What are the signs and symptoms of measles in pediatric and adult patients?

Measles Signs and Symptoms

Measles presents with a characteristic prodrome of high fever, cough, coryza (runny nose), and conjunctivitis, followed 2-4 days later by a maculopapular rash that begins on the face and spreads downward to the trunk and extremities. 1

Classic Clinical Presentation

Incubation Period

• The incubation period averages 10-12 days from exposure to prodrome onset and 14 days from exposure to rash appearance (range: 7-18 days). 1, 2

Prodromal Phase (2-4 days before rash)

• High fever (often >104°F/40°C) 1
• The "3 Cs": Cough, Coryza (runny nose), and Conjunctivitis ("pink eye") 1, 2
• Koplik spots - small white spots on a red background inside the mouth, appearing on the buccal mucosa opposite the molars; these are pathognomonic for measles and appear during the prodrome 1, 3

Rash Phase

• Erythematous maculopapular rash that begins on the face and spreads in a cephalocaudal distribution (head to toe) to the trunk and extremities 1, 3, 4
• The rash becomes more confluent as it spreads downward 3
• Rash typically appears 14 days after exposure (range: 7-18 days) 1

Complications and Their Frequencies

Common Complications

• Diarrhea - most common complication 1, 2
• Otitis media (middle ear infection) - second most common 1, 3
• Bronchopneumonia - third most common 1, 2

Serious Complications

• Encephalitis - occurs in approximately 1 per 1,000 cases 1, 2
• Death - occurs in 1-2 per 1,000 reported cases in the United States, primarily from pneumonia and acute encephalitis 1, 2
• Subacute sclerosing panencephalitis (SSPE) - a rare but fatal late complication appearing years after infection 1

Age-Specific and Risk-Based Variations

High-Risk Populations with Worse Outcomes

• Infants and young children face higher mortality risk than older children 1
• Adults experience higher complication rates, particularly pneumonia 1
• Pregnant women may experience increased rates of premature labor, spontaneous abortion, and low birth weight infants 1, 2
• Immunocompromised individuals may develop severe, prolonged infection, sometimes without the typical rash 1

Modified Presentations

• Vaccinated individuals can have milder or even no symptoms if they develop breakthrough infection 5
• Immunocompromised patients may present without the characteristic rash, making diagnosis more challenging 1

Contagious Period - Critical for Infection Control

Patients with measles are contagious from 4 days before rash onset to 4 days after rash appears, requiring immediate airborne precautions. 1, 2

Important Clinical Pitfalls

Diagnostic Considerations

• 25%-50% of rubella infections are subclinical, but measles typically presents with more pronounced symptoms 6
• The presence of conjunctivitis, cough, hoarseness, coryza, and Koplik spots strongly suggests measles rather than other exanthematous illnesses like streptococcal pharyngitis 1
• Clinically similar illnesses can be caused by parvovirus, adenoviruses, and enteroviruses, requiring laboratory confirmation 6

Laboratory Confirmation

• Diagnosis relies on detection of measles-specific IgM antibodies in serum, dried blood spots, or oral fluid 5
• RT-PCR for measles virus RNA can be performed on throat/nasopharyngeal swabs, urine, or oral fluid 1, 5
• All suspected cases must be reported immediately and laboratory confirmed 1

Mortality Context

• While the U.S. case fatality rate is 1-2 per 1,000 cases, developing countries can see rates as high as 25% 1
• Measles causes over 100,000 deaths per year worldwide, primarily among young children 7