Mumps outbreak as 2,000 cases reported

There has been a major outbreak of mumps in Ireland over the past 12 months with almost 2,000 cases of the highly infectious disease having been notified to the health authorities.

A significant number of the outbreaks were in the HSE South region which includes Cork, Kerry, Waterford and South Tipperary and where notifiable cases were twice the national average. However, the highest incidence of mumps was in the North-West.

The scale of the outbreak, since July 2014, has led the Health Protection Surveillance Centre to recommend an increase in the overall coverage of the MMR vaccine among teenagers and young adults to prevent similar large outbreaks in future.

The centre said official figures showed there were large gaps in the uptake of the two-dose MMR vaccination. It claimed many outbreaks were linked to schools, colleges and universities as well as among families.

The centre, which monitors all infectious disease in the Republic, also observed the vaccination status of patients was not routinely available or reported. Such data was not available in 41% of all cases.

Nevertheless, the centre said it appeared a large proportion of cases had received one to three doses of the MMR vaccine with a majority having had at least one vaccine. The vaccine, introduced in Ireland in 1988, protects against measles, mumps and rubella. It is usually given to children aged 12 months followed by a booster dose at 4 to 5 years.

The infection can be highly dangerous in older children and adults as it can lead to serious complications such as meningitis and encephalitis through secondary infection.

As there is no cure for mumps, treatment is aimed at relieving the symptoms and preventing the further spread of infection.

The HPSC said recent results were in line with other international outbreaks of mumps which had shown waning immunity to the mumps component of the MMR vaccine as a factor in a number of outbreaks of the disease.

Research has shown there were 1,993 reported cases of mumps notified to the health authorities in the past 12-month period with outbreaks reported across most regions and all age groups. Males accounted for 56% of all cases.

The median age of those infected was 20 years, although the youngest sufferer was two-months-old while the eldest was aged 89 years.

Two-thirds of those infected with mumps were aged 15 to 24. Among those cases for whom vaccination data was available in the 15 to 24 age group, a large majority of these reported having received two doses of the MMR vaccine.

Patients in the HSE South region, which also includes Carlow and Kilkenny, accounted for 29% of all cases with a notification rate twice the national average at 86.7 per 100,000 population.

However, the highest incidence of mumps was in the North-West (with 93.3 cases per 100,000), while the national average was 43.4 per 100,000 population. The lowest rate (17 per 100,000) was seen in the North-East.

Only 48% aged 12 months or older of those infected were reported as having one or more vaccinations, while the vaccination status of more than 1,000 cases was unknown or not reported.

Two doses of the MMR vaccine are 88% effective at preventing mumps while one dose provides 78% cover.