Mumps Outbreak — New Jersey, September–December 2009

Background: Mumps, a vaccine-preventable disease, is characterized by fever and inflammation of the salivary glands; complications include orchitis, oophoritis, deafness, and meningoencephalitis. In September 2009, we identified a mumps outbreak in NJ linked to a larger outbreak of >400 cases in NY and Canada and associated with a tradition-observant religious community. The index case for the larger outbreak was in a NY child who had traveled to the United Kingdom where genotype G mumps virus was circulating.

Objectives: We investigated the NJ outbreak to identify the source, characterize the outbreak, and develop control measures.

Methods: We defined a probable case as a clinically-compatible illness; a confirmed case had either laboratory-confirmation or an epidemiologic link to another confirmed or probable case. We interviewed patients and their physicians by telephone and collected laboratory information.

Results: As of December 3, a total of 80 confirmed and probable cases were reported among NJ residents; 76% were male (median: 18 years, range: 1–61 years). Complications were reported among 11 (13.8%) patients: orchitis (10) and oophoritis (1). No hospitalizations or deaths have been reported. Mumps vaccination status was known for 69 (86.3%) patients; receipt of two mumps vaccine doses included two (25.5%) of eight patients aged 1–6 years, 29 (90.6%) of 32 patients aged 7–18 years, and 16 (57.1%) of 28 patients aged 19–52 years.  Genotype G virus was isolated from tested patients.

Conclusions: Extensive and ongoing transmission of mumps has been identified in multiple locations in the United States and Canada and has resulted in the largest mumps outbreak in the United States since 2006. Enhanced surveillance, education, and control measures, including isolation of ill persons, should be implemented to prevent similar outbreaks.