for National Geographic News
Part one of a three-part series on the resurgence of killer diseases once thought wiped out
Recent outbreaks of the measles in the United States prove that many remain at risk from the disease, which had once been all but eliminated in the U.S.
The outbreaks appear to be the result of two factors, experts say: the use of ineffective vaccines on some children born in the mid-1960s, and a more recent reluctance among some Americans to get vaccinated.
Health officials in Boston, Massachusetts, found out last spring just how easily an outbreak can unfold.
In May a computer programmer contracted the measles in India and brought the disease back to his workplace in Boston's Hancock Tower office building.
Over the next two months 15 people contracted the disease from working in the building or through contact with infected people.
The worker was unvaccinated, but the outbreak infected many who had been. Those victims were among the millions of Americans in their 30s and 40s who received ineffective vaccinations as children.
The outbreak proves that measles can spread quickly in a world where both people and pathogens can move about more freely than ever, says Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases in Atlanta, Georgia.
"A vaccine-preventable disease anywhere in the world can put people anywhere else in the world at risk," Schuchat said.
Vaccines have long been required in the U.S. for admission to public schools.
But several measles vaccines used in the United States between 1963 and 1968 did not offer lasting protection. Some children during this period were also vaccinated before the age of 12 months, when they may have had maternal antibodies that blocked the vaccines.
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