An Outbreak of Mumps Associated with a Bar and Grill - New Jersey, 2013

BACKGROUND:   Mumps is an acute viral infection characterized by parotitis; complications include orchitis, oophoritis, hearing loss, and meningitis.  Although the incidence of mumps has decreased since the introduction of routine mumps vaccination in the United States, outbreaks of mumps continue to occur in highly vaccinated populations.  During August through November 2013, New Jersey experienced an outbreak of mumps associated with a popular bar and grill in Belmar, a NJ shore community.

METHODS:   Surveillance for and investigation of mumps cases was conducted in conjunction with the county and local health departments.  An outbreak-associated case was defined as an individual with onset on or after July 15, 2013 who, during the incubation period, 1) lived in or visited Belmar, NJ or 2) had an epidemiologic link to an outbreak-associated case. Confirmed cases included symptomatic persons with laboratory confirmation of virus with reverse transcription polymerase chain reaction (RT-PCR) or culture in a patient with an acute illness consistent with mumps. Probable cases included persons with 1) acute parotitis or other salivary gland swelling lasting at least 2 days, or orchitis or oophoritis unexplained by another diagnosis and: a positive test for serum anti-mumps immunoglobulin M (IgM) antibody, OR epidemiologic linkage to another probable or confirmed case; or 2) a positive RT-PCR or culture with no clinical symptoms. 

RESULTS:   Immediate control measures were instituted including reviewing immunization records for exposed individuals, and administering measles-mumps-rubella vaccine to 37 potentially exposed individuals who were unvaccinated or unable to obtain proof of vaccination. The outbreak was declared over on December 6, 2013, with 8 confirmed and 45 probable NJ outbreak-associated cases.  Symptom onset dates ranged from August 3, 2013 through October 12, 2013. The median age was 27 years (range: 16 – 50).  Fifteen cases had documentation of receipt of two mumps-containing vaccines; two cases had documentation of one mumps-containing vaccine. One had serologic evidence of immunity. Eighteen cases reported receipt of two mumps-containing vaccines and one reported receipt of one mumps-containing vaccine, but have not provided documentation. Two cases reported being unvaccinated. Eight additional outbreak-associated cases (four confirmed and four probable) were identified in other states.   No index case was identified. 

CONCLUSIONS:   Mumps outbreaks continue to be identified in highly vaccinated populations.  Enhanced surveillance, education, and control measures, including isolation of ill persons, should be implemented to prevent similar outbreaks in the future.