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Epidemiology of measles
Medical expert of the article
Last reviewed: 04.07.2025
Measles was the most common infection in the world before vaccination and was found everywhere. Increases in incidence every 2 years are explained by the accumulation of a sufficient number of people susceptible to measles. Measles incidence was observed all year round with an increase in autumn, winter and spring.
The source of infection is only a sick person. The patient is most contagious during the catarrhal period and on the first day of the rash. From the 3rd day of the rash, contagiousness decreases sharply, and after the 4th day the patient is considered non-contagious.
The infection is transmitted by airborne droplets. When coughing or sneezing, the measles virus is released into the environment with mucus droplets from the upper respiratory tract and can be spread by the air current in closed rooms over significant distances - to neighboring rooms and even through corridors and stairwells to other apartments. It is possible to carry the measles virus from the lower to the upper floor through the ventilation and heating system. Transmission through a third party is very rare, since the measles virus quickly dies outside the human body.
The contagious index is 95-96%. When measles is brought to places where there have been no measles epidemics for a long time and vaccination has not been carried out, almost the entire population becomes ill, since susceptibility to the pathogen remains until old age.
After measles, a stable immunity is created, repeated diseases are rarely observed. In the pre-vaccination period, almost 90% of people had measles before the age of 10. Most often, children aged 1 to 4-5 years get measles, up to 6 months rarely get measles. Children under 3 months, as a rule, do not get measles, which is explained by the passive immunity received from the mother. After 3 months, passive immunity decreases sharply, and after 9 months it disappears in all children. If the mother has not had measles, the child can get it from the first day of life. Intrauterine infection is possible if the mother got measles during pregnancy. In recent years, due to the mass immunization of children against measles, adults who have not been vaccinated or have lost immunity are more often sick.
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