Measles: high risk of delayed fatal consequences07/16/2013
After a measles infection, infants in particular are at high risk of developing a fatal encephalitis, even years later. A new study has now revealed that this risk is significantly higher than assumed.
“Measles used to be one of the deadliest and most feared diseases in the world. Then along came the vaccination, and the horror of this supposed childhood illness was forgotten. Now the viruses are spreading again, in Germany as well – as a delayed consequence of vaccination fatigue and misinformation.” This was the headline of a recent article in the news magazine Der Spiegel about the “delayed consequences of vaccine fear”. The article drew on the news of measles outbreaks in Bavaria, Berlin, and North Rhine-Westphalia.
Now, scientists from the University of Würzburg and the Bavarian Health and Food Safety Authority (LGL) in Oberschleißheim have revealed that a measles infection, especially in infants, is associated with a high risk of fatal complications. Whereas it was previously assumed that a specific delayed complication of measles occurs in one in every 100,000 cases, they calculated the average risk for children below 5 years of age to be 1 in 3,300. The researchers have published their study in the scientific journal PLOS One.
SSPE: the dreaded delayed complication
Subacute Sclerosing Panencephalitis (SSPE): this is the medical name for the dreaded delayed complication of a measles infection – an inflammation of the brain. “SSPE mainly affects children and does not tend to develop until several years after an acute measles infection. It leads to a gradual loss of all mental faculties and culminates in a vegetative state, in which the sufferer dies after a few months or even years. There is no treatment for SSPE,” is how Benedikt Weißbrich describes the symptoms of this disease. Weißbrich is a Research Associate at the University of Würzburg’s Institute of Virology and Immunobiology and one of the coordinators of the study.
In older literature, the risk of occurrence of SSPE after acute measles was cited as 1 in 100,000. “However, more recent studies from Great Britain and the USA suggest that the risk is far greater,” says Weißbrich. It is possible that the risk may have increased over time. Though, it is just as conceivable that the case numbers were not previously recorded properly, particularly for very young children. It is in fact difficult to calculate the SSPE risk because the time between an acute measles infection and the development of SSPE may span many years.
31 SSPE cases in six years
There was no relevant data for Germany. For this reason, the Institute of Virology and Immunobiology at the University of Würzburg and the Bavarian Health and Food Safety Authority conducted a joint study and examined the SSPE risk.
“We recorded SSPE cases in children who had been treated in German hospitals between 2003 and 2009,” explains Weißbrich. The SSPE cases diagnosed at the University of Würzburg and the German Pediatric Surveillance Unit (ESPED) were used as the data source. A total of 31 children with a diagnosis of SSPE were identified by the researchers. To enable them then to calculate the SSPE risk, they next had to find out when and where these children had been infected with measles. “This information was admittedly patchy, but for 13 children it was fair to assume that they had become infected with measles in Germany between 1994 and 2001,” says Weißbrich. All the children were below the age of five at the time of their measles infection.
The scientists were able to extrapolate the total number of measles cases during this period from hospital statistics for the relevant age group. The figure was 42,600. This produced an SSPE risk of 1 in 3,300 after measles virus infections in the first five years of life.
Fatal consequences for the first year of life
“Our study provides data for the very first time on the incidence of SSPE cases in Germany and reveals that the risk of SSPE with measles infections in the first few years of life is considerable and certainly not negligible,” concludes Weißbrich. What is more, the study shows that the calculated average risk of 1 in 3,300 for the under-five age group is probably much higher for children in the first year of life and correspondingly lower for children in the fifth year of life.
The implications of this are significant: a measles vaccination protects against SSPE, but it is not administered until after a child is eleven months old. “This means that the very children for whom the SSPE risk is highest, children in their first year of life, cannot be protected against SSPE by a measles vaccination,” warns Weißbrich and therefore urgently appeals to all parents to have their children vaccinated. “Only if as many people as possible are immune to measles will it be possible to eliminate this disease and thereby protect children in the first year of life from a terrible disease,” says the researcher. However, current reported data with more than 1,000 cases of measles already in 2013 reveal that Germany still has a long way to go.
Measles is a viral infection from which more than 100,000 children worldwide still die annually. In Germany, too, there continue to be deaths from measles. These are partly due to complications caused by the measles infection, which occur during an acute attack, such as encephalitis and pneumonia. Another reason is that the measles virus causes the encephalitis SSPE, described above, as a delayed complication that is almost always fatal.
Schönberger K, Ludwig M-S, Wildner M, Weissbrich B (2013) Epidemiology of Subacute Sclerosing Panencephalitis (SSPE) in Germany from 2003 to 2009: A Risk Estimation. PLoS ONE 8(7): e68909. doi:10.1371/journal.pone.0068909
Dr. Benedikt Weißbrich, T: +49 (0)931 201-49962; e-mail: firstname.lastname@example.org