Indiana Epidemiology Newsletter
Wayne Staggs, MS
ISDH Invasive Disease Epidemiologist
Kristin Ryker, MPH
ISDH Vaccine-Preventable Disease Epidemiologist
On May 1, 2008, the Centers for Disease Control and Prevention (CDC) issued a Morbidity and Mortality Weekly Report (MMWR) dispatch reporting increased incidence of measles in the United States during the first four months of 2008. The CDC received 64 reports of confirmed measles cases from January 1-April 25, 2008. This is the highest number of reported cases for the same period of time since 2001.
The dispatch reported on cases in nine different states, three of which border on or are near Indiana. One of the cases was contagious while in Chicago, with rash onset around April 17. The proximity of the case to Indiana and the public venues the case visited in Chicago concerned investigators at the Indiana State Department of Health (ISDH) and local public health officials. As of May 16, no secondary cases have been reported from exposure to this case. At the time of dispatch publication, ongoing outbreaks were occurring in Wisconsin, Arizona, Michigan, and New York. Since the dispatch was issued, additional cases of measles have been reported in the state of Washington and Toronto, Canada.
Of the 64 reported cases in the dispatch, 59 occurred among U.S. residents, and 54 were associated with importation of measles from other countries. Sixty-three of the 64 cases were unvaccinated or had unknown vaccine history. The May 1 dispatch can be read in its entirety at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5718a5.htm.
The recent cases and outbreaks resulted primarily from imported cases who then exposed groups of individuals who were unvaccinated due to personal or religious beliefs. Transmission occurred primarily in community and health care settings, including homes, child-care centers, schools, hospitals, emergency departments, and the offices of health care providers. These cases strongly illustrate:
In 2005, Indiana reported the largest measles outbreak (34 cases) in the U.S since 1996. All cases in this outbreak were a result of importation into a population with low vaccination rates. Twenty-seven cases occurred in those aged 1-19 years, 26 of whom were unvaccinated. This recent Indiana outbreak is a stark reminder that measles outbreaks can occur anywhere there are groups or clusters of persons with low vaccination coverage.
This outbreak is described in the MMWR, October 28, 2005, Volume 54, No. 42, found at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5442a1.htm or in the September 2005 issue of the Indiana Epidemiology Newsletter at http://www.in.gov/isdh/dataandstats/epidem/2005/sept/Sept05newsletter.pdf
Measles is characterized by fever (≥101° F.), cough, coryza, and conjunctivitis followed by a generalized rash 2-4 days later. The rash begins on the face and then spreads to the rest of the body and is present for three or more days. Persons suspected of having measles should be questioned about travel to any area of the country affected by measles or international travel to determine risk exposure. Health care providers who identify possible cases are asked to report the case immediately to the local health department or to Kristin Ryker, ISDH Vaccine-Preventable Disease Epidemiologist, at 317.233.7125. Unvaccinated persons meeting the clinical case definition* who have traveled outside of the U.S. or to areas with ongoing measles transmission should be treated as highly suspect.
Although ongoing measles transmission was declared eliminated in the U.S. in 2000, the risk for imported disease and outbreaks remains. The cases reported in the May 1, 2008, MMWR dispatch and the recent Indiana outbreak highlight the risk created by importation of disease into groups of people with low vaccination rates.
For further information on the diagnosis of measles, including the preferred laboratory specimens needed to confirm the diagnosis, please visit the ISDH Web site at http://www.in.gov/isdh/pdfs/measles.pdf
*Measles Clinical Case Definition: an illness characterized by all of the following: