Mumps in Ireland, 2004-2008.

Following a national mumps outbreak that began in November 2004 and continued into 2005, the number of mumps notifications in Ireland waned in the latter half of 2006 and during 2007 (Figure 1). However, mumps notifications have started to increase again in 2008 (Figure 1). The number of mumps notifications annually between 1988 and 2008 and the number of confirmed mumps notifications by year from 2004 to 2008 are shown in Figure 2. The highest number of notifications and the highest incidence rates, from the start of the outbreak in Week 44 of 2004 to Week 16 of 2008, were in the age groups 15-19 years and 20-24 years (Figures 3 and 4). The setting in which the cases had most likely acquired mumps was reported for 25 percent of the notifications (n=535/2156) since the start of the outbreak; for the majority of these, college/university (48 percent) or secondary school (12 percent) were reported as the locations the infection was most likely to have been acquired. Vaccination status was only reported for 35 percent (n=753/2156) of notifications since November 2004. Where vaccination status was reported, 35 percent of the cases were unvaccinated, 36 percent had received one dose of the combined measles-mumps-rubella vaccine (MMR), 28 percent had received two doses and one percent had received at least one dose (but it was unclear if they had also received a second dose). Reported vaccination status was obtained through a number of sources, such as local immunisation databases, general practitioner's records and case/parental records or recall. Due to recall bias by cases/parents, there may therefore be some inaccuracies in the vaccination status figures reported above. Eighty-four cases were hospitalised, representing 10 percent (n=84/855) of all cases with known hospitalisation status. Reported complications of mumps include orchitis (19 percent, n=86/442), deafness (1.6 percent, n=11/707), meningitis (1.5 percent, n=11/718), pancreatitis (1 percent, n=6/629), mastitis (0.6 percent, n=4/644) and encephalitis (0.3 percent, n=2/714). Notification data 2008 In contrast to the 153 mumps notifications for Weeks 1-16 2008, there were 34 mumps notifications during the same period in 2007 and 150 mumps notifications for the whole of 2007 (Figures 1 and 2). To date in 2008, 87 of the 153 notifications are classified as laboratory-confirmed, nine as probable, 43 as possible, while 14 have no case classification specified. The highest number of notifications in 2008 are in the age groups 15-19 years (n=34), 20-24 years (n=26) …