Duration of Fever in Measles
Fever in natural measles infection typically lasts throughout the prodromal phase (3-4 days) and peaks with rash onset, then gradually resolves over 2-3 days after the rash appears, for a total fever duration of approximately 5-7 days. 1, 2, 3
Clinical Course of Fever in Measles
The fever pattern in measles follows a characteristic biphasic course:
- Initial fever onset occurs after an incubation period averaging 10-12 days from exposure, marking the beginning of the prodromal phase 1
- Prodromal fever persists for 3-4 days alongside the classic triad of cough, coryza, and conjunctivitis 2, 3, 4
- Peak fever coincides with rash appearance, which typically emerges on day 14 after exposure (approximately 3-4 days after prodrome begins) 3, 4, 5
- Fever resolution occurs gradually over 2-3 days following rash onset 2
Key Clinical Features During Febrile Period
During the prodromal phase (days 1-4 of fever):
- High fever is accompanied by respiratory symptoms (cough, coryza) and conjunctivitis 1, 3, 5
- Koplik spots may appear on buccal mucosa, providing diagnostic opportunity before rash emerges 3, 4, 5
At rash onset (peak fever):
- The characteristic erythematous maculopapular rash begins on the face and spreads cephalocaudally 3, 5
- Fever reaches its maximum intensity at this stage 4
Important Clinical Caveats
Prolonged or recurrent fever suggests complications:
- Fever persisting beyond 2-3 days after rash onset should raise concern for bacterial superinfection (pneumonia, otitis media) or other complications 1
- Encephalitis occurs in approximately 1 per 1,000 cases and typically presents during or shortly after the acute illness with fever and neurological signs 1, 6
Contrast with vaccine-related fever:
- Post-MMR vaccination fever occurs in approximately 5% of vaccinees, beginning 5-12 days after vaccination and lasting only 1-2 days (rarely up to 5 days) 1
- This vaccine-related fever is substantially shorter and milder than natural measles infection 1
Mortality and Morbidity Context
The case-fatality rate for measles in the United States is 1-2 per 1,000 cases, with pneumonia and acute encephalitis being the most common causes of death 1. The risk for severe complications and death is greatest in infants, young children, and adults 1. In developing countries with vitamin A deficiency, case-fatality rates can reach 25% 1, 2.