An outbreak of mumps among young adults in Vancouver, British Columbia, associated with 'Rave' parties

In early 1997 an unexpectedly high number of cases of mumps was reported in Vancouver, British Columbia. Methods: A case control stud was conducted to address four objectives: 1) Describe the outbreak and the population at ri sk. 2) examine the impact of mumps on this population. 3) identify personal risk factors for infection, and 4) test the hypothesis that social gatheri ngs, 'rave parties in particular, were a risk factor in this outbreak. Resu lts: Mumps infection was associated with: attending a rave party [OR = 17; 95% CI: 2.7-710], residing in Vancouver [OR = 3.7; 95% CI: 1.4-10], and con tact with a person with mumps [OR = 13; 95% CI: 2-552], during the 'exposur e' period Vaccine effectiveness, ascertained by self-reported immunization status, was 80% [95% CI: 29%-96%]. Conclusions: Attendance at rave parties was associated with mumps infection during this outbreak. many persons aged 17-40 may remain susceptible to mumps; in BC these persons are eligible fo r one dose of MMR and should be encouraged to be vaccinated.