gland swelling. Post-pubertal orchitis can be intensely painful; atrophy may follow, although sterility is uncommon after unilateral disease.
Rubella virus spreads by respiratory contact and is frequently mild or subclinical after birth. Its importance is transplacental infection: early fetal infection disrupts organogenesis and can cause miscarriage or
Aetiology
Measles aerosols
Airborne morbillivirus remains suspended after an infectious person coughs or breathes, allowing rapid transmission in poorly ventilated shared spaces.
Mumps droplets
Paramyxovirus in saliva and respiratory secretions spreads through close contact, shared utensils and droplets before and after gland swelling.
Rubella respiratory spread
Rubella virus passes between people through respiratory secretions and can cross the placenta during maternal viraemia.
Immunity gaps
Missed doses, disrupted programmes and incomplete catch-up create susceptible clusters in which imported infection can produce sustained outbreaks.
Pathophysiology
- 1Measles viraemia
Respiratory replication seeds lymphoid tissue and distant organs, while the antiviral T-cell response produces rash and temporary immune suppression.
- 2Mumps gland tropism
Viraemic virus inflames salivary, gonadal and pancreatic tissue and can enter the meninges, creating organ-specific swelling and pain.
- 3Rubella placental invasion
Maternal viraemia infects placenta and fetal tissues, disrupting cell division, blood vessels and organogenesis during vulnerable early development.
- 4Live-vaccine immunity
Attenuated vaccine viruses produce humoral and cellular memory without wild-type organ invasion, substantially reducing infection, complications and onward transmission.
Clinical features and red flags
High fever with cough, coryza, red watery eyes and malaise precedes the rash; tiny white Koplik spots may appear on the buccal mucosa.
A blanching erythematous maculopapular rash begins behind the ears or at the hairline, spreads down the trunk and limbs and may become confluent.
Tender swelling elevates the ear lobe and obscures the mandibular angle, often with fever, headache, malaise and pain when chewing acidic food.
Testicular pain and swelling, meningism, encephalopathy, upper abdominal pain or hearing loss can occur with or without prominent parotitis.
Low-grade fever, fine pink rash, posterior auricular or suboccipital nodes and symmetrical arthralgia are typical, but many infections remain subclinical.
Sensorineural deafness, cataract or pigmentary retinopathy, patent ductus arteriosus, growth restriction and developmental impairment indicate fetal infection.
Investigations
- 01
Immediate clinical and exposure assessmentFirst step - Why
- Identify probable measles and vulnerable contacts before laboratory confirmation.
- Interpretation and limitations
- Record rash onset, vaccination history, travel, known exposure, pregnancy and immune status; compatible fever-rash illness still requires isolation and notification when vaccination history is incomplete or exposure is plausible.
- 02
UKHSA oral-fluid test - Why
- Confirm suspected measles, mumps or rubella through the health-protection pathway.
- Interpretation and limitations
- Arrange the supplied oral-fluid kit after notification and add throat swab, urine or other urgent diagnostic samples when the health protection team advises; do not delay control measures while awaiting results.
- 03
Measles PCR and serology - Why
- Provide rapid confirmation in severe, admitted or outbreak-associated suspected measles.
- Interpretation and limitations
- PCR from appropriate respiratory or urine samples is most useful early; IgM timing, recent vaccination and false-positive rash illnesses require laboratory and epidemiological interpretation.
- 04
Mumps PCR - Why
- Confirm mumps when parotitis or a complication is clinically suspected.
- Interpretation and limitations
- Buccal or oral-fluid PCR close to symptom onset is preferred; serum amylase is non-specific and a negative late sample does not automatically identify another cause.
Differential diagnosis
Other viral exanthem
Parvovirus B19, roseola, enterovirus and EBV can cause fever with rash but differ in sequence, distribution, exposure and targeted testing.
Bacterial parotitis
Unilateral toxic swelling, purulent Stensen-duct discharge, dehydration and neutrophilia favour bacterial infection requiring culture and antibacterial treatment.
Medication eruption
A temporally related symmetrical rash may mimic measles or rubella, but does not remove notification duty when fever and epidemiology fit.
Kawasaki disease
Persistent fever with conjunctival injection, oral change, extremity findings and lymphadenopathy requires cardiovascular evaluation rather than isolation alone.
EBV mononucleosis
Exudative pharyngitis, posterior cervical nodes, splenomegaly and atypical lymphocytosis suggest EBV, sometimes with an antibiotic-associated rash.
Management
01MEASLESIsolate and notify firstFirst stepFever with cough, coryza, conjunctivitis or a descending rash creates clinical suspicion of measles.+
- 1Keep the patient out of common waiting space, place them in an appropriate airborne isolation room and use respiratory protective equipment under local infection-control policy.
- 2Notify the proper officer or health protection team immediately, recording rash onset, vaccination, travel, exposure, pregnancy, immune status and places attended while infectious.
- 3Obtain oral-fluid and any rapid PCR samples advised by UKHSA without sending the patient through shared clinical areas or delaying treatment of complications.
- 4Assess oxygenation, hydration and neurology, admit severe disease safely, and treat bacterial superinfection or organ failure while providing supportive measles care.
02CONTACTSUse the prophylaxis windowA susceptible or uncertain contact has had a credible measles exposure
Complications
Measles pneumonitis
Primary viral lung injury or secondary bacterial pneumonia causes hypoxia, respiratory failure and death, especially in infancy or immune suppression.
Measles encephalitis
Acute brain inflammation causes seizure and neurological injury, while delayed subacute sclerosing panencephalitis produces progressive fatal neurodegeneration years later.
Mumps organ injury
Orchitis can cause testicular atrophy, while meningitis, encephalitis, pancreatitis, oophoritis and permanent sensorineural deafness occur less often.
Congenital rubella syndrome
Fetal infection causes miscarriage, deafness, cataract, pigmentary retinopathy, congenital heart disease, growth restriction and developmental impairment.
Outbreak transmission
Delayed recognition exposes healthcare settings, schools and households, causing preventable illness among infants, pregnant people and immunosuppressed contacts.
Monitoring and follow-up
- For measles, monitor oxygen saturation, work of breathing, hydration, neurological state and bacterial complications; deterioration after initial improvement can indicate secondary pneumonia.
- Trace the infectious timeline with health protection, documenting settings attended and pregnancy, infancy or immune suppression among contacts before prophylaxis windows close.
- During mumps, reassess severe testicular pain, abdominal pain, meningism, hearing change and oral intake rather than assuming all parotitis remains uncomplicated.
- After suspected rubella in pregnancy, follow the reference-laboratory and fetal-medicine plan until maternal infection and fetal risk are resolved.
- Audit two-dose vaccine completion and schedule the outstanding dose, because one dose or uncertain verbal history leaves avoidable outbreak susceptibility.
- After live vaccination, distinguish expected short-lived fever or rash from true wild-type infection using timing, exposure history and health-protection advice.
Special situations
Notification precedes proof
Measles, mumps and rubella are notified on suspicion, allowing public-health teams to protect contacts while confirmatory samples are still in transit.
Measles suppresses immunity
Transient immune dysfunction contributes to bacterial pneumonia and can erase part of established immune memory, extending morbidity beyond the visible rash.
Mumps lacks parotitis
Aseptic meningitis or orchitis can occur without obvious salivary swelling, so exposure and vaccination history remain relevant in compatible complications.
Rubella can look trivial
Mild maternal symptoms do not imply low fetal risk, particularly early in pregnancy when organogenesis is vulnerable to transplacental virus.
Vaccine products changed
Routine English childhood vaccination now uses MMRV for eligible cohorts, but older people and several catch-up situations still require MMR according to age and history.
Common pitfalls
- 01
Do not leave a suspected measles patient in a communal waiting area while taking a routine history or awaiting permission to isolate.
- 02
Do not wait for a positive oral-fluid or PCR result before notifying suspected measles, mumps or rubella and starting contact assessment.
- 03
Do not assume two vaccine names or childhood rash history proves two valid doses; check records and use the current catch-up algorithm.
- 04
Do not administer MMR or MMRV during pregnancy or substantial immune suppression, and do not confuse postpartum vaccination with treatment of maternal infection.
- 05
Do not diagnose rubella in pregnancy from rash appearance or isolated IgM because false positives can cause profound avoidable harm.
- 06
Do not treat painful mumps orchitis with antibiotics unless clinical evidence supports a bacterial epididymo-orchitis alternative.