US Measles Cases Reach 20-Year High; Largest Outbreak Since Elimination in 2000

Two hundred and eighty-eight cases of measles were reported to the CDC in the United States between Jan. 1 and May 23, 2014. This is the largest number of measles cases in the United States reported in the first five months of a year since 1994. Nearly all of the measles cases this year have been associated with international travel by unvaccinated people. Maintenance of high vaccination coverage, ensuring timely vaccination before travel, and early detection and isolation of cases, are key factors to limit importations and the spread of disease.


“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 and director of the CDC’s National Center for Immunizations and Respiratory Diseases. “Many of the clusters in the U.S. began following travel to the Philippines where a large outbreak has been occurring since October 2013.”


Of the 288 cases, 280 (97 percent) were associated with importations from at least 18 countries. More than one in seven cases has led to hospitalization. Fifteen outbreaks accounted for 79% of cases reported, including the largest outbreak reported in the United States since elimination (138 cases and ongoing).


Ninety percent of all measles cases in the United States were in people who were not vaccinated or whose vaccination status was unknown. Among the U.S. residents who were not vaccinated, 85 percent did not get vaccinated for religious, philosophical or personal reasons.


The large number of measles cases this year stresses the importance of vaccination. Healthcare providers should use every patient encounter to ensure that all of their patients are up to date on vaccinations, especially, before international travel. Infants and young children are at high risk of getting a serious case of measles. The CDC recommends two doses of measles, mumps, and rubella (MMR) vaccine for everyone starting at age 12 months. For those travelling internationally, the CDC recommends that all U.S. residents older than 6 months receive MMR vaccine, if needed, prior to departure.


More than ever, health care providers need to be alert to the possibility of measles and be familiar with the signs and symptoms so they can detect cases early. “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,” said Schuchat.


Patients who present with fever and rash along with cough, runny nose, or pink eye should be evaluated for measles, especially, if the patient is unvaccinated and recently traveled internationally or was exposed to someone else who has measles or recently traveled. Measles cases have been initially misdiagnosed as Kawasaki disease, dengue, and scarlet fever, among other diseases, underscoring the importance of considering measles in the differential diagnosis of clinically compatible cases.


Because patients with measles often seek medical care, early recognition of suspected measles cases and implementation of appropriate infection control measures are vital to reduce transmission in health-care settings. Where possible, because of the high transmissibility of measles, patients with suspected measles should be promptly screened before entering waiting rooms and appropriately isolated (i.e., in an airborne isolation room or, if not available, in a separate room with the door closed), or have their office appointments scheduled at the end of the day to prevent exposure of other patients. Healthcare providers should immediately report the case to their local health department and collect specimens for serology and viral testing.


Measles is a highly contagious, acute viral illness that can lead to serious complications and death. Anyone who is not protected against the disease is at risk, especially if they travel internationally. Measles is still common in many parts of the world, including countries in Europe, Asia, the Pacific, and Africa. Worldwide, an estimated 20 million people get measles and 122,000 die from the disease each year. Measles was eliminated from the United States in 2000, meaning that there was no longer continuous measles transmission for more than 12 months.


Patients with reported measles cases this year have ranged in age from 2 weeks to 65 years; 18 (6%) were under 12 months old, 48 (17%) were between one and four years old, 71 (25%) were aged between five and 19 years old, and 151 (52%) were 20 years old or older. Forty-three (15%) were hospitalized, and complications have included pneumonia (five patients), hepatitis (one), pancytopenia (one), and thrombocytopenia (one). No cases of encephalitis and no deaths have been reported.


Measles cases have been reported from 18 states and New York City. Most cases were reported from Ohio (138), California (60), and New York City (26). Fifteen outbreaks have accounted for 227 (79%) of the 288 cases. The median outbreak size has been five cases (range: 3–138 cases). There is an ongoing outbreak involving 138 cases, occurring primarily among unvaccinated Amish communities in Ohio.


Of the 288 cases, 280 (97%) were associated with importations from at least 18 countries. The source of measles acquisition could not be identified for eight (3%) cases. Forty-five direct importations (40 U.S. residents returning from abroad and five foreign visitors) have been reported. Almost half (22 [49%]) of these importations were travelers returning from the Philippines, where a large outbreak has been occurring since October 2013.


Most of the 288 measles cases reported this year have been in persons who were unvaccinated (200 [69%]) or who had an unknown vaccination status (58 [20%]); 30 (10%) were in persons who were vaccinated. Among the 195 U.S. residents who had measles and were unvaccinated, 165 (85%) declined vaccination because of religious, philosophical, or personal objections, 11 (6%) were missed opportunities for vaccination, and10 (5%) were too young to receive vaccination.


See the CDC Announcement


See the CDC Report


See also Medical Law Perspectives, January 2013 Report: Vaccines: An Ounce of Prevention May Lead to a Pound of Injury