Mumps Virus Detection During an Outbreak in a Highly Unvaccinated Population in British Columbia

Objectives: Control measures of mumps involve isolation of those symptomatic or potentially exposed. Recent guidelines have recommended shortening the isolation period from 9 days to 5 days after the onset of parotitis, despite using mainly historical evidence. In British Columbia, mumps circulated in a predominantly unvaccinated population in 2008. We compared laboratory findings between the different vaccination groups and assessed the period of mumps viral detection after onset of parotitis. Methods: Demographic and clinical data were collected according to guidelines during the course of the outbreak. Clinical specimens, including buccal swabs, urine, CSF and sera, were collected on a single visit upon presentation for diagnosis. Laboratory diagnosis of mumps was confirmed by either virus detection by PCR and/or isolation in cell culture from clinical specimens, or by serology. Results: Laboratory testing confirmed mumps on 85 (74%) of 115 cases by virus detection and/or serology. Thirty-nine (78%) of 50 cases had virus detected within the first 5 days after onset of parotitis, with the rate highest in specimens collected early. However, virus could be detected in 5 (56%) of 9 cases after day 5 and up to day 9. Conclusion: Our study questions whether a 5-day isolation period is sufficient to prevent mumps transmission in a susceptible population. Our observations are based on single specimen submission, whereas an optimal study design would entail serial collection after presentation of parotitis, as this reflects true viral shedding. Further investigations are warranted to validate patient isolation guidelines. Objectifs : La lutte contre les oreillons consiste à isoler les personnes symptomatiques ou potentiellement exposées. Des lignes directrices récentes recommandent de réduire la période d'isolement de 9 à 5 jours après l'apparition d'une parotidite, mais les preuves à l'appui sont principalement de nature historique. En Colombie-Britannique, les oreillons ont circulé en 2008 dans une population majoritairement non vaccinée. Nous avons comparé les résultats de laboratoire des deux groupes (vaccinés et non vaccinés) et déterminé le délai de détection virale des oreillons après l'apparition de la parotidite. Méthode : Nos données démographiques et cliniques ont été recueillies selon les lignes directrices, durant l'éclosion. Des prélèvements cliniques (buccaux, urinaires, de liquide céphalorachidien et de sérum) ont été obtenus au cours d'une même