By Dennis Thompson
FRIDAY, September 3 (HealthDay News) -- A 7-year-old San Diego boy brought back more than souvenirs and memories from a family trip to Switzerland a couple years ago.
While there, he became infected with measles, a disease his parents had chosen not to have him vaccinated against. Upon his return to the United States, the boy unknowingly exposed 839 people to measles.
The story -- a true tale -- is the type of nightmare scenario that has spurred public health officials to campaign for the merits of vaccination in hopes that skeptical parents will understand the necessity of their children's shots.
And the outbreak wasn't even the only one of its kind that year.
"During 2008, there were literally dozens of small outbreaks where measles would be imported from another country," said Dr. Lance Rodewald, director of the immunization services at the National Center for Immunization and Respiratory Diseases, which is part of the U.S. Centers for Disease Control and Prevention. "Basically, measles is a plane ride away. That's one of the primary signs we need to remain vigilant."
Most parents, it seems, do have their children vaccinated. Immunization coverage has continued to remain high, Rodewald said, despite what he called unfounded fears and rumors that vaccines are somehow unsafe.
But the number of children being exempted from vaccination has increased and is now as high as 4.5 percent, he said.
"One of the concerns we have is that kids who are exempted tend to cluster in specific geographical areas," Rodewald said. "That's sort of a setup for vaccine-preventable diseases to spread."
This stems from what public health experts call "herd immunity," a basic principle of immunization policy: When enough children in a group have been vaccinated, they end up protecting everyone from the spread of disease.
"The fewer people in the herd who receive vaccine, the more vulnerable the rest of the population is to being exposed and contracting the diseases," explained Dr. Alanna Levine, a New York pediatrician and spokeswoman for the American Academy of Pediatrics and its Protect Tomorrow campaign for immunization.
The San Diego boy attended a charter school in which 11 percent of the children were unvaccinated for measles, according to a scientific report of the outbreak prepared for the journal Pediatrics.
The California outbreak came as a shock to many public health officials because, as Levine said, "measles was declared eliminated from the United States in 2008."
An additional 11 unvaccinated children ended up contracting measles, which can lead to life-threatening complications. That number included three babies who were too young to have received the measles vaccines. One infant spent three days in the hospital and ran a 106-degree fever.
Another outbreak occurred in New York in 2009, this one involving mumps, Levine said. An 11-year-old boy had traveled to the United Kingdom and shortly afterward went to summer camp, infecting campers and camp counselors alike. By January of this year, more than 1,500 cases of mumps had been tracked back to this single incident.
Parents who are reluctant to have their children vaccinated often cite fears that the immunizations could cause the kids to become sick. Such fears were stoked to a fever pitch a decade ago with the publication of a scientific study linking the measles, mumps, rubella (MMR) vaccine to childhood autism.
The study turned out to have been based on bad and unethical science, Levine said. And this year the British medical journal that published the study took the unprecedented step of withdrawing it. In May, the doctor who produced the study, Andrew Wakefield, was banned from practicing medicine in England.
The damage was done, however. "The fear still exists," Levine said. "The issue was raised, and even though the medical community has withdrawn studies from journals and revoked licenses, the fear still exists."
Some parents also worry that their children might be harmed by receiving so many vaccines so young in life. Levine said that's an unfounded fear because decades of medical science have gone into crafting a vaccination schedule designed to protect children as early and as safely as possible.