As of May 20, 118 cases of measles in people aged 3 months to 68 years had been reported in the United States this year, the highest number reported for this 19-week period in any year since 1996, according to the Centers for Disease Control and Prevention.
Most of the cases (105 or 89%) were associated with importation from other countries, an “unusually large number of importations” that was related to recent increases in measles in countries visited by U.S. travelers, according to the Morbidity and Mortality Weekly Report (2011;60:[Early Release]1–4). Most of the cases that were associated with importations from European countries were from France, where about 10,000 cases of measles have been reported from January through April this year. Between 2001 and 2008, the CDC received a median of 56 reports of measles annually.
Fifty-three (45%) of the cases were in people aged 20 years and older; of the rest, 18 (15%) were in children under age 12 months, 24 (20%) were children aged 1–4 years, and 23 (19%) were in individuals aged 5–19 years.
Of the 118 reported cases from 23 states and New York City, 105 (89%) had not been vaccinated. The cases included 45 U.S. residents aged 1–19 years, of whom 39 (87%) had not been vaccinated: In 24 cases, parents had claimed religious or personal exemption and 8 had missed opportunities to be vaccinated.
Of the 42 U.S. residents aged 20 and older who were among the cases, 35 (83%) had not been vaccinated, including 6 who declined vaccination because of “philosophical objections to vaccination.” Of the 33 U.S residents who were eligible to receive the vaccine and had traveled abroad, 30 (91%) were not vaccinated, and in one case (3%), the person had received one of the two recommended doses.
The size of the outbreaks ranged from 3 to 21 cases. The 21 cases were in a community in Minnesota where many children were not vaccinated because parents were concerned about the safety of the measles, mumps, and rubella (MMR) vaccine. That outbreak resulted in infection of at least seven infants who were too young to receive the MMR vaccine.
Nine outbreaks accounted for 58 (49%) of the 118 cases and, in 6 outbreaks, the index case acquired measles abroad; the source of the other 3 outbreaks could not be determined.
Of the 118 cases reported between Jan. 1, 2011, and May 20, 2011, there were no deaths or cases of encephalitis, but 40% (47) needed to be hospitalized, and there were nine cases of pneumonia.
Because cases of measles continue to be imported into the United States, clinicians should suspect measles in people with a febrile rash illness and “clinically compatible symptoms,” such as cough, coryza, and/or conjunctivitis, “who have recently traveled abroad or have had contact with travelers.” This is particularly true if the patient is unimmunized either by choice, by young age or a true contraindication to the vaccine. When measles is suspected, clinicians should use airborne isolation in a medical facility or home quarantine of the patient, along with known conatacts during the incubation period. Also, report the case immediately to the local health department, and obtain viral specimens for testing, according to the report.