Measles is an acute febrile rash illness caused by infection with the measles virus and is classified as a Group 2 nationally notifiable infectious disease in Korea.
It is transmitted through airborne particles, and the contagious period lasts from 4 days before the appearance of the rash to 4 days after. The incubation period ranges from 7 to 21 days, with an average of 10 to 12 days.
Clinical symptoms are typically divided into three stages: the prodromal stage, which is highly contagious; the rash stage, where symptoms peak; and the recovery stage.
Prodromal Stage: This lasts for 3 to 5 days and is characterized by fever, cough, runny nose, and conjunctivitis. A distinctive feature is the appearance of 1–2 mm grayish-white lesions inside the mouth (Koplik’s spots).
Rash Stage: This stage usually begins around 14 days (range: 7–18 days) after virus exposure, marked by the onset of skin rash. Koplik’s spots appear first, followed by a red, maculopapular (non-vesicular) rash 1–2 days later. The rash typically starts behind the ears and at the back of the neck, then spreads to the trunk, limbs, and eventually the palms and soles in a sequential pattern. The rash may merge into larger patches, and high fever often occurs for 2–3 days after the rash appears. In individuals who have received the MMR vaccine, the rash may be milder. The rash stage lasts about 5–6 days after onset and usually resolves within 7–10 days.
Recovery Stage: As the rash fades, it often leaves behind pigmentation. In rare cases, complications such as respiratory infections, diarrhea, or acute encephalitis may occur. However, such complications are uncommon in individuals with prior MMR vaccination.
All measles cases reported in Korea this year have been related to overseas importation or contact with imported cases (a 1.9-fold increase compared to the same period last year). According to the Korea Disease Control and Prevention Agency’s April 17, 2025 report, Vietnam accounted for the vast majority of cases (37 out of 39). With the ongoing rise in COVID-19 infections, continued vigilance is necessary.