Measles can cast a long shadow, even after an apparent full recovery
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Measles can cast a long shadow, even after an apparent full recovery
Measles can cast a long shadow, even after an apparent full recovery
Sarah BodenToday at 2:52 p.m.
Measles
Five people have died from measles-associated causes in the United States this year. This fatality rate suggests there may have been 5,000 to 15,000 infections in 2026, since one to three of every 1,000 children who become infected with measles will likely die from respiratory and neurologic complications, according to the Centers for Disease Control and Prevention (CDC). The CDC's current 2026 measles case tally is 3,887.
Loss of life in the weeks following an infection is just one of the devastating outcomes of measles. But even a relatively mild case of measles can result in long-term health consequences that are painful and devastating. These include acute disseminated encephalomyelitis (ADEM), immune amnesia, and subacute sclerosing panencephalitis (SSPE).
The good news is that two doses of the measles, mumps, and rubella (MMR) vaccine are 97% effective against the virus and the risk of life-altering complications.
Acute disseminated encephalomyelitis—immune overreaction
Sudden inflammation of the central nervous system can strike as late as three or four weeks after an initial infection from illnesses such as measles, mumps, or even the flu. Symptoms are similar to those of multiple sclerosis.With ADEM, the immune system overreacts and attacks tissue in the brain or spinal cord, Andrew Pavia, MD, a pediatric infectious disease epidemiologist at the University of Utah, told CIDRAP News.
"Most often this is the myelin in the white matter, or insulation, of the brain," he said.
For measles, the ADEM incidence rate is one out of every 1,000 cases. Some vaccine skeptics will note that ADEM is a rare side effect of the MMR, though this occurs in just one to two out of every million vaccinations. On balance, vaccination against measles lowers the risk of this neurological complication.
Treatment for ADEM includes steroids, intravenous immunoglobulin infusions, and therapeutic plasma exchange. Most people completely recover, though nearly a quarter of the 77 children in the 2022 study who had moderate to severe cases of ADEM had lasting health issues.
Pavia said the most common long-term problems after ADEM are motor weakness, cognitive impairment, and seizures. Other concerns include vision loss and possible behavioral or emotional problems.
In some instances, ADEM is fatal, as was the case in the recent measles-associated death of an 18-year-old man in Pennsylvania.
Immune amnesia—affects up to 73%
The immune system is like a memory bank. Every vaccination or recovery from infection is a deposit that's filed away. Then when someone encounters certain pathogens in the future, the immune system remembers how to fight them off.But measles can wipe out that memory bank, erasing as much as 73% of someone's hard-won immunity, according to a 2019 paper in Science. This leaves patients vulnerable to secondary infections while fighting off measles, and means they'll likely be sicker in the future.
Michael J. Mina, MD, PhD, co-author of the Science study, recently told CIDRAP News that he expects thousands of additional clinical visits in the United States in the coming years due to the country's soaring number of measles infections.
For adults, immune amnesia can mean they end up going a second round with childhood illnesses like chickenpox or Epstein-Barr virus, the most common cause of infectious mononucleosis. That second round can be tougher, as these illnesses generally are more severe in adults than kids.
In Pennsylvania, which has the most measles infections seen in any state in 35 years, two out of every three cases have been among adults.
Everyone who survives measles experiences some level of immune amnesia. It can take up to five years for the immune system to fully recover.
Subacute sclerosing panencephalitis—a 'potential time bomb'
This deadly neuroinflammatory disease is "the most enigmatic and terrifying consequence of measles," said Pavia.SSPE is caused by the persistent presence of measles viruses in the central nervous system that have mutated, allowing them to evade the immune system. Symptoms may not appear until seven to 10 years after an initial measles infection in patients who seem to have fully recovered.
The first signs are personality changes and mood swings, along with headaches. SSPE progresses to uncontrolled movements, such as jerking and muscle spasms, as well as vision loss, seizures, and dementia.
The jerking movements are then replaced by involuntary twisting and rigidity. Eventually, the infection spreads to the parts of the brain that control breathing, heart rate, and blood pressure, resulting in coma and eventually death.
Once symptoms appear, the entire disease course can take several years, sometimes longer. There is no cure. SSPE is always fatal.
Among people who contracted measles during a resurgence in the United States from 1989 to 1991, the CDC reports that seven to 11 out of every 100,000 were estimated to be at risk for developing SSPE.
However, people who contract measles as infants appear to have a higher risk of developing SSPE. A 2016 review of California health records puts the incidence rate at one out of 609 cases of measles if contracted before 12 months of age.
A child in Los Angeles died of SSPE last year due to an infection acquired as an infant before being eligible for the MMR vaccine. The first dose is generally given from 12 to 15 months of age.
Given the number of measles infections that have already occurred in the United States in the past two years—almost 6,200 and counting—and that case counts are expected to climb over the winter months, Pavia warns that SSPE "is a potential time bomb."