Public Health

The origin of measles is thought to have been zoonotic, evolving from Rinderpest (an infectious viral disease found in cattle, bison, and other hooved animals). A precursor to measles began sporadically infecting humans as early as the 4th Century BC, and over time evolved to become a distinct virus that infected humans.

The first systematic description of measles, and its distinction from smallpox and chickenpox, is credited to the Persian physician Muhammad ibn Zakariya al-Razi (860–932), who published The Book of Smallpox and Measles. Sometime between AD 1100 and 1200, the measles virus fully diverged from rinderpest, becoming a distinct virus that infects humans. It was at the time that medieval European cities had grown to a size to sustain an epidemic (population >500,000).

In 1757, Francis Home, a Scottish physician, demonstrated that measles is caused by an infectious agent in the blood of patients.

Measles is now an endemic disease globally, meaning that it is continually present in the population and resistance is through either vaccination or prior infection. In Measles-naive (not previously exposed to measles) populations, exposure can be devastating.

Measles is estimated to have killed about 200 million people worldwide between the years of 1855 and 2005.

Measles in the United States

In 1912, measles became a nationally notifiable disease in the United States. In the first decade of reporting, an average of 6,000 measles-related deaths were reported each year.

In the decade before 1963, when a vaccine became available, nearly all children got measles by the time they were 15 years of age.

Prior to 1963, Measles annually accounted for:

•  3 to 4 million people infected
  • An average of nearly 550,000 cases were reported annually, however most cases were not reported
• 400 to 500 deaths
• 48,000 hospitalizations
• 1,000 cases of measles-induced encephalitis (swelling of the brain)

Measles Elimination in the United States

In 1978, the CDC set a goal to eliminate measles from the United States by 1982. Although this goal was not met, widespread use of measles vaccine drastically reduced the disease rates. By 1981, the number of reported measles cases was 80% less compared with the previous year.

A measles outbreak in 1989 among vaccinated school-aged children prompted the recommendation of a second dose of the MMR vaccine for children. Following widespread implementation of this recommendation and improvements in first-dose MMR vaccine coverage, reported measles cases declined even more.

Elimination

The World Health Organization (WHO) defines measles elimination as “the absence of endemic measles virus transmission in a defined geographical area (e.g. region or country) for at least 12 months in the presence of a surveillance system that has been verified to be performing well.”

Measles was declared eliminated (absence of continuous disease transmission for greater than 12 months) from the United States in 2000. This was thanks to a highly effective vaccination program in the United States, as well as better measles control in the Americas region.

The United States has maintained measles elimination status for almost 20 years. If a measles outbreak continues for a year or more, the United States could lose its measles elimination status.