What are the clinical signs and symptoms of measles in children?

Clinical Signs and Symptoms of Measles in Children

Measles in children presents with a characteristic two-phase illness: a prodrome of high fever (≥38.3°C), cough, coryza (runny nose), and conjunctivitis ("the three Cs"), followed 2-4 days later by a maculopapular rash that begins on the face and spreads downward to the trunk and extremities. 1

Incubation Period and Timeline

• The incubation period averages 10-12 days from exposure to prodrome and 14 days from exposure to rash (range: 7-18 days). 2, 1
• Children are contagious from 4 days before rash onset through 4 days after rash appears. 2, 1

Prodromal Phase (Initial Symptoms)

The prodrome typically lasts 2-4 days and includes:

• High fever (≥38.3°C or 101°F), often the first symptom 1, 3
• Cough - persistent and worsening 2, 1
• Coryza (runny nose) - profuse nasal discharge 2, 1
• Conjunctivitis ("pink eye") - red, watery eyes with photophobia 2, 1
• Koplik spots - small white spots with red halos on the buccal mucosa (inside the cheeks), appearing 2-3 days before the rash and considered pathognomonic (uniquely diagnostic) for measles 2, 1, 3

Rash Phase

• The maculopapular rash appears 2-4 days after prodrome onset, typically when fever peaks again 1, 3
• Rash begins on the face (particularly at the hairline and behind the ears) and spreads downward (cephalocaudal progression) to the trunk and extremities over 3 days 1, 4
• The rash is erythematous (red), maculopapular (flat and raised spots), and becomes more confluent (merges together) on the face and upper body 3, 4
• Rash typically lasts ≥3 days 1

Common Complications in Children

Measles is not a benign illness—complications occur frequently:

• Diarrhea - the most common complication 2, 1
• Otitis media (middle ear infection) - second most common 2, 1
• Bronchopneumonia - third most common, and a leading cause of death 2, 1
• Encephalitis - occurs in approximately 1 per 1,000 cases, often causing permanent brain damage and mental retardation 2, 1
• Death - occurs in 1-2 per 1,000 reported cases in the United States, primarily from pneumonia and encephalitis 2, 1

High-Risk Populations

Certain children face greater risk of severe disease and death:

• Infants and young children (especially <12 months) have higher mortality rates 2, 1
• Immunocompromised children (HIV infection, leukemia, lymphoma, immunosuppressive therapy) may develop severe, prolonged infection that can occur without the typical rash and may shed virus for weeks 2, 1
• Malnourished children - particularly those with vitamin A deficiency, who are at risk for blindness 5

Important Clinical Pitfalls

• Do not dismiss measles in vaccinated children—approximately 5% of children who received a single vaccine dose can still develop measles due to primary vaccine failure 2
• Immunocompromised children may present atypically without the characteristic rash, making diagnosis more challenging 2, 1
• Koplik spots disappear quickly (usually within 1-2 days of rash onset), so their absence does not rule out measles 1
• Subacute sclerosing panencephalitis (SSPE) is a rare but fatal late complication that appears years after infection, causing progressive neurological deterioration; widespread vaccination has essentially eliminated SSPE in the United States 2, 1

When to Suspect Measles

Suspect measles in any child presenting with:

• High fever PLUS the "three Cs" (cough, coryza, conjunctivitis) 1, 3
• Followed by a cephalocaudal-spreading maculopapular rash 1, 4
• Especially with travel history to endemic areas or exposure to unvaccinated individuals 6
• Presence of Koplik spots (when visible) is virtually diagnostic 2, 1