Research and analysis

Laboratory confirmed cases of measles, rubella and mumps in England: January to March 2023

Updated 3 May 2024

Applies to England

Measles, rubella and mumps are notifiable diseases and healthcare professionals are legally required to inform their local health protection team (HPT) of all suspected cases. National enhanced surveillance including oral fluid (OF) testing of all suspected cases is provided through the Virus Reference Department (VRD) at Colindale to support and monitor progress towards World Health Organization (WHO) measles and rubella elimination targets.

Two WHO indicators are of prime importance for measuring the performance of national measles and rubella surveillance systems. These are:

1. The rate of laboratory investigations (at least 80% of suspected cases).
2. The annual rate of discarded cases (at least 2 per 100,000 population).

In order to achieve these targets, the focus of the UK Health Security Agency (UKHSA) is on ensuring that all suspected cases are appropriately tested. Immunoglobulin M (IgM) serology testing and oral fluid testing are the only tests considered adequate by WHO for confirming – and, importantly, discarding – suspected measles and rubella cases. Recent infection is confirmed by measuring the presence of IgM antibodies or detecting viral RNA (by PCR) in these samples.

Samples that have been confirmed positive for measles or rubella are further sequenced and entered on the WHO global Measles Nucleotide Surveillance (MeaNS) or the Rubella Nucleotide Surveillance (RubeNS) system, respectively, which are hosted at the National Reference Laboratory. Genotyping and further characterisation of measles and rubella is used to support investigation of transmission pathways and sources of infection.

Data presented here is for the first quarter of 2023 (January to March). Analyses are done by date of onset of rash or symptoms and regional breakdown figures relate to Government Office Regions.

Historical annual and quarterly measles, rubella and mumps epidemiological data is available from 2013 onwards:

• Measles: confirmed cases
• Mumps: confirmed cases
• Rubella: confirmed cases

Results from all samples tested at Colindale are reported on the MOLIS/LIMS system and reported back to the patient’s GP and local HPT.

Table 1. Total suspected cases of measles, rubella and mumps reported to HPTs: weeks 1 to 12 of 2023

Notified as	Number of suspected cases*	Number (%) tested by OF. [Target: 80% (measles and rubella only)]	Other samples received in Virus Reference Laboratory	Number of samples IgM positive or viral detection	Discard rate based on negative tests per 100,000 population (all samples)**
Measles	454	222 (49%)	57	31	0.44
Rubella	66	754 (38%)	109	0	0.07
Mumps	1,608	109 (47%)	15	51	–

*This represents all cases reported to HPTs in England, that is, possible, probable, confirmed and discarded cases on HPZone.

**The rate of suspected measles or rubella cases investigated and discarded as non-measles or non-rubella using laboratory testing in a proficient laboratory. The annual discard rate target set by WHO is 2 cases per 100,000 population. We present quarterly rates here with an equivalent target of 0.5 per 100,000 population.

Measles

In the period between January and March 2023, 31 laboratory confirmed cases of measles were reported in England compared to 7 cases reported in the previous quarter (Figure 1) (1). Of these 31 cases:

• 7 (23%) were imported and 3 (9.7%) were import-related
• 35% of the confirmed cases (11 out of 31) were in children under 5 years of age
• 38% (12 out of 31) were in 15 to 34-year-olds
• 13% (4 out of 31) were previously vaccinated, 2 were partially vaccinated
• 2 cases, in London, were reported to be fully vaccinated

Figure 1. Laboratory confirmed cases of measles by month of onset of rash or symptoms reported, London and England: January 2012 to March 2023

Across the WHO Europe Region there has been an increase in measles infections, with cases reported in 17 countries and numbers exceeding the total of 2022 by the end of February. Between April 2022 and March 2023 the vast majority of cases were reported in the Russian federation, Tajikistan and Turkey (2).

As a response to increasing numbers of confirmed infections, in England, UKHSA released a briefing note for health professionals in May, outlining the latest epidemiology and key actions needing to be taken to prevent a measles resurgence (3).

Measles activity is also picking up globally with outbreaks affecting many parts of Africa and South East Asia. WHO Europe has warned that a resurgence of measles is now an imminent threat, particularly due to the fall in vaccination rates during the COVID-19 pandemic (3).

All suspected cases of measles and rubella should be reported promptly to HPTs, a risk assessment conducted, and an OF kit sent for confirmatory testing even if local diagnostic testing is underway. This quarter, an OF sample was returned for only 49% of all suspected measles cases reported in England, well below the 80% WHO target (Table 1).

Mumps

In England, there were 51 laboratory confirmed mumps infections in the period January to March 2023 compared to 32 between October and December 2022, and 10 between July and September 2022 (1).

Only 14 of the 51 cases this quarter were in children and young adults below the age of 20 years. Of these, only 1 (1 out of 14) was vaccinated, while in the over 20-year-olds 22% (7 out of 37) were vaccinated.

Figure 2. Laboratory confirmed cases of mumps by quarter, England: January 2012 to March 2023

Rubella

There have been no new laboratory confirmed cases of rubella reported in the UK since 2019.

References

1. UKHSA (2023). Laboratory confirmed cases of measles, rubella and mumps, England: October to December 2022. Health Protection Report: volume 17 number 3

2. WHO Europe (2022). Measles and rubella monthly update: April 2023.

3. UKHSA (2023). Update on UK measles epidemiology and actions to prevent a measles resurgence. Health Protection Report: volume 17 number 5

4. US Centers for Disease Control and Prevention (2022). Progress toward regional measles elimination worldwide, 2000 to 2021. Mortality and Morbidity Weekly Report: volume 71, number 47, pages 1489 to 1495