Viruses Detected Among Sporadic Cases of Parotitis, United States, 2009-2011

Background. Sporadic cases of parotitis are generally assumed to be mumps, which often requires a resourceintensive public health response. This project surveyed the frequency of viruses detected among such cases. Methods. During 2009–2011, 8 jurisdictions throughout the United States investigated sporadic cases of parotitis. Epidemiologic information, serum, and buccal and oropharyngeal swabs were collected. Polymerase chain reaction methods were used to detect a panel of viruses. Anti–mumps virus immunoglobulin M (IgM) antibodies were detected using a variety of methods. Results. Of 101 specimens, 38 were positive for a single virus: Epstein-Barr virus (23), human herpesvirus (HHV)-6B (10), human parainfluenza virus (HPIV)-2 (3), HPIV-3 (1), and human bocavirus (1). Mumps virus, enteroviruses (including human parechovirus), HHV-6A, HPIV-1, and adenoviruses were not detected. Early specimen collection did not improve viral detection rate. Mumps IgM was detected in 17% of available specimens. Patients in whom a virus was detected were younger, but no difference was seen by sex or vaccination profile. No seasonal patterns were identified. Conclusions. Considering the timing of specimen collection, serology results, patient vaccination status, and time of year may be helpful in assessing the likelihood that a sporadic case of parotitis without laboratory confirmation is mumps.