People who get measles suffer more infections up to five years after infection. Now, two new investigations explain why and confirm how this disease is able to paralyze defenses against viruses and bacteria in the long term, creating an 'immunological amnesia' that leaves individuals unprotected against other pathogens.
Cough, rashes and fever, even life-threatening complications, such as pneumonia and encephalitis, an inflammation of the brain, are effects of the measles virus, which in 2017 caused
110,000 deaths worldwide despite the existence of a safe and economical vaccine.
Two studies published in Science and Science Immunology once again emphasize not only the need for a generalized vaccination that prevents this infection, but also that prevents the weakening of collective immunity – the protection of a group thanks to a critical mass that is immune- against other types of pathogens.
"This is the first time that genetics are used to create a map of the immune system in response to measles. This allowed us to respond to how it causes this immunosuppression and why people suffer more infections up to five years after contracting it," he explains to Sync
Velislava Petrova, one of the authors.
The first paper analyzes the immune system of 77 children in the Netherlands (between 4 and 17 years) not vaccinated before and after measles infection in an outbreak that spread throughout their community. The average time between the collection of both samples was 10 weeks.
The results reveal that the infection can paralyze immunity against viruses and bacteria in the long term, which will lead to an 'immunological amnesia' that will make individuals more vulnerable to future infections, including viruses with which it has already been had contact
Thus, although the team had no trouble seeing antibodies against measles, the rest seemed to be disappearing. In fact, the antibodies that children had accumulated throughout their lives were significantly reduced.
"We have found strong evidence that measles destroys the immune system," explains Stephen Elledge, co-author of the work and researcher at the Howard Hughes Medical Institute (USA). "When this virus attacks, the antibodies disappear."
The hypothesis that the virus erases the body's memory of previous pathogens has already been supported by previous research, which associated measles with up to 50% of childhood deaths from infectious diseases, but it was missing to know how it occurs.
In this study, the authors observed that measles eliminated, two months after infection, between 11 and 73% of the protective antibodies of children, that is, blood proteins that "remember" previous encounters with viruses and They help the body avoid repeated infections.
The researchers also conducted the experiment in four macaque monkeys, this time collecting blood samples before and up to five months after infection. The monkeys lost, on average, between 40 and 60% of the antibodies that protect them from other pathogens. However, no decrease in antibodies was observed in babies vaccinated against measles, mumps and rubella.
According to the authors, although the reconstruction of the antibody repertoire is possible by reexposing the pathogens, this could take months or years and could pose several health risks.
"The virus is much more harmful than we thought, so vaccinate your children," says Elledge. "And if they have skipped the vaccine and become infected with measles, they may need to be revaccinated from previous diseases."
An immature baby's immune system
Meanwhile, research published in Science Immunology explains why children often get other infectious diseases after measles. The authors, from the Wellcome Sanger Institute in the United Kingdom and the University of msterdam, confirmed that this virus eliminates part of the memory of the immune system, destroying previous immunity.
In addition, the team demonstrated for the first time that measles readjusts the human immune system and returns it to a state similar to that of an immature baby, with a limited ability to respond to new infections.
To reach this conclusion, they sequenced antibodies produced by B lymphocytes – one of the primary immune cells capable of recognizing and attacking a virus – in 26 children not vaccinated before and about 40 days after infection in three Protestant Orthodox schools in the Passes Low.
When comparing the data, the researchers identified two points that warned about measles immunosuppression: an incomplete reposition of the B lymphocyte pool and compromised immune memory due to the depletion of the clones of these cells. In some children the effect was similar to receiving potent immunosuppressive medications.
"This study is a direct demonstration in humans of 'immunological amnesia', in which the immune system forgets how to respond to the infections found above," Velislava Petrova, who works at the British institution, tells SINC.
"It means that in some individuals measles will not only erase our immunological memory, but limit our ability to build a new immunity," he adds.
In additional studies in ferrets, scientists found that animals infected with measles already vaccinated against the flu became less immune to the virus and experienced more severe symptoms at the time of this secondary infection.
The reduction in vaccination rates is causing an increase in measles cases, which could also lead to an increase in other dangerous infections such as influenza, diphtheria or tuberculosis, even in people who were previously immune. This research has great implications for public health, as it demonstrates that vaccination against measles not only protects against this virus, but also against other diseases.
"To maintain collective immunity, the vaccination rate in a country must be at least 95%, since measles is very contagious. Parents should be aware that their choice to not vaccinate their children may also have consequences for the health of other people, "Petrova concludes.
More than 20 million lives saved
Before the development of the vaccine in 1963, almost all children suffer from infection. According to the World Health Organization (WHO), vaccination
It has helped reduce measles cases by 80% between 2000 and 2017, which has saved some 21.1 million lives.
However, due to a combination of anti-vaccination campaigns, religious communities that limit immunization and limited access to the vaccine, measles continues to affect more than seven million people a year worldwide.
Vaccination reduction alone has resulted in an almost 300% increase in measles infections since 2018. In 2019, the U.S. Centers for Disease Control and Prevention has reported 1,250 cases to the past. October 3.
. Measles virus destroys the memory of the immune system – LA NACION