Mumps in Iowa
Cases of mumps in Iowa have been of concern lately, since it appears that state may have a possible outbreak. Researchers are still investigating actual vaccine coverage on college campuses, potential modes of transmission, and the effectiveness of one or two doses of MMR vaccine. Evidence suggests that these Iowa cases of mumps may be related to an outbreak in the United Kingdom.
In the United States, since 2001, an average of 265 mumps cases (the numbers range from 231 to 293) have been reported each year. In Iowa, an average of five mumps cases have been reported annually since 1996. However, by March 28, 2006, a total of 219 mumps cases had been reported in Iowa, and an additional 14 people with clinically compatible symptoms of mumps were being investigated in three neighboring states (11 in Illinois, 2 in Nebraska, and 1 in Minnesota) in what has become the largest epidemic of mumps in the United States since 1988.
In 1977, Iowa law mandated one dose of measles, mumps, and rubella (MMR) vaccine for entry to public schools; in 1991, the mandate became two doses. For the 2004-2005 school year, 97 percent of children entering school in Iowa had received two doses of MMR vaccine.
The first reports to the Iowa Department of Public Health (IDPH) of mumps-like illness occurred in December 2005 at a university in eastern Iowa, where several students with glandular swelling were tested; two tested positive for mumps-specific IgM antibodies.
In mid-January 2006, an isolate from an unrelated patient was cultured and identified as mumps virus at the University Hygienic Laboratory (Iowa's state public health laboratory). Viral isolates were sent to the Centers for Disease Control and Prevention (CDC), and the mumps virus strain was identified as genotype G. By mid-February, active surveillance had been initiated in seven geographic areas, including the campuses of the three largest universities in Iowa.