Clinical Symptoms of Measles
Measles presents with a characteristic triad of fever (≥101°F/38.3°C), generalized maculopapular rash lasting ≥3 days, and at least one of the "three Cs": cough, coryza (runny nose), or conjunctivitis 1.
Primary Clinical Features
The disease follows a predictable timeline with an incubation period averaging 10-12 days from exposure to prodrome symptoms, and 14 days from exposure to rash (range: 7-18 days) 1.
Cardinal Symptoms (The "Three Cs" Plus Fever and Rash):
- Fever ≥38.3°C (≥101°F) - typically high-grade
- Generalized maculopapular rash lasting ≥3 days that begins on the face and spreads cephalocaudally (head to toe), becoming more confluent as it progresses 2
- Cough
- Coryza (runny nose)
- Conjunctivitis (red, watery eyes)
Pathognomonic Sign:
- Koplik spots - small white spots with red halos on the buccal mucosa (inside the cheeks), appearing during the prodrome before the rash develops 2. These were observed in 43% of cases in recent data 3.
Clinical Presentation Sequence
The illness typically begins with the prodromal symptoms (fever, cough, coryza, conjunctivitis) followed 2-4 days later by the characteristic rash. The rash classically starts on the face and hairline, then spreads downward to the trunk and extremities over 3-4 days 2.
Important Clinical Variations
Immunocompromised Patients:
Measles may occur without the typical rash in immunocompromised persons, particularly those with leukemias, lymphomas, or HIV infection. These patients may shed virus for several weeks after acute illness 1.
Vaccinated Individuals:
Previously vaccinated individuals can have milder or even no symptoms if they develop breakthrough measles 4.
Common Complications to Monitor
The disease is most frequently complicated by:
- Diarrhea
- Middle ear infection (otitis media)
- Bronchopneumonia 1
Additional complications include:
- Laryngotracheobronchitis
- Stomatitis
- Secondary bacterial infections requiring antibiotic treatment 4
Serious Neurological Complications
While uncommon, these carry significant morbidity and mortality:
- Acute encephalitis: occurs in approximately 1 in 1,000 cases, with survivors often having permanent brain damage and mental retardation 1
- Acute disseminated encephalomyelitis (ADEM): occurs during or soon after acute disease 4
- Subacute sclerosing panencephalitis (SSPE): rare degenerative CNS disease appearing years after measles infection 1
- Measles inclusion body encephalitis: particularly in immunocompromised patients 4, 5
High-Risk Populations
Risk for death or severe complications is greater for:
- Infants and young children
- Adults
- Pregnant women (increased rates of premature labor, spontaneous abortion, low birth weight)
- Immunocompromised persons 1
Death occurs in 1-2 per 1,000 reported measles cases in the United States, with pneumonia and acute encephalitis being the most common causes 1.
Clinical Pitfall
Measles is infectious approximately 4 days before rash onset through 4 days after rash appearance 6. This means patients are contagious during the prodromal phase when symptoms are nonspecific, leading to potential nosocomial transmission before diagnosis. Immediate isolation is critical when measles is suspected, even before laboratory confirmation.