The emergence of a deadly virus previously unseen in humans that has already
killed half those known to be infected requires speedy scientific detective work
to figure out its potential.
Experts in virology and infectious diseases say that while they already have
unprecedented detail about the genetics and capabilities of the novel
coronavirus, or NCoV, what worries them more is what they don't know.
The virus, which belongs to the same family as viruses that cause the common
cold and the one that caused Severe Acute Respiratory Syndrome (SARS), emerged
in the Middle East last year and has so far killed seven of the 13 people it is
known to have infected worldwide.
Of those, six have been in Saudi Arabia, two in Jordan, and others in Britain
and Germany linked to travel in the Middle East or to family clusters.
"What we know really concerns me, but what we don't know really scares me,"
said Michael Osterholm, director of the US-based Center for Infectious Disease
Research and Policy and a professor at the University of Minnesota.
Less than a week after identifying NCoV in September last year in a Qatari
patient at a London hospital, scientists at Britain's Health Protection Agency
had sequenced part of its genome and mapped out a so-called "phylogenetic tree"
- a kind of family tree - of its links.
Swiftly conducted scientific studies by teams in Switzerland, Germany and
elsewhere have found that NCoV is well adapted to infecting humans and may be
treatable with medicines similar to the ones used for SARS, which emerged in
China in 2002 and killed a tenth of the 8 000 people it infected.
"Partly because of the way the field has developed post-SARS, we've been able
to get onto this virus very early," said Mike Skinner, an expert on
coronaviruses from Imperial College London.
"We know what it looks like, we know what family it's from and we have its
complete gene sequence."
Yet there are many unanswered questions.
Spotlight on Saudi Arabia, Jordan
"At the moment we just don't know whether the virus might actually be quite
widespread and it's just a tiny proportion of people who get really sick, or
whether it's a brand new virus carrying a much greater virulence potential,"
said Wendy Barclay, a flu virologist, also at Imperial College London.
To have any success in answering those questions, scientists and health
officials in affected countries such as Saudi Arabia and Jordan need to conduct
swift and robust epidemiological studies to find out whether the virus is
circulating more widely in people but causing milder symptoms.
This would help establish whether the 13 cases seen so far are the most
severe and represent "the tip the iceberg", said Volker Thiel of the Institute
of Immunobiology at Kantonal Hospital St Gallen in Switzerland, who published
research this month showing NCoV grows efficiently in human cells.
Scientists and health officials in the Middle East and Arabian Peninsula also
need to collaborate with colleagues in Europe, where some NCoV cases have been
treated and where samples have gone to specialist labs, to try to pin down the
"One big virological blender"
Initial scientific analysis by laboratory scientists at Britain's Health
Protection Agency (HPA) - which helped identify the virus in a Qatari patient in
September last year - found that NCoV's closest relatives are most probably bat
It is not unusual for viruses to jump from animals to humans and mutate in
the process - high profile examples include the human immunodeficiency virus
(HIV) that causes AIDS and the newest H1N1 flu strain, which caused a pandemic
in 2009 and 2010.
Yet further work by a research team at the Robert Koch Institute at Germany's
University of Bonn now suggests it may have come through an intermediary -
In a detailed case study of a patient from Qatar who was infected with NCoV
and treated in Germany, researchers said the man reported owning a camel and a
goat farm on which several goats had been ill with fevers before he himself got
Osterholm noted this, saying he would "feel more comfortable if we could
trace back all the cases to an animal source.
"If so, it would mean the infections are just occasional crossovers from
animals, he said - a little like the sporadic cases of bird flu that continue to
pop up - and would suggest the virus has not yet established a reservoir in
Yet recent evidence from a cluster of cases in a family in Britain strongly
suggests NCoV can be passed from one person to another and may not always come
from an animal source.
An infection in a British man who had recently travelled to Saudi Arabia and
Pakistan was swiftly followed by two more British cases in the same family in
people who had no recent travel history in the Middle East.
The World Health Organization says the new cases show the virus is
"persistent" and HPA scientists said the cluster provided "strong evidence" that
NCoV, which like other coronaviruses probably spreads in airborne droplets, can
pass from one human to another "in at least some circumstances."
Despite this, Ian Jones, a professor of virology at Britain's University of
Reading, said he believes "the most likely outcome for the current infections is
a dead end" - with the virus petering out and becoming extinct.
Others say they fear that is unlikely."There's nothing in the virology that
tells us this thing is going to stop being transmitted," said Osterholm.
"Today the world is one big virological blender. And if it's
sustaining itself (in humans) in the Middle East then it will show up around the
rest of the world. It's just a matter of time."