Mumps is a viral illness spread by respiratory droplets and characterized by parotitis or inflammation of other salivary glands. An outbreak of mumps occurred in the Rockaways area of Queens in New York City (NYC) from June through November, 2015.
METHODS:
Mumps cases were reported to NYC Department of Health and Mental Hygiene (DOHMH) by health care providers and laboratories reporting positive mumps test results from August 16 through November 2, 2015. DOHMH conducted active surveillance to identify retrospective cases with onsets before August 14, 2015. DOHMH interviewed reported cases and reviewed medical records. Suspect cases were classified according to Council of State and Territorial Epidemiologists criteria. Diagnostic testing included immunoglobulin M (IgM) in serum and polymerase chain reaction (PCR) of buccal swabs.
RESULTS:
DOHMH identified 52 cases associated with the outbreak. Through retrospective case finding, DOHMH identified 6 cases with dates of onset as early as 2 months before the before the onset date of the first passively reported case. Providers did not report these 6 cases to DOHMH, because serologic IgM testing had been negative or the provider did not suspect mumps. Median age of cases was 31 years; all but 2 were adults over 18 years. No cases were hospitalized or had complications. Of the 50 cases with laboratory testing, 32 (64%) were positive by any test, 29 (66%) of 44 tested by PCR were positive, and 7 (15%) of 47 tested for IgM were positive. Twenty-two cases reported attending several neighborhood bars and restaurants in common. Control measures included home isolation of potentially infectious cases, notifications to Rockaways providers, provision of no cost vaccines to 2 local clinics, and the distribution of informational posters and flyers in the affected neighborhoods. A DOHMH Facebook ad campaign targeted to users aged 20 through 59 years in the Rockaways zip codes was shown to 86,118 unique individuals during its run from October 30 through November 17, 2015.
CONCLUSIONS:
Delayed recognition of this outbreak highlights the importance of PCR testing, reporting all suspected cases of mumps to DOHMH, and recognition that negative laboratory results or evidence of immunity do not exclude mumps. Social media was a valuable tool for successfully and rapidly reaching a large population in the target demographic during the outbreak.