Rash of measles cases in the U.S.

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Measles cases are being spotted across the nation once more, according to a Centers for Disease Control and Prevention (CDC) report that identified 222 reported cases of the viral infection in the U.S. in 2011. This is the highest incidence since 1996, when 508 cases were reported. A decline in vaccination compliance appears to be responsible for this latest spike.

Although 90 percent of the cases were brought into the country by foreign visitors or citizens who had traveled outside the U.S., the number of outbreaks (defined as at least three cases linked in time and place) emphasizes the havoc that can be wreaked on an insufficiently vaccinated population. Eighty six percent of those with measles were unvaccinated or did not know their vaccination status. The average age of the measles patients was 14, pointing to parental avoidance of mandated vaccines.

"Instead of herd immunity, which is what happens when the majority of a population is vaccinated," says ACSH's Dr. Ruth Kava, "some communities in this country seem to be regressing to herd vulnerability." Dr. Anne Schuchat, who directs CDC's National Center for Immunization and Respiratory Diseases, noted that there is indeed "a relationship between the decisions families make and disease rates." In addition to being vaccinated against measles when traveling abroad, anyone uncertain of their vaccination status would be best off getting another vaccination, says Schucat.

For more on this topic, an op-ed by ACSH's Dr. Gilbert Ross (co-written with Dr. Henry Miller) offers an impressive overview of why, in the case of vaccination, it's smart to go with the herd.