In 2000, public health authorities declared measles eliminated from the United States. However, so far this year, 288 cases of measles were reported to the Centers for Disease Control and Prevention (CDC) between Jan. 1 and May 23, the largest number since 1994. The cause? “The current increase in measles cases is being driven by unvaccinated people, primarily U.S. residents, who got measles in other countries, brought the virus back to the United States and spread to others in communities where many people are not vaccinated,” said Dr. Anne Schuchat, assistant surgeon general.

Measles, a serious and highly contagious respiratory illness, causes fever, runny nose, cough, and a distinctive rash all over the body. Most common in children, adults also risk infection with the virus, especially if they have never been vaccinated. About one out of 10 children with measles also gets an ear infection, and up to one out of 20 comes down with pneumonia. For every 1,000 children who get measles, one or two will die. To prevent measles, CDC recommends the MMR vaccine.

Referred to as anti-vaxxers, opponents to vaccines believe that a child's immune systems can deal with most infections naturally, and that injecting questionable vaccine ingredients into a child may cause side effects, including seizures, paralysis, and death, and may trigger autism and ADHD. CDC maintains that recommended vaccines, including the MMR and those that prevent diphtheria, smallpox, polio, and whooping cough, are both safe and effective.

Measles 2014

Today, CDC links nearly all of the measles cases this year to international travel by unvaccinated people. “Many of the clusters in the U.S. began following travel to the Philippines where a large outbreak has been occurring since October 2013,” Schuchat said. Of the 288 cases, 280 (or 97 percent) were associated with importations from at least 18 countries. More than one in seven cases has led to hospitalization, while a full 90 percent of all cases were in people who were not vaccinated or whose vaccination status was unknown.

However, people opposed to vaccinations are not the only problem. “Many U.S. health care providers have never seen or treated a patient with measles because of the nation’s robust vaccination efforts and our rapid response to outbreaks,” Schuchat said. CDC recommends health care providers who suspect a patient has measles collect specimens and then immediately isolate the patient before reporting to the local health department.

An average of 549,000 measles cases and 495 measles deaths were reported annually in the decade before the first live measles vaccine was licensed in 1963 for the U.S. The CDC believes it is much more likely that three to four million people were infected annually at that time, since most cases went unreported. Following the declared elimination of measles in the U.S., from 37 to 220 cases were reported annually between 2000- 2013, with the majority of cases occurring among unvaccinated people. (Elimination is defined as the absence for longer than a year of endemic transmission — when people get sick after coming into contact with someone indigenous to the area and not from someone in another country or infected travelers or immigrants.)