It’s official: CoV behaves like SARS, has its origin from bats, spreads
like large droplets and from people having lower respiratory infections AND so preventable
to an extant
Dr KK Aggarwal
President CMAAO, HCFI and past National President IMA
Every decade a zoonotic coronavirus crosses species to infect
human populations and in this decade we have a virus, provisionally called
2019-nCoV, first identified in Wuhan, China, in persons exposed to a seafood or
wet market.
In earlier two decades we had outbreaks caused by two other
pathogenic human respiratory coronaviruses (severe acute respiratory syndrome
coronavirus [SARS-CoV] and Middle East respiratory syndrome coronavirus
[MERS-CoV]), causing respiratory disease that is often severe. In the current situation
the mortality rate is 3%.
Scientists have identified and characterized 2019-nCoV. The
viral genome has been sequenced. The virus is 75 to 80% identical to the
SARS-CoV and even more closely related to several bat coronaviruses.
It can be propagated in the same cells that are useful for
growing SARS-CoV and MERS-CoV, but notably, 2019-nCoV grows better in primary
human airway epithelial cells than in standard tissue-culture cells, unlike
SARS-CoV or MERS-CoV.
Both SARS-CoV and MERS-CoV infect intrapulmonary epithelial
cells more than cells of the upper airways. Consequently, transmission
occurs primarily from patients with recognized illness and not from patients
with mild, nonspecific signs. It appears that 2019-nCoV uses the same
cellular receptor as SARS-CoV (human angiotensin-converting enzyme 2 [hACE2]), so
transmission is expected only after signs of lower respiratory tract disease
develop.
It is likely that 2019-nCoV will behave more like SARS-CoV.
Given its close similarity to bat coronaviruses, it is likely
that bats are the primary reservoir for the virus. SARS-CoV was transmitted to
humans from exotic animals in wet markets, whereas MERS-CoV is transmitted from
camels to humans. In both cases, the ancestral hosts were probably bats.
Transmission of 2019-nCoV probably occurs by means of large
droplets and contact and less so by means of aerosols and fomites, on the
basis of our experience with SARS-CoV and MERS-CoV.
Public health measures, including quarantining in the community
as well as timely diagnosis and strict adherence to universal precautions in
health care settings, were critical in controlling SARS and MERS. [ Excerpts from NEJM]
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