Measles is on the rise this year, raising concern among U.S. health authorities. According to the Centers for Disease Control and Prevention (CDC), 288 cases of measles were reported between January 1 and May 23, 2014 in this country. This is the largest number of measles cases in the U.S. reported in the first five months of a year since 1994.
Measles is a highly contagious viral infection that is transmitted through respiratory secretions. The virus infects cells in the lungs and at the back of the throat, causing symptoms such as fever, cough, pink eye, runny nose, white spots in the mouth, and a rash that typically starts on the face and spreads down the body to the trunk and legs. The symptoms usually appear 7 to 14 days after someone is infected, and most people recover within a couple weeks. However, 30% develop complications such as pneumonia, ear infections, and diarrhea, and it can be especially serious for children, pregnant women, and those who are immunocompromised or malnourished.
Public health officials have worked hard to try to eradicate measles in the United States since a vaccine was first licensed in 1963, and in 2000, endemic measles was declared eliminated from the U.S. However, from 2001 through 2011, 63 outbreaks of measles were reported, albeit small ones. According to the CDC, these cases occurred among people who were exposed to "imported" measles from other countries where the disease remains endemic and who were unvaccinated. High overall population immunity and the high effectiveness of the measles vaccine kept the number of cases in those outbreaks in check.
In the case of this year's measles increase, the CDC says that nearly all of the cases reported (97%) have been linked to international travel by U.S. residents or visitors who had not been vaccinated against the disease. The CDC is especially concerned because more than one in seven cases in 2014 has resulted in those affected being hospitalized.
"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 [it] 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, in a press release. "Many of the clusters in the U.S. began following travel to the Philippines where a large outbreak has been occurring since October 2013."
The CDC recommends that healthcare professionals use all patient encounters to make sure that people are up to date on all vaccinations, especially before international travel. It also advices that patients who have a fever and rash as well as a cough, runny nose, or pink eye be evaluated for measles, especially if the person has not been vaccinated against measles and either recently traveled internationally or was exposed to someone who did or who has measles.
Laboratory confirmation of measles is critical for all sporadic cases of the disease and all outbreaks for public health disease surveillance purposes. The most common testing methods to confirm measles involve taking a blood sample to look for measles-specific IgM antibodies and a throat or nasopharyngeal swab to look for measles RNA through polymerase chain reaction (PCR) testing. Urine samples may also contain measles virus and should be collected if feasible in order to improve the chance of detecting the measles virus quickly.
Vaccination is the best way to prevent measles. The CDC recommends two doses of measles, mumps, and rubella (MMR) vaccine for everyone, starting at age 12 months. In the case of international travel, it recommends that those who are not immune to measles receive two doses of the MMR vaccine, both for their own protection and to prevent importation of the measles virus into the U.S. Specifically, before any international travel, the CDC recommends that infants 6 months through 11 months of age should have at least one dose of MMR vaccine and children 12 months or older should have two doses at least 28 days apart. Adults should review their vaccination records to confirm that they are current.
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Centers for Disease Control and Prevention. Press Release: Measles cases in the United States reach 20-year high. Available online at http://www.cdc.gov/media/releases/2014/p0529-measles.html through http://www.cdc.gov. Accessed June 10, 2014.
Centers for Disease Control and Prevention. Manual for the Surveillance of Vaccine-Preventable Diseases. Chapter 7: Measles. Available online at http://www.cdc.gov/vaccines/pubs/surv-manual/chpt07-measles.html through http://www.cdc.gov. Accessed June 10, 2014.
Centers for Disease Control and Prevention. Measles (Rubeola). Signs and Symptoms. Available online at http://www.cdc.gov/measles/about/signs-symptoms.html through http://www.cdc.gov. Accessed June 10, 2014.
Centers for Disease Control and Prevention. Measles (Rubeola). Complications of Measles. Available online at http://www.cdc.gov/measles/about/complications.html through http://www.cdc.gov. Accessed June 10, 2014.
Centers for Disease Control and Prevention. Vaccines and Immunizations. Measles - Recommendations for Prevention. Available online at http://www.cdc.gov/vaccines/vpd-vac/measles/dis-detail-rec.htm#traveler through http://www.cdc.gov. Accessed July 2, 2014.