Contracting measles increases vulnerability to other infections: research

  • Contracting measles increases vulnerability to other infections: research

Contracting measles increases vulnerability to other infections: research

A new analysis of 77 unvaccinated children from the Netherlands carried out by an worldwide team of researchers led by scientists at Harvard has found that the virus erases the body's memory of previous pathogens - effectively wiping its immunity memory. "Babies are more vulnerable to infections because their immune system is still maturing". This means measles survivors can remain susceptible to risky diseases - such as the flu and pneumonia - for years to come, despite having weathered their initial illness.

New Zealand is now in the midst of the most significant measles outbreak it has seen in more than two decades.

In 2015 he and some colleagues published a paper in Science suggesting the effect is lasting. But the results are another good reason to immunize children against the virus, the studies' authors and other infectious disease experts say.

The measles vaccine does not have this depletion effect, the researchers say.

On the other hand, says Jennifer Lighter, an infectious disease physician at New York University's Langone Health in New York City, "I think after you see your child that has measles, you wouldn't want your child to get other infections and to suffer needlessly". Vaccinations against measles prevented more than 21 million deaths between 2000 and 2017, according to the World Health Organization (WHO). A study published in May of this year found that measles weakened the immune system, but the exact mechanism was not understood. VirScan can detect antibodies to HIV, influenza, herpes, and hundreds of other viruses.

"Yet, it paradoxically leaves robust anti-measles immunity in its wake", Dr. Duane Wesemann, a professor of medicine at Brigham and Women's Hospital who was not involved in the work, wrote in a commentary accompanying the study in Science Immunology. So, while people who come down with measles are protected from future bouts of that virus, they seem to be left unprotected from other, previously known pathogens and ill-equipped to respond to new ones.

Researchers report the news October 31, 2019, in the journal Science.

In 2013, de Swart's team in Rotterdam had collected blood from unvaccinated children in an Orthodox Protestant community in the Netherlands, with consent from the kids' parents. During the outbreak, five of the children managed to avoid infection, but the other 77 contracted the virus. But sequencing revealed that the types of white blood cells weren't right.

After measles infection, the collection of antibodies kids had built up over their lifetime shrank - sometimes drastically. B-cells keep building these antibodies even after the pathogen clears, so the body "remembers" the disease if it ever returns.

Dr. Michael Mina, first author of the Harvard paper, said the phenomenon bears some similarities to the one that takes place after HIV infection.

Some families choosing not to vaccinate argue measles is just a pesky childhood illness to be endured. Even the USA, where most children are immunized, has seen a resurgence fueled by outbreaks in unvaccinated communities that in turn threaten people too young or sick to be immunized. The screening tool allowed the researchers to time-travel through the children's medical history and see what pathogens they'd encountered throughout their lives.

"The real takeaway is that underneath the surface, measles is much more than a rash, and it's much more than just an acute viral infection". It seems the measles virus essentially reduces its host's antibodies to other diseases, which makes a person more susceptible to infection. Depending on whether the infection was mild or severe, kids lost 33 or 40 percent of their total antibody collection.

The study "quite convincingly showed that this immune damage is likely the actual antibodies disappearing", Wesemann told Live Science.

The only way to prevent measles from erasing immune memory, Mina says, is the obvious one: Prevent cases by vaccinating. "It's like taking somebody's immune system and rewinding time, putting them at a more naïve state", Mina says. Although the relatively healthy Dutch children withstood these secondary infections, malnourished or immunocompromised children might not fare so well after measles, he added.

Wesemann wondered if antibody-replacement therapy, in which people receive antibodies from donors, might help sustain children after measles infection, while they build up their defenses once more.

Paradoxically, measles infections generate a very strong immune response against measles in the future, one that in the vast majority of cases protects for a lifetime.