Mumps

Background

Mumps is a disease resulting from infection by the mumps virus. The disease is characterised by swelling of one or both cheeks or sides of the jaw, also known as parotitis, along with:

  • fever
  • headache
  • swollen glands

Mumps infection can also lead to serious complications including:

  • aseptic meningitis
  • encephalitis
  • inflammation of the testes
  • pancreatitis
  • oophoritis
  • permanent deafness

The most effective strategy for preventing the transmission of mumps is vaccination with the measles mumps rubella (MMR) vaccine.

More information on mumps can be found on the NHS inform website.

Guidance

Guidance on mumps: risk in pregnancy, infection in healthcare settings and the MMR vaccine can be found on the Public Health England website.

For all infection prevention and control guidance visit the A-Z ​pathogens section of the National Infection and Prevention Control Manual.

Data and surveillance

Surveillance update for April to June 2019

Mumps was a common childhood disease before the introduction of the MMR vaccine with more than 85% of adults having evidence of previous mumps infection. Following the introduction of the MMR vaccine in 1988, the incidence of mumps substantially decreased. However, since 2004 there has been ongoing widespread increased incidence of mumps throughout the UK with the number of laboratory confirmed cases peaking in 2005. As shown in Figure 1, smaller outbreaks have occurred in 2009, 2012 and 2014 to 2015. Most of the individuals affected were adolescents and young adults and had not had an opportunity to receive two doses of MMR – they had received one or none at all.

Figure 1 is a line chart showing the number of laboratory reports of mumps by year from 2000 to 30 June 2019. The figure shows the outbreak which occurred in 2004 and peaked in 2005 with 1887 and 2586 cases, respectively. While the number of cases has decreased since 2005, smaller outbreaks have occurred in 2009, 2012, 2015 and 2017. 424 cases were reported between 1 January and 30 June 2019.

Figure 2 shows that in the last four years, the number of laboratory confirmed mumps cases each year has been variable, ranging from 216 cases in 2016 to 817 in 2015. In late 2014 to 2015 a widespread outbreak occurred which mainly affected those in higher education with many cases having evidence of receiving two doses of MMR vaccine, due to the lower efficacy of the mumps component, compared with measles and rubella.

The observed increase in cases during this period may represent poor initial immune response to the mumps component of the MMR vaccine, waning immunity or a combination of both within fully and partially vaccinated individuals.

Figure 2 is a bar chart showing the number of laboratory reports of mumps by month from 2014 to 30 June 2019. The graph shows there was an increase in cases throughout 2015. An increase in cases was observed at the end of 2017 and continued into early 2018 but the number of cases decreased in the autumn and winter. The number of cases increased in the first two quarters of 2019.

In 2018, there were 280 laboratory confirmed mumps cases, a decrease compared to 2017 in which there were 385 cases reported. From 1 January to 30 June 2019, 424 laboratory confirmed mumps cases were reported. Mumps activity increased during quarter two to levels similar to previous years in which outbreaks were ongoing. A number of NHS boards experienced clusters of mumps cases up to June 2019, mainly in adolescents and young adults.

Age distribution of cases

Figure 3 shows that the majority of mumps cases in the past four years have been in those aged between 17 to 34 years, consistent with the age groups which are likely to be under immunised with a mumps containing vaccine.

Figure 3 presents the age breakdown of the laboratory reports for mumps by year from 2014 to 30 June 2019. The graph shows that every year the majority of mumps cases are in adolescents and young adults aged between 17 and 34 years.

From January to June 2019 in Figure 4, the incidence of mumps was highest in those in the 17 to 20 year-old age group at 64 cases per 100,000, followed by the 21 to 24 year old age group (45 cases per 100,000) and the 25 to 34 age group (10 cases per 100,000).

Figure 4 presents the number of laboratory reports of mumps by age group between 1 January and 30 June as a bar chart and the incidence rate per 100,000 as dots.  Figure 4 shows that incidence per 100,000 is highest in those aged 17 to 20 years at 64 cases per 100,000.

Laboratory confirmed cases by NHS boards

Figure 5 shows that the incidence of mumps varied greatly between NHS boards up to the end of second quarter of 2019 with the highest incidence in NHS Orkney (41 cases per 100,000) followed by NHS Borders (16 cases per 100,000) and NHS Greater Glasgow and Clyde (15 cases per 100,000). Note that due to the small population of NHS Orkney, even small increases in cases can lead to large fluctuations in incidence.

Figure 5 presents the number of laboratory reports of mumps by NHS board between 1 January and 30 June 2019 as a bar chart and the incidence rate per 100,000 as dots. There is variation between NHS boards with the highest rate in NHS Orkney at 41 cases per 100,000.

Limitations

There are limitations caused by a reliance on laboratory reports as this will represent a considerable underestimate of community circulation of mumps as many cases may be undiagnosed or based on clinical confirmation only.  It should also be noted that differences in sampling and testing practices may account for variation across the NHS boards.

Vaccination

Vaccine uptake statistics are available on the Information Services Division (ISD) website.