Americas region declared free of endemic measles

Global health authorities on Tuesday declared the Americas free of endemic measles, the first region to be so certified.

The hemisphere’s last case of endemic measles — meaning one that did not spring from an imported strain — was in 2002.

Normally, it takes three years without cases to declare a disease eradicated from a region, but in this instance it took 14 years. Experts at the Pan American Health Organization in Washington, D.C., where the announcement was made, cited several reasons for the delay: poor communication between local and national health departments in some countries, large numbers of unvaccinated mobile migrants in others, and parts of other countries that were unreachable because of fighting.

The certification process “is really hard,” said Dr. Merceline Dahl-Regis, who chaired the expert committee that made the announcement. “It’s not an easy task.” She did not name the countries that delayed the certification, but she did congratulate Brazil for working especially hard to vaccinate children and look for cases in recent years.

Despite the elimination of endemic measles, outbreaks of imported strains continue. A case of measles in the United States was reported earlier this month, for example. In December 2014, an outbreak of hundreds of cases started in California’s Disneyland and spread to several western states and then to Mexico and Canada.

The outbreak, involving a strain of measles circulating in the Philippines, was declared over in April 2015. But its rapid dissemination exposed the fact that 9 million American children were not fully vaccinated against measles and led to tightening of vaccination rules for California schoolchildren.

In February 2015, PAHO and the World Health Organization warned that vaccination rates in the United States and Brazil appeared to be “below levels needed to prevent the spread of imported cases.”

Dr. Susan Reef, a measles and rubella specialist at the Centers for Disease Control and Prevention consulting with PAHO, said that the 2015 outbreak was “a tiny issue compared to tens of thousands of cases” seen in countries where measles is endemic. Transmission in that instance was not considered endemic because it did not go on for more than a year, she said.

“That outbreak was stopped very quickly,” she said, adding that the unvaccinated Americans to whom measles spread were “a very, very tiny group.”

Measles is one of the most infectious diseases known, and its elimination has been a goal of the WHO for decades. Worldwide, cases have dropped nearly 80 percent in the last two decades, as donors began pouring money into buying vaccines for poor countries.

But 315 children worldwide still die of measles every day, said Dr. Mary Agocs, an adviser to the Red Cross.

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