• Posted December 26, 2023

In Rare Cases, Measles Mutates in Brain and Kills

Measles is incredibly contagious, and outbreaks are more common now as people decide against vaccinating their kids.

Now, a case involving a rare but fatal brain disease caused by the measles virus may make some rethink that decision.

The patient caught measles as a child. It took years for the virus to migrate to their brain, where it mutated and caused the fatal illness, according to Mayo Clinic researchers.

"Our study provides compelling data that shows how viral RNA mutated and spread throughout a human organ -- the brain, in this case," said Mayo virologist and study co-lead author Roberto Cattaneo.

Reporting Dec. 21 in the journal PLOS Pathogens, Cattaneo's team explained that while the measles virus initially congregates in the respiratory tract, it can slowly migrate throughout the body years after the illness is over.

The brain disease, called subacute sclerosing panencephalitis (SSPE), occurs in about 1 in every 10,000 measles cases, the researchers said.

They estimate that it takes about 10 years for the virus to make its way to the brain, where it can begin to mutate.

Seizures, memory impairments and mobility issues can signal the onset of SSPE.

In the new study, Cattaneo's team examined the brain of a person who died from the disease. They looked at the genetics of tissues taken from 15 different brain regions.

The measles virus' genome appears to begin to alter in dangerous ways once it infiltrates the brain, the research showed. This happened over and over in this patient, and "two specific genomes had a combination of characteristics that worked together to promote virus spread from the initial location of the infection -- the frontal cortex of the brain -- out to colonize the entire organ," Cattaneo explained in a Mayo news release.

In past years, when U.S. measles vaccination rates were extremely high, SSPE wasn't thought of as a major threat. But during the pandemic, many kids missed out on getting immunized and cases jumped 18%, the Mayo team noted.

According to data from the U.S. Centers for Disease Control and Prevention, deaths from measles in 2021 also rose by 43% compared to cases seen in 2022, when vaccinations began to rise again.

Years from now, "we suspect SSPE cases will rise again as well," said study co-lead author Iris Yousaf.

"This is sad because this horrible disease can be prevented by vaccination," said Yousaf, who is a a fifth-year graduate student at the Mayo Clinic Graduate School of Biomedical Sciences.

At least now,"we are in the position to study SSPE with modern, genetic sequencing technology and learn more about it," she added.

Cattaneo is optimistic about this research, as well. He believes that investigations being conducted at Mayo and elsewhere "may facilitate the generation of effective antiviral drugs" that can help save people stricken with SSPE.

More information

Find out more about SSPE at the National Institute of Neurological Disorders and Stroke.

SOURCE: Mayo Clinic, news release, Dec. 21, 2023