A study published Monday revealed that the new coronavirus can enter the human brain through the nose. This finding may help explain some of the neurological symptoms seen in Covid-19 patients and inform the diagnosis and measures to prevent infection.
The study, conducted by researchers from Charite-Universitatsmedizin Berlin, Germany, was published in the journal Nature Neuroscience.
According to the study, the SARS-CoV-2 or Covid-19 virus not only affects the respiratory tract, but also affects the central nervous system (CNS). This eventually results in neurological symptoms such as loss of smell, taste, headache, fatigue and nausea, he noted.
“There is growing evidence that SARS-CoV-2 not only affects the respiratory tract but also affects the CNS, resulting in neurological symptoms such as loss of smell and taste, headache, fatigue, nausea and vomiting in more than a third of people with COVID-19,“said the study.
Although recent research has described the presence of viral RNA in the brain and cerebrospinal fluid, it is unclear where the virus enters and how it is distributed within the brain, the Press Trust of India (PTI) news agency reported.
The researchers examined the nasopharynx, the upper part of the throat that connects to the nasal cavity, a likely first site of viral infection and replication, and the brains of 33 patients (22 men and 11 women) who died with the coronavirus infection. .
The median age at death was 71.6 years, and the time from onset of Covid-19 symptoms to death was a median of 31 days, the researchers said according to PTI.
The researchers said they found the presence of SARS-CoV-2 RNA, the genetic material of the coronavirus, and proteins in the brain and nasopharynx. Intact viral particles were also detected in the nasopharynx, they said.
The highest levels of viral RNA were found in the olfactory mucous membrane, they said.
Furthermore, the duration of the illness was inversely correlated with the amount of detectable virus. This indicated that higher levels of SARS-CoV-2 RNA were found in cases with a shorter duration of illness.
The team also found SARS-CoV-2 spike protein in certain cell types within the olfactory mucosa layer, where it can take advantage of the proximity of endothelial and nerve tissue to enter the brain.
In some patients, SARS-CoV-2 spike protein was found in cells expressing neuron markers, suggesting that olfactory sensory neurons may be infected, as well as in areas of the brain that receive smell and taste signals, the researchers said.
SARS-CoV-2 was also found in other areas of the nervous system, including the medulla oblongata, the brain’s main center of respiratory and cardiovascular control, they said.
The researchers noted that more Covid-19 autopsy studies including a wide range of samples are needed to identify the precise mechanisms that mediate the virus’s entry into the brain and examine other possible ports of entry.
(With PTI inputs)
