The Central nervous system (CNS) may be at risk as the nose and mouth become the most favourable entry points for the novel coronavirus causing symptoms like loss of smell and taste, shows the study conducted by scientists at Indian Institute of Technology (IIT), Jodhpur. The virus upon entering the nose or mouth may slowly move to the olfactory bulb of forebrain through the neurons of the olfactory mucosa that is chiefly responsible for the sense of smell, found the study currently accepted by the journal ACS Chemical Neuroscience.
The lead researcher Dr Surajit Ghosh and his team pointed out that a specific human receptor known as human angiotensin-converting enzyme-2 (hACE2) which is highly susceptible to the COVID-19 virus SARS-CoV-2 allowing the virus to enter the host cells was also found in the brain. hACE2 receptors are commonly found in many areas in the body including the lung parenchyma and nasal mucosa.
The CT and MRI scans of the brain of COVID-19 patients involved in the study showed a rare encephalopathy called acute necrotizing encephalopathy (ANE), which revealed the presence of hACE2 receptors in the brain. The study highlighted that the entire CNS and the underlying structures in the brain may thus become more prone to viral infection causing brain dysfunction with seizures and mental disorientation.
The virus may also infect the brain through other peripheral nerve terminals or simply blood circulation by breaching the blood-brain barrier, suggests the researchers.
Furthermore, the study also highlighted the therapeutic role of peptide-based molecules in preventing the interaction between viral spike proteins and the hACE2 receptors to prevent the virus from entering the cells.
“The pathway of infection of SARS-CoV-2 and its impact on various organs is an important area that would also help with the future rational approaches for therapy. The neuro-invasive nature of the virus and its effects on the senses of smell and taste are thus interesting and useful areas of investigation,” said Professor Ashutosh Sharma, Secretary, DST.
The researchers also warn that smoking can increase the susceptibility of the individuals to contract COVID-19 infection as it stimulates the co-expression of the hACE2 receptor and the nicotinic receptor.
The scientists exhort the asymptomatic carriers of COVID-19 with anosmia (loss of smell) and ageusia (loss of taste) to self-quarantine and consult specialized neurologists before they turn into carriers. Knowing about symptoms encountered by the infected patients can help other patients in making earlier diagnosis and treatment and prevent the spreading of the disease. Dry cough, fever and shortness of breath are some of the other very common symptoms of COVID-19.
However, another mysterious symptom known as “COVID toes” where the toes and fingers appear with red or purple mottling giving a frostbite appearance was described by a group of Italian doctors earlier in March.
The symptom which has recently started to show up more frequently may be an apparent sign of coronavirus infection in otherwise asymptomatic children and young adults, suggests experts.
“They’re typically painful to touch and could have a hot burning sensation,” Dr Ebbing Lautenbach, chief of infectious disease at the University of Pennsylvania’s School of Medicine, told USA Today. “This is a manifestation that occurs early on in the disease, meaning you have this first, then you progress. Sometimes this might be your first clue that they have COVID when they don’t have any other symptoms.”
People with this symptom alone may not even test positive for coronavirus, as it is often in its early stages at that point, told Dr Lautenbach.