Measles is a highly contagious, vaccine-preventable viral illness caused by the measles virus (family Paramyxoviridae) that classically presents with fever, the "three Cs" (cough, coryza, conjunctivitis), and a cephalocaudal maculopapular rash. [1-2] Approximately 25% of patients require hospitalization, and complications occur in ~30% of cases. [1][3] The following figure illustrates the clinical features and disease timeline:
1. History
- Key HPI questions: Onset and duration of fever, rash characteristics and progression (face → trunk → extremities), presence of cough, runny nose, red/watery eyes, oral lesions
- Symptom characterization: Prodrome of 2–4 days with high fever (up to 40.6°C/105°F), malaise, and the three Cs, followed by rash onset 3–5 days later [2-3]
- Timing/triggers: Incubation period averages 10–14 days (range 7–23) from exposure to prodrome; rash appears ~14 days post-exposure [1][3]
- Associated symptoms: Diarrhea (early, may persist up to 1 month), photophobia, anorexia, malaise [1]
- Important negatives: Vaccination history (number of MMR doses and dates), recent international travel or travel to outbreak areas, known measles exposure within 21 days, immunocompromised state [4-5]
2. Alarm Features
- Respiratory distress — tachypnea, hypoxia, crackles (pneumonia is the most common cause of measles hospitalization and death) [1]
- Altered mental status, seizures, focal neurologic deficits → suspect encephalitis (~1 per 1,000 cases, 20% mortality) [2][6]
- Severe dehydration from persistent diarrhea/poor oral intake
- Signs of secondary bacterial sepsis — persistent high fever after rash onset, toxic appearance
- Corneal ulceration/visual changes — especially in vitamin A–deficient patients [6]
- Immunocompromised patients — may lack rash entirely, at risk for giant-cell (Hecht's) pneumonia (often fatal) and measles inclusion-body encephalitis (100% mortality) [1-2]
- Pregnancy — risk of spontaneous abortion, premature labor, maternal respiratory complications [6]
3. Medications
- No approved antiviral therapy exists for measles [1-2]
- Vitamin A (AAP/WHO-recommended, age-based dosing — see Treatment Plan below) — reduces mortality by 34–50% in children [1][7]
- Ribavirin — shows in vitro activity; not FDA-approved for measles; has been used off-label in severe/immunocompromised cases [4][8]
- Antibiotics — only if secondary bacterial infection (pneumonia, otitis media, sepsis) is identified; not recommended empirically [2]
- Antipyretics — acetaminophen or ibuprofen for fever/discomfort
- Contraindicated: Aspirin in children (Reye syndrome risk); high-dose vitamin A in pregnancy (teratogenic) [5]
- Post-exposure prophylaxis (PEP): MMR vaccine within 72 hours of exposure, or immunoglobulin (IG) within 6 days for those who cannot receive vaccine (infants <6 months, pregnant women, immunocompromised) [5-6]
4. Diet
- Maintain adequate hydration — oral rehydration solutions for mild dehydration; IV fluids if unable to tolerate PO or severe diarrhea
- Small, frequent, soft meals during acute illness (stomatitis may limit intake)
- Vitamin A–rich foods during recovery (eggs, dairy, orange/yellow vegetables) — though pharmacologic supplementation is the priority acutely
- No specific dietary restrictions; focus on caloric maintenance to prevent measles-associated malnutrition [1]
5. Review of Systems
- HEENT: Eye redness/discharge, photophobia, oral lesions (Koplik spots), ear pain/discharge, sore throat
- Respiratory: Cough (barking vs. productive), dyspnea, chest pain
- GI: Diarrhea (frequency, volume), vomiting, abdominal pain, oral intake
- Neurologic: Headache, confusion, seizures, focal weakness
- Constitutional: Fever pattern, weight loss, fatigue
- Skin: Rash onset location, spread pattern, pruritus, desquamation
6. Collateral History and Family History
- Vaccination records of patient and household contacts — critical for determining immunity and PEP eligibility [5]
- Exposure history: Daycare, school, healthcare facility, travel (especially international), contact with known cases
- Household contacts who are immunocompromised, pregnant, or unvaccinated infants — high-risk for severe disease
- Immigration history — recent arrival from endemic areas increases pre-test probability [2]
- Community outbreak status — check with local/state health department
7. Risk Factors
- Unvaccinated or incompletely vaccinated status (single most important risk factor) [5]
- Age: <5 years and >20 years at highest risk for complications [2][4]
- Immunocompromised: HIV/AIDS, active chemotherapy, organ transplant recipients, congenital immunodeficiency [2]
- Pregnancy [4][6]
- Vitamin A deficiency and malnutrition [1][6]
- International travel or contact with travelers from endemic regions [4]
- Born between 1957–1989 with only one MMR dose (suboptimal immunity)
8. Differential Diagnosis
- Rubella — milder prodrome, postauricular/suboccipital lymphadenopathy, shorter rash duration, no Koplik spots [2]
- Parvovirus B19 (fifth disease) — "slapped cheek" rash, reticular lace-like rash on extremities, no conjunctivitis [2]
- Roseola (HHV-6) — rash appears after fever resolves (opposite of measles) [9]
- Scarlet fever — sandpaper-textured rash, strawberry tongue, pharyngitis, Pastia lines [9]
- Kawasaki disease — prolonged fever, conjunctival injection without exudate, mucositis, extremity changes, lymphadenopathy (children <5 years)
- Drug reaction — temporal relationship to medication, eosinophilia
- Dengue/Zika/Chikungunya — travel to endemic areas, arthralgia, thrombocytopenia [6]
- Acute HIV seroconversion — morbilliform rash, oral ulcers, lymphadenopathy [10]
- Meningococcemia — cannot-miss; petechial/purpuric rash, rapid deterioration [11]
9. Past Medical History
- Prior measles infection (confers lifelong immunity)
- Number and dates of MMR vaccinations
- Immunosuppressive conditions or medications (biologics, chemotherapy, chronic steroids)
- History of vitamin A deficiency or malabsorption syndromes
- Pregnancy status in women of childbearing age
- Prior episodes of febrile exanthems
- Chronic lung disease (increases pneumonia risk)
10. Physical Exam
- Vitals: High fever (often ≥40°C/104°F), tachycardia; assess for tachypnea/hypoxia (pneumonia)
- HEENT:
- Koplik spots — small bluish-white plaques on buccal mucosa (pathognomonic; present in 60–70% of cases, appear 1–2 days before rash) [1-2][4]
- Bilateral non-purulent conjunctivitis
- Rhinorrhea, pharyngeal erythema
- Otoscopic exam for otitis media
- Skin: Erythematous maculopapular rash starting at hairline/face → trunk → extremities; may become confluent on face/upper body; initially blanching, later brownish with desquamation [2][4]
- Lungs: Crackles, rhonchi, decreased breath sounds (pneumonia)
- Neuro: Mental status, meningeal signs, focal deficits (if encephalitis suspected)
- Lymph nodes: Generalized lymphadenopathy may be present
11. Lab Studies
- Measles-specific IgM (serum) — sensitivity 83–98.8%, specificity 93.7–100%; may be negative in first 72 hours after rash onset; repeat if initially negative [2][4][12]
- Measles RT-PCR (NP or throat swab ± urine) — sensitivity 94%, specificity 99%; detectable ~3 days after rash onset; preferred early test [2][4]
- Urine PCR — adding urine to NP/throat swab improves sensitivity [4-5]
- CBC — leukopenia (especially lymphopenia) is common; may see secondary leukocytosis with bacterial superinfection
- CMP/BMP — assess hydration status, electrolytes (diarrhea/dehydration)
- Blood cultures — if secondary bacterial infection suspected
- CRP/procalcitonin — to help differentiate viral vs. bacterial complications
- Vitamin A levels are not routinely needed before supplementation [3]
12. Imaging
- Chest X-ray — indicated if respiratory distress, hypoxia, or clinical suspicion for pneumonia; findings may include interstitial infiltrates, lobar consolidation, or hilar lymphadenopathy [6]
- CT chest — rarely needed; consider for severe or atypical pneumonia in immunocompromised patients
- MRI brain — indicated if neurologic symptoms; acute disseminated encephalomyelitis (ADEM) shows T2/FLAIR hyperintensities in white matter [6]
- Imaging is unnecessary in uncomplicated measles
13. Special Tests
- CDC case definition: Generalized maculopapular rash + fever ≥38.3°C + cough, coryza, or conjunctivitis — sensitivity 75–90%, but low positive predictive value in low-incidence settings [2]
- Viral genotyping — performed by public health labs for epidemiologic tracking; not needed for clinical management [2]
- IgG avidity assay — distinguishes primary infection from secondary immune response in previously vaccinated individuals [6]
- CSF measles antibodies — indicated if SSPE suspected; compare CSF:serum ratio to confirm intrathecal synthesis [12]
- Lumbar puncture — if encephalitis suspected
14. ECG
- Myocarditis is a rare complication of measles; obtain ECG if chest pain, new heart failure symptoms, or unexplained tachycardia
- Look for: ST-segment changes, low voltage, conduction abnormalities, arrhythmias
- Routine ECG is not indicated in uncomplicated measles
15. Assessment
Clinical summary: Measles is one of the most contagious human diseases (R₀ = 12–18), transmitted via airborne droplets and remaining infectious in air for up to 2 hours. Patients are contagious from 4 days before to 4 days after rash onset. [1-2]
Severity stratification
- Uncomplicated: Self-limited; fever + rash + three Cs resolving within 7 days of rash onset [2]
- Complicated: Pneumonia (1–6%), otitis media (7–9%), diarrhea (8–10%), encephalitis (~1/1,000), death (~1–3/1,000 in developed countries) [1-2]
- Atypical presentations: Modified measles in previously vaccinated (milder/absent symptoms); absent rash in immunocompromised [6]
Immune amnesia: Measles causes immunosuppression lasting 2–3 years, increasing susceptibility to secondary infections — a critical counseling point. [4]
16. Treatment Plan
Initial stabilization
- Immediate airborne isolation (negative-pressure room if available; N-95 mask for all staff) [5][13]
- IV access and fluid resuscitation if dehydrated
- Supplemental O₂ if hypoxic
Vitamin A supplementation (AAP/WHO — 2 oral doses on consecutive days): [2-3][7]
A third age-specific dose at 2–4 weeks if clinical signs of vitamin A deficiency (xerophthalmia, Bitot spots). [2-3] Avoid high-dose vitamin A in pregnancy. [5]
Supportive care
- Antipyretics (acetaminophen/ibuprofen) for fever
- Oral or IV rehydration for diarrhea/dehydration
- Antibiotics only for confirmed secondary bacterial infections (pneumonia, otitis media, sepsis) [2]
Post-exposure prophylaxis for contacts: [5]
- MMR vaccine within 72 hours of exposure (for eligible contacts ≥6 months without evidence of immunity)
- Immunoglobulin (IG) within 6 days for infants <6 months, pregnant women, and immunocompromised individuals who cannot receive live vaccine
Mandatory reporting: Notify local/state health department immediately upon clinical suspicion — do not wait for lab confirmation. [2][5]
17. Disposition
Admission criteria
- Respiratory distress, hypoxia, or pneumonia
- Severe dehydration or inability to tolerate oral fluids
- Neurologic symptoms (altered mental status, seizures)
- Immunocompromised patients
- Pregnant patients with complications
- Infants <12 months with moderate-to-severe illness
- Social concerns (inability to isolate at home)
Discharge criteria
- Clinically stable, tolerating oral fluids, no respiratory distress
- Able to self-isolate at home for 4 days after rash onset
- Reliable follow-up arranged
Observation indications
- Borderline cases with mild dehydration or early respiratory symptoms
- Young children (<5 years) or adults (>20 years) given higher complication rates
Specialist consultation triggers
- Pulmonology/ICU for severe pneumonia or respiratory failure
- Neurology for encephalitis or seizures
- Ophthalmology for keratitis or corneal ulceration
- Infectious disease for immunocompromised patients
- OB/GYN for pregnant patients [4][6]
18. Follow Up / Return Precautions
Follow-up timing
- Primary care follow-up within 48–72 hours of ED discharge
- Recheck at 1–2 weeks to assess for late complications (pneumonia, otitis media)
- Immunocompromised patients require closer surveillance
Return immediately for
- Worsening or new-onset difficulty breathing, chest pain
- Persistent high fever (>5 days after rash onset) or fever recurrence after initial improvement
- Confusion, severe headache, seizures, neck stiffness
- Inability to keep fluids down, signs of dehydration (decreased urine output, dry mucous membranes)
- Eye pain, vision changes, or purulent eye discharge
- Ear pain or drainage
Patient counseling
- Isolation: Remain home and avoid contact with others for 4 days after rash onset [2]
- Notify anyone who may have been exposed (especially unvaccinated, pregnant, immunocompromised contacts)
- Expected course: fever resolves 2–3 days after rash onset; rash fades over 5–7 days in order of appearance; full recovery in uncomplicated cases within ~7–10 days [2]
- Immune amnesia — increased susceptibility to other infections for up to 2–3 years; ensure all other vaccinations are up to date [4]
- Ensure household contacts have evidence of immunity or receive PEP [5]
References
1. Measles 2025. — Do LAH, Mulholland K. The New England Journal of Medicine. 2025.
2. Measles. — Strebel PM, Orenstein WA. The New England Journal of Medicine. 2019.
3. Measles (Rubeola). — James L. Goodson and Thomas D. Filardo CDC Yellow Book. 2025.
4. Measles. — Stoneman EK. The Journal of the American Medical Association. 2025.
5. Expanding Measles Outbreak in the United States and Guidance for the Upcoming Travel Season. — United States Centers for Disease Control and Prevention (2025). 2025.
6. Measles. — Hübschen JM, Gouandjika-Vasilache I, Dina J. Lancet. 2022.
7. Measles and Measles Vaccination: A Review. — Bester JC. JAMA Pediatrics. 2016.
8. Acute Management of Measles: A Systematic Review of Therapeutic Strategies. — Kaur A, Alaribe U, Varon J, Hassaan S, Halma M. Antiviral Research. 2026.
9. Common Skin Rashes in Children. — Allmon A, Deane K, Martin KL. American Family Physician. 2015.
10. Post-Travel Dermatologic Conditions. — Karolyn A. Wanat and Scott A. Norton CDC Yellow Book. 2025.
11. Clinical Features, Diagnosis, and Management of Enterovirus 71. — Ooi MH, Wong SC, Lewthwaite P, Cardosa MJ, Solomon T. The Lancet. Neurology. 2010.
12. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). — Miller JM, Binnicker MJ, Campbell S, et al. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2024.
13. An Update and Review of Measles for Emergency Physicians. — Alves Graber EM, Andrade FJ, Bost W, Gibbs MA. The Journal of Emergency Medicine. 2020.