[A group of Chinese experts this week isolated and obtained the genome sequence of the new virus, which is believed to be responsible for sickening dozens of people who visited a wild-animal market last month in Wuhan, in central China, state media reported Thursday.]
By Gerry Shih and
Lena H. Sun
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Health
officials run thermal scans on passengers arriving from Wuhan, China,
at
Bangkok’s Suvarnabhumi Airport on Wednesday. (Lauren Decicca/
AFP/Getty
Images)
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BEIJING
— Chinese researchers
investigating the cause of a mysterious pneumonia outbreak have discovered a
new strain of coronavirus, a species of viruses that can cause deadly illnesses
such as severe acute respiratory syndrome (SARS) and Middle East respiratory
syndrome (MERS), according to Chinese state media and the World Health
Organization.
A group of Chinese experts this week isolated
and obtained the genome sequence of the new virus, which is believed to be
responsible for sickening dozens of people who visited a wild-animal market
last month in Wuhan, in central China, state media reported Thursday.
The outbreak ahead of the Lunar New Year
travel season in China has prompted health authorities across East Asia to
increase screening of travelers for signs of fever, underscoring fears about
its potential spread.
A Chinese preliminary assessment panel
isolated the coronavirus — named for its crown-like appearance under a
microscope — from samples taken from a single patient’s lung fluid, blood and
throat swabs, the panel’s leader, Xu Jianguo, told the official Xinhua News
Agency in an interview.
“The expert group believes that the pathogen
of the unexplained cases of viral pneumonia has been preliminarily identified
as a new type of coronavirus,” Xu said. “The virus was isolated from samples
and showed a typical coronavirus appearance under an electron microscope.”
[Specter of possible new virus emerging from central China raises alarm across Asia]
Developing specific drugs and vaccines
against a new pathogen could take years, he said.
In a statement, the WHO said initial
information about the Wuhan cases it obtained from Chinese authorities pointed
to a coronavirus — a family of viruses that can cause the common cold, as well
as SARS and MERS. There is no vaccine or treatment for SARS or MERS, which are
epidemic threats.
“According to Chinese authorities, the virus
in question can cause severe illness in some patients and does not transmit
readily between people,” it said.
Coronaviruses cause illnesses of differing severity,
the WHO said. Some transmit easily. Novel coronaviruses emerge periodically,
with SARS emerging in southern China in 2002 and MERS a decade later.
SARS caused 774 deaths, while MERS, first
reported in Saudi Arabia, has killed 851 people.
As surveillance improves, more coronaviruses
are likely to be identified.
The WHO said more-comprehensive information
is required to confirm the pathogen and to better understand the epidemiology
of the outbreak, the clinical picture, the investigations to determine the
source, how the illness is spread and the extent of infection.
In its statement Thursday, the WHO praised
China for its efforts thus far. Public health experts have raised concerns
about the lack of predictable and daily communication from Chinese leaders in
charge of the response about what is known and remains unknown about the
outbreak.
Chinese investigators conducted gene
sequencing of the virus using an isolate from one positive patient sample.
“Preliminary identification of a novel virus in a short period of time is a
notable achievement and demonstrates China’s increased capacity to manage new outbreaks,”
the WHO said.
China has “strong public health capacities
and resources to respond and manage respiratory disease outbreaks,” the WHO
said. In addition to treating the patients in care and isolating new cases as
they are identified, the WHO said, Chinese public health officials “remain
focused on continued contact tracing, conducting environmental assessments at
the seafood market, and investigations to identify the pathogen causing the
outbreak.”
The WHO also said it continues to monitor the
situation closely and, together with its partners, is ready to provide
technical support to China to investigate and respond to the outbreak.
Symptoms of the new Wuhan pneumonia include
fever and invasive lesions on the lungs when viewed on chest radiographs.
The U.S. Centers for Disease Control and
Prevention issued a health advisory Wednesday to clinicians about screening
patients with severe respiratory symptoms for travel history to Wuhan.
Among the chief concerns about the outbreak
is how readily this respiratory illness spreads from one person to another. So
far, there have been no reports of infection among health-care workers treating
patients or among family members who have not had the same exposure to the
source, infectious-disease experts said.
“Then the level of concern is somewhat
reduced, although it can always happen later and infections can change,” said Jeremy
Farrar, director of the Wellcome Trust, a London-based global biomedical
research charity.
“In Wuhan, there has not been a new confirmed
case for around two weeks and the evidence does not suggest any human to human
transmission,” he said in a statement. “Both of these are every reassuring for
now.”
If the new virus is behaving like MERS, there
could be some limited human-to-human transmission, which could explain why
there have been clusters of cases in hospitals, said Andrew Rambaut, an
infectious-diseases professor at the University of Edinburgh whose research
focuses on the evolution of emerging viral pathogens in humans.
That could be from ill people in hospitals
infecting one another, he said. Those cases would probably be severe
infections.
When MERS hit Saudi Arabia, individuals were
getting infected from camels. Many of the hospitalized cases were people with
underlying health conditions, with many mild cases detected only using a test
developed for the virus. The mild infections seem not to transmit to others, he
said, “so they are dead-ends for the virus.”
As a result, MERS tends to cause small,
self-limiting clusters of cases. MERS infections are still happening because
people are still being exposed to infected camels, he said.
In China, authorities have not yet identified
the source of the virus. It is almost certain to be a mammal, because
coronaviruses are mainly mammalian viruses, Rambaut said.
Chinese authorities have closed the wild-animal
market in Wuhan. If that is the source, the outbreak will probably go away, he
said. But the virus will still be out there in the animals somewhere, so it is
important to find the direct source.
Authorities also need to create a fast and
sensitive test that can detect the new virus in clinical samples. “Once you
know what you are looking for, it is much easier to find it,” Rambaut said.
Over the past week, people with symptoms of
pneumonia and reported travel history to Wuhan have been identified at
international airports. The WHO is not recommending any specific measures for
travelers, and is advising against any restriction on travel or trade with
China based on the information available.
China’s transport officials told reporters
Thursday that they will take measures, such as disinfecting transportation
hubs, to prevent the spread of the illness during the Lunar New Year period
later this month, when more than 400 million Chinese are expected to travel.
Sun reported from Washington.
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