Through vaccination and control efforts, the burden of mumps disease has been severely reduced in the United States. Recent resurgence in 2016 has resulted in outbreaks of disease, with both the United States and Texas experiencing the highest incidence of mumps in ten and twenty-two years respectively. In November 2016, the Texas Department of State Health Services, Health Service Region 2/3 was notified of three mumps cases in residents of two adjacent North Texas cities within Johnson County. An outbreak investigation was initiated and additional cases of mumps were identified.
METHODS:
Investigation into cases included retrospective and current case finding. Mumps cases were classified according to CSTE case definition. Three vaccination clinics were held in both school and faith-based settings and individuals in exposure settings with no or unknown vaccination history were offered MMR vaccine. Serology, polymerase chain reaction, and genotyping were performed.
RESULTS:
As of March 31, 2017, 186 confirmed and probable cases have been identified in this outbreak with earliest onset of disease in November,2016. Investigation revealed one initial case traveled during the incubation period to another state experiencing a mumps outbreak. Health advisories lead to enhanced awareness and the identification of additional cases. A plurality of case-patients are Asian/Pacific Islander (48%) and most are 5-18 years of age (60%). A large proportion (64%) of cases are either students or staff at two school districts within the county, resulting in the recommendation to exclude individuals not vaccinated per state mandated vaccination schedules in the exposure settings. In cases with verified vaccination history, a vast majority (92%) had received one or more doses of the MMR vaccine. Notification of healthcare providers of possible exposure to mumps cases identified seven healthcare workers who had unprotected exposures at a healthcare facility and exclusion from duties was recommended. Unprotected exposure resulted in transmission of mumps to one healthcare worker. The outbreak in Johnson County is still ongoing.
CONCLUSIONS:
The outbreak in Johnson County is the largest mumps outbreak in Texas in over twenty years, with over 180 cases. A variety of settings in the community were affected including schools, healthcare facilities, churches, local businesses, and missionary groups. Districtwide school exclusion of unvaccinated and under vaccinated contacts revealed a gap in school response planning to prolonged public health exclusion recommendations. In-person community outreach as well as coordinated contact with faith-based community advocates allowed for reaching targeted, high risk groups during the outbreak.