A resurgence of measles in Europe was blamed Thursday for a spike in cases in the United States, raising concern about parents' refusal to vaccinate children against the highly contagious virus.
After a decade of near total US elimination of measles, due in large part to blanket immunization of children, a surge of 175 US cases have been documented so far this year, experts said.
That number is almost triple the average 60 cases of US measles per year over the last decade, said the findings of a government study published in the Journal of the American Medical Association.
And Europe was the source for almost half (25) of the 52 measles cases that were classed as direct importations from abroad this year, a CDC spokesman told AFP.
They include six cases linked to Germany, four to Britain, four to Poland and two to Italy.
"We are getting cases from the UK, from Spain, from France, not just from the resource-poor countries," said Samuel Katz, Chair Emeritus of Pediatrics at Duke University Medical School, at a news conference.
"So the failure to eliminate measles in these countries has been a critical part of the importation into the United States," said Katz, who was a key player in the development of the measles vaccine, which was approved in 1963.
He said the rise in cases in Europe and beyond is "in great part due to vaccine hesitancy."
EU countries documented more than 8,100 cases of measles from April 2012 to March 2013, according to the European Center for Disease Prevention and Control.
The trend against vaccination threatens to cause more outbreaks, reviving memories of the days when nearly every child in America was sickened by it and hundreds died each year.
"It is not a failure of the vaccine. It is a failure to vaccinate," said US Centers for Disease Control and Prevention director Tom Frieden, who briefed reporters on the research.
"Around 90 percent of the people who have had measles in this country were not vaccinated."
The United Kingdom and Italy were among a handful of countries linked to causing 20 or more cases of measles in the United States from 2001 to 2011.
Others were China, Japan, India and the Philippines.
The concerns come as the United States marked a milestone of success against measles, documenting fewer than one case per million from 2001 to 2011, said the JAMA study.
"The United States is the most populous country to have documented elimination of endemic measles," it said.
But while measles has vanished from the Western hemisphere, it remains a leading cause of death among children worldwide, especially in parts of Africa and Asia, and kills as many as 18 children per hour around the globe.
Malnourished children are particularly at risk for complications of measles, which typically causes fever, rash, eye infection and white spots in the mouth.
More serious complications include blindness, pneumonia, brain damage and severe dehydration.
From 2001 through 2011, there were 911 total cases of measles reported in the United States.
An editorial in JAMA by Mark Grabowsky, of the Office of the Secretary General's Special Envoy for Financing the Health Millennium Development Goals and for Malaria, called the vaccine efforts a "triumph of public health."
But, he warned, "the greatest threat to the US vaccination program may now come from parents' hesitancy to vaccinate their children."
"Although this so-called vaccine hesitancy has not become as widespread in the United States as it appears to have become in Europe, it is increasing."