Measles: Contemporary considerations for the emergency physician

**Background:** Measles (rubeola) is a highly contagious acute febrile viral illness that was declared eliminated from the United States in 2000. However, due to falling vaccination rates—exacerbated by COVID-19 disruptions—measles cases have resurged. In 2019, 1274 cases were confirmed in 31 states, the highest since 1992. Globally, there were 9 million cases and 148,000 deaths in 2021. The virus is transmitted via airborne droplets and is infectious from 4 days before to 4 days after rash onset. Measles causes immunosuppression lasting weeks to months, increasing susceptibility to secondary infections.

**Methods:** This is a narrative review article summarizing contemporary knowledge for emergency physicians. It synthesizes data from CDC reports, WHO data, and published studies on measles epidemiology, pathophysiology, clinical presentation, diagnosis, treatment, and prevention. No original data collection or statistical analysis was performed.

**Key Results:** The incubation period is 7–21 days (average 14 days). Prodromal symptoms include high fever, malaise, and the 3 Cs (cough, conjunctivitis, coryza). Koplik spots (white/grey spots on buccal mucosa) are pathognomonic and appear ~48 hours before rash. The rash is red, blotchy, maculopapular, starting on the face and spreading downward, lasting 5–6 days. Complications occur in up to 40% of patients, with higher risk in immunocompromised, pregnant, malnourished, or very young/old patients. Otitis media is most common; pneumonia is the most common severe complication and leading cause of death. Neurologic complications include seizures (<1% of children), acute encephalitis (1 in 1000, mortality 10–15%), and subacute sclerosing panencephalitis (rare, fatal, occurs 5–10 years post-infection). Diagnosis is confirmed by RT-PCR (nasopharyngeal/oropharyngeal swabs) and serology (IgM/IgG). Treatment is supportive; vitamin A is recommended for all children with acute measles (200,000 IU for ≥12 months, 100,000 IU for 6–11 months, 50,000 IU for <6 months, daily for 2 days). Post-exposure prophylaxis includes MMR vaccine within 72 hours for susceptible individuals, or intramuscular immunoglobulin within 6 days for infants <6 months, severely immunocompromised, and unvaccinated pregnant women.

**Clinical Implications:** Emergency physicians must maintain a high index of suspicion for measles in patients with fever, cough, and rash, especially if unvaccinated or with recent travel. Immediate airborne precautions, notification of infection control and public health authorities, and appropriate testing (RT-PCR + serology) are essential. Supportive care and vitamin A administration can reduce morbidity and mortality. Vaccination (MMR, 2 doses) is the cornerstone of prevention, and emergency physicians should counsel patients and provide PEP when indicated. Special attention is needed for pregnant, immunocompromised, and pediatric patients, who are at higher risk for severe outcomes.