Measles: Clinical Timeline and Management
Measles has an incubation period of 10-12 days from exposure to prodrome onset (14 days to rash), with patients contagious from 4 days before to 4 days after rash onset, and symptoms typically lasting 7-10 days from prodrome through rash resolution. 1
Incubation Period
- The incubation period averages 10-12 days from exposure to the onset of prodromal symptoms (fever, cough, coryza, conjunctivitis) 1
- From exposure to rash appearance, the incubation period is approximately 14 days 1
- Some sources report a range of 8-11 days for the initial incubation phase 2
Contagious Period
- Patients are contagious from 4 days before rash onset through 4 days after rash appearance 1
- Healthcare workers with measles should be excluded from work until ≥4 days following rash onset 3
- This extended contagious period before symptom recognition makes measles highly transmissible in healthcare and community settings 1
Clinical Course and Symptom Duration
Prodromal Phase (3-4 days)
- High fever, cough, coryza (runny nose), and conjunctivitis appear first 1
- Koplik's spots (white-marked enanthema on buccal mucosa) develop in two-thirds of patients, providing diagnostic opportunity before rash emergence 2, 4
- This phase lasts approximately 3-4 days before rash onset 5
Exanthem Phase (4-7 days)
- The characteristic maculopapular rash appears 3-4 days after fever onset, initially on the face and behind the ears, then spreads cephalocaudally (downward) 5, 4
- Rash appearance coincides with peak symptom severity 5
- The rash becomes more confluent as it spreads and typically lasts 4-7 days before fading
Post-Vaccination Symptoms
- After MMR vaccination, mild measles-like symptoms may occur 5-14 days post-vaccination due to limited viral replication 6
- Vaccine-related fever (≥103°F) develops in 5-15% of vaccinees between days 5-12 after vaccination, lasting 1-2 days (rarely up to 5 days) 3
Complications and Their Timeline
- Diarrhea is the most common complication, followed by otitis media and bronchopneumonia 1
- Pneumonia is the most common cause of measles-related death 7
- Acute encephalitis occurs in approximately 1 per 1,000 cases, typically developing during or shortly after the acute illness 7, 1
- Subacute sclerosing panencephalitis (SSPE) is a rare but fatal late complication appearing years after initial infection 7
Treatment Options
Treatment is primarily supportive, as no specific antiviral therapy exists for measles 2, 5
Supportive Care
- Correction of dehydration with oral rehydration therapy 7
- Fever management and symptomatic relief 2
- Treatment of secondary bacterial infections (pneumonia, otitis media) with appropriate antibiotics 7, 5
Vitamin A Supplementation
- Vitamin A is recommended for all children with clinical measles to reduce mortality risk 7
- This is particularly critical as measles is the most important cause of blindness in children with borderline vitamin A status 2
Post-Exposure Prophylaxis
- MMR vaccine administered within 72 hours of exposure can prevent or modify disease 3
- Immune globulin (IG) 0.25 mL/kg IM (maximum 15 mL) can prevent or modify infection if given within 6 days of exposure, particularly when vaccine is contraindicated 3
- If IG is administered, observe for symptoms for 28 days (rather than 21) as IG may prolong the incubation period 3
Critical Infection Control Measures
- Exposed healthcare workers without immunity should be excluded from work days 5-21 after exposure 3
- All staff caring for measles patients should use N95 respirators regardless of immunity status due to ~1% vaccine failure rate 3
- Patients should be placed in airborne-infection isolation (negative pressure room) immediately 3
High-Risk Populations
- Infants, young children, and adults face greater risk of death than older children and adolescents 7
- Immunocompromised individuals (leukemia, lymphoma, HIV) experience more severe and prolonged infection 7
- Pregnant women have increased rates of premature labor, spontaneous abortion, and low birth weight infants 7, 1