Khaberni - A Brazilian study has shown that tissues such as the tonsils and adenoids can serve as a reservoir for the Rhinovirus, the primary cause of colds and most respiratory infections worldwide.
The study conducted by the University of São Paulo (USP) relied on samples taken from 293 children who underwent surgical removal of the tonsils and adenoids due to snoring, sleep apnea, or recurrent infections.
At the time of surgery, none of the children displayed symptoms, yet researchers discovered the virus in 46% of them, either in the tonsils, adenoids, or nasal secretions.
How does the virus hide from the immune system?
Scientists previously believed that the Rhinovirus only infected the superficial layer of the nasal and throat mucous membrane, then penetrated the cell and forced it to produce copies of itself until it burst, alerting the immune system which would eliminate it within 5 to 7 days.
However, the new discovery clarifies that the virus can reach deep layers of the tonsils and adenoids, infecting B lymphocytes (responsible for producing antibodies) and helper T lymphocytes (which lead the immune response). Instead of killing these cells, the virus remains inside them for a long period in a dormant state, thereby resembling the behavior of herpes viruses and the human papillomavirus.
The relationship between asthma attacks and middle ear inflammation
Researcher Yuriko de Aruda Neto, the study's coordinator, says, "I have the impression that regardless of the common virus we are investigating, we will find it in lymphoid tissues. These tissues are like a 'garden' for viruses, which can be beneficial as it enhances immune memory, but it can be problematic in some cases."
In patients with asthma, the hidden viruses in lymphocytes can release inflammatory substances that reach the lungs and cause asthma attacks, which explains why colds are among the most common triggers of asthma attacks in young children.
Similarly, the presence of viruses in the adenoids (located near the Eustachian tube) could explain some children's recurring middle ear infections, where the virus moves from the adenoids to the middle ear causing inflammation that blocks the narrow channel and leads to fluid accumulation and bacterial growth.
The challenge of diagnosis and risks to immunodeficient patients
Aruda warns that tests conducted on nasal secretions may not always reflect the truth; a child with pneumonia might test positive for the Rhinovirus from a previous infection, not the actual virus causing the inflammation in the lungs.
Another hypothesis that the team seeks to test is whether dormant viruses in lymphoid tissues can reactivate when the immune system is weakened, as happens with bone marrow transplant patients who develop severe pneumonia. The virus may not have entered from outside, but was already present in the tonsils and adenoids and reactivated due to immune weakness.
