Measles Basics

Signs and symptoms of measles infection

Measles typically begins with a mild to moderate fever accompanied by cough, coryza, and conjunctivitis
(prodromal phase). Some cases also report diarrhea, nausea, and vomiting. Two to three days later,
Koplik's spots, a characteristic sign of measles, may appear. At this time the fever spikes, often to >104°F,
and a red blotchy maculopapular rash appears, usually first on the face, along the hairline, and behind
the ears. This rash spreads downward to the trunk and then to the arms and legs. In approximately one
week, the rash fades in the same sequence that it appeared. Atypical rashes have been reported.
Complications of measles, including otitis media, bronchopneumonia, and laryngotracheobronchitis
(croup) occur commonly in young children and immunocompromised hosts.

Measles exposure
Sharing the same airspace with a person infectious with measles e.g., same classroom, home, clinic
waiting room, etc., or being in these areas up to 2 hours after the infectious person has left the area is
considered to be a measles exposure. Exposures occur during the case’s infectious period, which starts
four days before rash onset through four days after rash onset (day of rash onset is day 0).
No minimum duration has been established for an exposure, but it is presumed that exposures that are
longer in duration and/or face to face are more likely to result in measles transmission than brief,
transient exposures.

Measles infectious period
From four days before rash onset through four days after rash onset (day of rash onset is day 0).
Immunocompromised patients who may have prolonged excretion of the virus in respiratory tract
secretions can be contagious for the duration of the illness. Suspected or confirmed measles cases
should be isolated during their infectious period.

Measles incubation period
From exposure to onset of prodromal symptoms is generally 8–12 days. The average interval between the
appearance of rash in the index case and rash in secondary cases is 14 days (range 7 -21 days).