Investigation of a Mumps Outbreak at a Large University in Columbus, OH, January–July 2014

BACKGROUND:  Columbus Public Health investigated a mumps outbreak associated with a large university in Columbus, OH, during January–July 2014.  Objectives of this investigation were to determine the extent of the outbreak, describe case and outbreak characteristics, identify sub-clusters, and implement appropriate interventions. 

METHODS:  A confirmed mumps case was defined as clinically compatible illness (acute parotitis or other salivary gland swelling lasting ≥2 days, aseptic meningitis, encephalitis, hearing loss, orchitis, oophoritis, mastitis, or pancreatitis) with laboratory confirmation by reverse transcription polymerase chain reaction (RT-PCR) or culture.  A probable mumps case was defined as acute parotitis or other salivary gland swelling lasting ≥2 days or orchitis or oophoritis without other apparent cause, and a positive IgM antibody test, epidemiologic link to a mumps case, or epidemiologic link to the outbreak setting or community.  Confirmed and probable mumps cases occurring on or after January 1, 2014, and with an epidemiologic link to the university were included in this investigation.  A sub-cluster was defined as ≥2 mumps cases linked to a specific residence hall, fraternity, sorority, academic major, or athletic team. Case information was obtained through interviews, reports to public health, and record reviews.  Local public health collaborated with university officials, healthcare providers, the Ohio Department of Health, and the Centers for Disease Control and Prevention to implement control measures.

RESULTS:  A total of 254 university-linked mumps cases occurred during January 28–July 7, 2014.  Of these cases, 163 (64%) were university students, 57 (22%) were community members, and 34 (13%) were university employees. Cases ranged in age from 11 months to 75 years (mean = 27 years; median = 21 years); 154 cases (61%) were female.  Of cases with known vaccination status, 212 (95%) reported receiving ≥1 dose of mumps vaccine, and 178 (80%) reported ≥2 doses.  Sixty sub-clusters were identified:  12 within fraternities or sororities, 6 within residence halls, 39 within academic majors, and 3 within athletic teams.  Fraternity or sorority membership was reported by 45% of student cases, compared to 11% of the general student body.  Public health interventions included isolation of cases, enhanced surveillance, health education, promotion of vaccination, and provision of guidance to healthcare providers.

CONCLUSIONS:  This mumps outbreak occurred among a highly vaccinated population of students, employees, and other contacts of a large university, with substantial transmission among fraternities and sororities.  Collaboration between public health, university officials, and healthcare providers was critical to outbreak investigation.