During 2006, 180 cases of mumps (3.7 per 100,000) were reported to MDH. By comparison, one to six cases had been reported annually in each of the previous 5 years. A total of 22 cases were reported in Minnesota between 2001 and 2005.
A multi-state resurgence of mumps occurred in the United States in 2006. Eight Midwestern states including Minnesota, Iowa, Kansas, Illinois, Missouri, Nebraska, South Dakota, and Wisconsin reported mumps incidence rates of more than 2 per 100,000. Forty-five states and Washington D.C. reported a collective total of 6,330 mumps cases, the largest outbreak in more than 20 years. The first outbreak cases occurred in college students in eastern Iowa in December 2005; peak incidence occurred in April 2006 in Iowa and other outbreak states, including Minnesota.
In Minnesota, case-patients ranged in age from 2 months to 92 years. The highest age-specific attack rate occurred in persons 18-24 years of age (42 [23%] cases; 7.9 per 100,000). This is consistent with other outbreak states for which the overall age-specific attack rate for persons 18-24 years of age was 6.0 per 100,000, affecting primarily college students. Sixty-seven (37%) cases occurred in children <18 years of age (5.2 per 100,000); 40 (22%) occurred in adults 25-49 years of age (2.1 per 100,000); and 31 (17%) occurred in adults age >50 years of age (2.1 per 100,000). The comparable age-specific incidence rates in adults 25-49 years of age and those aged >50 years do not support the assumption that persons born before 1957 are immune to mumps due to natural infection.
IgM and IgG serologic testing, and viral culture, should all be performed on suspect mumps cases. False-positive indirect immunofluorescent antibody (IFA) results for mumps IgM antibody have been reported, particularly in persons who are infected with Epstein Barr Virus (EBV). Initial specimens for IgM and acute IgG should be drawn 4-7 days after onset of symptoms. In previously vaccinated persons, the expected rise in IgM antibody may be delayed or absent; therefore, healthcare providers should consider repeating initially negative IgM serologic tests at least 1 week after onset in previously vaccinated persons. Mumps is confirmed by viral culture of buccal swabs, throat swabs, urine, or spinal fluid specimens. Specimens for viral culture should be collected as soon as possible during the first 5 days of illness.
- Note: For up to date information see: Mumps
- Go to full issue: Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2006