Even when there are significant gains against infectious diseases, there can be reversals. In 2000, measles was considered all but eliminated in the United States. For a while, there were only about 60 cases a year, mostly brought in from overseas. Now, the number of cases and outbreaks in the United States is rising again. The Centers for Disease Control and Prevention reported Thursday that there have already been more cases this year, 288, than in any full year this century.

Measles is a highly infectious respiratory disease caused by a virus that affects young children, with fever, runny nose, cough and a distinctive rash. Infrequently, it leads to more serious complications. There have been no deaths in the United States for a while, but in 2012 measles caused an estimated 122,000 deaths worldwide. That’s far fewer than in the past, thanks to a global campaign to vaccinate more than a billion children in high-risk countries.

In the United States, a vigorous effort at immunization in recent years brought measles almost to a standstill. After an epidemic from 1989 to 1991 resulted in 55,000 cases and more than 100 deaths, largely because of lack of immunization among poor and uninsured children, a federal program approved in 1994, Vaccines for Children, resulted in much wider coverage. More than 90 percent of the children in the United States are immunized.

Most of the recent measles cases in the United States arrived with travelers. For example, California reported 58 cases from January through April 18 this year, the highest number for that period in 19 years. According to the CDC, 93 percent of the California cases are linked to importation of the disease. The Philippines has seen an ongoing outbreak.

Sometimes a single traveler can ignite a wildfire of infections. In 2013, a 17-year-old who had not been vaccinated returned to an orthodox Jewish community in Brooklyn from the United Kingdom, leading to an outbreak that affected 58 people; most were in three extended families that had declined the measles vaccine. This year, an outbreak in Ohio has reached 68 cases, apparently sparked by Amish missionaries, unvaccinated, who had visited the Philippines.

The measles vaccine has been in use for half a century and is safe, inexpensive and effective. Some parents suspicious of vaccines have decided against immunization; in other cases, people are simply ignorant of the risks of inaction. Not all 50 states have the toughest immunization laws and standards. Thus, in some vulnerable pockets of the United States, a single person can touch off an outbreak. A nation’s borders provide no ironclad defense against viruses and bacteria. But measles can be stopped with comprehensive and proper immunization.

Editorial by The Washington Post

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