Washington — The incidence of measles worldwide has decreased 65 percent from 2000 to 2011, according to a new survey. The number of estimated deaths from measles has also declined, by 71 percent, from 542,000 to 158,000.
A global campaign involving the U.S. Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO) and others has produced this progress. But the report released January 18 also shows an opposite trend in the short term: measles cases increased in 2011 from the year before, with large outbreaks reported in both developed and developing countries.
"Field investigations of recent measles outbreaks found most cases were among unvaccinated persons," according to a conclusion in the report from CDC, "suggesting the main underlying cause was persistent gaps in immunization coverage, despite overall increased measles vaccine coverage."
The measles vaccine was first introduced in the early 1960s. It is credited with bringing about a sharp decline in the disease in ensuing decades. The disease has become so rare in developed countries that memory of the severity of the illness has dimmed, analysts say, and a new generation of parents does not recognize the importance of vaccination.
Measles, mostly affecting children, is a highly contagious viral disease that has no specific treatment. While most people infected recover within a few weeks, malnourished or immuno-compromised people can develop serious complications, such as encephalitis, blindness or pneumonia.
WHO recommends that young children get two vaccine doses to prevent the outbreak of epidemics. With support from the Measles and Rubella Initiative -- involving CDC, WHO, UNICEF, the United Nations Foundation and the American Red Cross - the number of nations that are routinely providing the double-shot measles vaccine has risen from 97 in 2000 to 141 in 2011, according to the report.
These improving trends in measles prevention are achieved with the two-dose vaccination strategy and what the epidemiologists call "supplemental immunization activities" in regions that are able to achieve only a one-dose round of vaccination in routine care. Supplemental programs delivered vaccines to 225 million children in 2011 and more than 1 billion youngsters over the entire survey period.
The number of annually reported measles cases decreased by almost 500,000, the research found, a decline of 58 percent over the survey period. The rate of occurrence in populations decreased from 146 to 52 cases per 1 million population per year, down 65 percent. These declines - in both aggregate cases and population incidence -- occurred in all geographic regions.
The decrease in annual measles cases continued steadily from the start of the survey until 2008, when the trend reversed, and case increases emerged in various regions. "To resume progress toward achieving regional measles elimination targets," the report said, "national governments and partners are urged to ensure that these efforts receive high priority and adequate resources to achieve [Global Vaccine Action Plan] targets."