Measles, mumps and rubella (MMR) are vaccine-preventable diseases. Despite the development of an efficient combined MMR vaccine, measles remains a major cause of mortality in developing countries and a cause of continuous outbreaks in Western countries. Measles, mumps and rubella are highly contagious and can be spread by droplets, sneezing, cough, saliva and aerosols.
As Belgium is involved in the WHO programme for the elimination of measles and rubella in Europe, a National Reference Centre for MMR (NRC MMR) has been established to perform laboratory testing on samples (serum, oral fluid and nasopharyngeal aspirates) of suspected clinical cases and to set out a nationwide surveillance system.
The NRC for Measles, Mumps and Rubella performs serological and molecular analyses on samples (serum, oral fluid and nasopharyngeal aspirates) from suspected clinical cases. Different ELISA’s (IgM, IgG and avidity testing) as well as PCR assays (virus detection) were optimized and validated according the ISO15189 norm.
In case of positive PCR results genotyping/sequencing assays are performed to determine the strain circulating in the population. Outbreak investigation is performed in collaboration with the unit Epidemiology of infectious diseases and the different regional health inspectorates to determine the index case, the transmission way and the origin of the outbreak strain.
This NRC is closely involved in the WHO programme for the elimination of measles and rubella in Europe by 2020. Hereto, a nationwide surveillance system has been established and non-invasive oral fluid assays have been developed. The advantage of oral fluid is that it is easy to sample, also by non-medical staff, and in children. Both antibodies (IgM and IgG) and virus (RNA) can be detected in oral fluid.
The NRC participates to a cross-sectional seroprevalence study in the Belgian general population for measles, mumps and rubella on about 3000 serum samples. These residual serum samples were collected in 2012 from different clinical laboratories.
The NRC has been involved in different outbreaks for measles and mumps. In 2007-2008 a measles outbreak occurred in the Orthodox Jewish communities in Antwerp and in this outbreak oral fluid sampling was applied for the first time for outbreak surveillance. In 2011, a measles outbreak occurred in anthroposophic schools in Ghent and other outbreaks were notified in the rest of Belgium. Oral fluid sampling gave us again the opportunity to define the circulating strains. In 2013, a mumps outbreak occurred in different universities in Belgium, starting in Ghent. In 2016 — 2017, measles outbreaks are still going on and continue to cause a threat to public health. Outbreaks are facilitated by suboptimal vaccination rates in certain populations, increased migration and travel. The vaccination coverage of the Belgian population needs to be further improved, especially for the second dose of the vaccine, in order to reach our WHO elimination goal.