INSUBCONTINENT EXCLUSIVE:
Kathmandu, May 8
Highlights:& People living in altitude of over 2,500 metres are less susceptible to COVID-19& Fewer highland inhabitants
may have contracted COVID-19 due to hypoxia& High-altitude environmental factors may have reduced the virulence of COVID-19
There good news
for people living in high altitudes: they may be less susceptible to coronavirus infection
That the finding of the paper titled, ‘Does the pathogenesis of SAR-CoV-2 virus decrease at high-altitude?&, available in the National
Library of Medicine of the United States.
This paper, written by Christian Arias-Reyes of University Institute of Cardiology and Respirology
of Quebec, Canada, et al, has analysed epidemiological data of the Tibetan region of China, Bolivia and Ecuador.
The paper has defined
high-altitude inhabitants as those living in altitudes of over 2,500 metres above the sea level
This means Nepalis living in places like Mustang, Manang and certain parts of Dolpa, to name a few, are less likely to contract the deadly
coronavirus disease, which has so far killed over 257,000 and infected more than 3.7 million worldwide.
The reason for decreased severity of
the global COVID-19 outbreak at high altitude could be related to environmental factors, says the paper.
A high-altitude environment is
characterised by &drastic changes in temperature between night and day, air dryness, and high levels of ultraviolet (UV) light radiation&
with &UV radiation acting as a natural sanitizer&
&These factors may dramatically reduce the survival capacity of the virus at high-altitude, and therefore its virulence,& says the paper
&Finally, due to the lower density of air and greater distance between molecules at high-altitude, the size of the airborne virus inoculum
must be smaller than at sea level.&
These characteristics may provide explanation to why more coronavirus cases are being detected in
lowlands, such as Udaypur and Nepalgunj, of Nepal
Nepal has detected 101 coronavirus cases so far, of which over 90 per cent are from Tarai, located at an altitude of up to 300 metres, and
inner Tarai.
Like in Nepal, the study found that COVID-19 infection rates were very low in highlands of China, Bolivia and Ecuador
In the plateau region of China, which covers Tibet, Qinghai and part of Sichuan, only 134 confirmed cases have been reported, which is
drastically low than in other parts of the country
The results were similar in Bolivia and Ecuador
Bolivia reported three-fold lower cases in high-altitude regions than in lowlands, whereas Ecuador registered four-fold less COVID-19 cases
in high-altitude areas than in lowlands.
&Although these results are encouraging, the bitter truth is that not many Nepalis live in
high-altitude areas [because of limited access to road network, markets and various amenities]
So the study is not relevant for Nepal,& said Dr Kiran Raj Pandey, a physician and public health expert currently associated with HAMS
Hospital.
Although over 1,200 settlements are located at altitude of over 3,000 metres in Nepal, half of the Nepalis live in lowlands called
Another 43 per cent of Nepalis live in hilly areas, like Kathmandu and Pokhara, which are located at an altitude of around 1,400 metres
But the study in Bolivia found that people living in altitude of 1,866 metres in a city called Tarjia had reported relatively little
transmission of disease.
So why is transmission of COVID-19 low in highlands?
COVID-19 is an infection caused by coronavirus
The outer layer of the coronavirus consists of spike proteins
Once the virus enters the body, the spike proteins look for receptor called angiotensin-converting enzyme 2 (ACE-2) in human cell
ACE-2 allows the virus to enter the human cell
Once inside, the virus releases its RNA, turning the human cell into a factory to produce more coronavirus
This completely destroys the human cell
Once the cell is destroyed, the viruses then move out to other cells to repeat the process of generating more coronavirus.
This means
&reducing the activity of ACE-2 in [human] cell membranes could theoretically reduce the ability of SARS-CoV-2 to penetrate [human] cells,
And high altitude does just that
It makes ACE-2 less active while making ACE-1 more energetic
ACE-1 generally becomes more receptive when there is deficiency in the amount of oxygen that reaches the tissues — a medical condition
known as hypoxia.
&ACE-1 is upregulated by the hypoxia-inducible factor 1 (HIF-1), a master regulator of the response to hypoxia, in human
pulmonary artery smooth muscle cells,& says the paper, adding, &Similar results were obtained in rats exposed to conditions equivalent to
After 28 days in that altitude, the heart cells of rats showed increased levels of ACE-1 and decreased expression of ACE-2.&
These findings
suggest that high-altitude inhabitants &express reduced levels of ACE-2 in their lungs and other tissues&
&Thus, adaptation to high-altitude environment could render local inhabitants less susceptible to SARS-CoV-2 virus and consequently are
protected from the development of the disease defining acute respiratory distress syndrome,& says the paper.
The post Highlanders less
susceptible to coronavirus infection: Study appeared first on The Himalayan Times.
