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5 February, 2020 10:40:29 AM

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The novel coronavirus: How worried should we be?

Outbreaks of new viruses, such as the Wuhan coronavirus, are a constant reminder of the need to invest in research in emerging virus biology and evolution
Mohammed Abul Kalam, PhD
The novel coronavirus: How worried should we be?

The death toll from a newly-discovered coronavirus in China has crossed 400. What is a coronavirus? The name of coronavirus comes from its shape, which resembles a crown or solar corona when imaged using an electron microscope. The electron microscopic image reveals the crown shape structural details for which the coronavirus was named. This image is of the Middle East respiratory syndrome coronavirus (MERS-CoV). Coronavirus is transmitted through the air and primarily infects the upper respiratory and gastrointestinal tract of mammals and birds. Though most of the members of the coronavirus family only cause mild flu-like symptoms during infection, SARS-CoV and MERS-CoV can infect both upper and lower airways and cause severe respiratory illness and other complications in humans. This new 2019-nCoV causes similar symptoms to SARS-CoV and MERS-CoV. People infected with these coronaviruses suffer a severe inflammatory response.

Unfortunately, there are no approved vaccines or antiviral treatment available for coronavirus infection. A better understanding of the life cycle of 2019-nCoV, including the source of the virus, how it is transmitted and how it replicates are needed to both prevent and treat the disease.

Origins in Wuhan: We first heard about cases of pneumonia caused by a new virus in December from authorities in Wuhan, China – a city of 11 million people.

What started as a cluster of 27 people with pneumonia – with common symptoms including fever, dry cough, chest tightness and difficulty breathing – has spiraled to 582 confirmed cases, including medical staff, and 17 deaths? The cases span 13 provinces in mainland China as well as Thailand, Japan, South Korea, the United States, Taiwan, and Macau.

In December 2019, a cluster of pneumonia cases was reported in Wuhan, eastern China. The pneumonia is associated with a previously unidentified coronavirus related to the deadly SARS virus.

The virus has now spread to other cities in China, including Beijing, Shanghai, and Guangdong. There have also been confirmed individual cases in other countries, including Thailand, Japan, and South Korea.

The World Health Organization has urged countries around the world to enhance their surveillance of severe acute respiratory infections, although no travel restrictions have been advised. There is no licensed vaccine or specific treatments for the new virus.

The new coronavirus outbreak is linked to a market in Wuhan, which sold meat and lives animals. Following the outbreak, the market was closed. There is no clear evidence of the virus spreading between humans, and it is thought that it originated in animals.

Scientists investigating the outbreak – including those from China – have reported complete virus genome sequences found in patients. The virus is not closely related to any human virus currently in circulation.

SARS-CoV was traced to several animals, including civet cats and raccoon dogs, being sold as food in markets. The infected animals had no symptoms. Closure of the markets with animal culling alongside treatment and containment of patients led to the outbreak being halted.

Further investigations treated SARS-like viruses to horseshoes bats found in a cave in China. It is thought that civet cats could have picked up the infection from bats and then spread it to humans in city markets.

SARS has not been seen since 2003 and it is thought that the virus is now extinct. The new Wuhan coronavirus is not the SARS-CoV, but it is similar to viruses thought to be precursors of SARS in bats.

Coronaviruses frequent species jumps: Coronaviruses are so named because of the crown-like appearance of their virus particles when seen under an electron microscope (corona, meaning crown). Coronaviruses are a diverse group of viruses that infect and cause disease in humans and other animals, including pigs and chickens.

There are seven coronaviruses known to infect people, including the novel Wuhan coronavirus and SARS-CoV already mentioned. Other human coronaviruses are those that cause the common cold like 229E, NL63, OC43, and HKU1 viruses, as well as the deadly zoonotic MERS virus.

Coronaviruses appear to jump easily between species, and the Wuhan virus could be the third incidence in humans in the last 20 years. In 2016, another coronavirus was responsible for 24,000 pigs’ deaths in southern China. Later named swine acute diarrhea syndrome or SADS-CoV, it jumped from bats to pigs but did not spread to humans before it was contained.

Looking further back, close animal counterparts have been found for three of the common cold coronaviruses, suggesting zoonotic origins. Also, for SARS and MERS-CoVs it appears that an intermediate host was needed – either civet cats or camels, respectively – for this jump to be successful. The reasons why aren’t exactly clear.

Virus hunting and mass genome sequencing efforts across the world have associated much of the known coronavirus diversity to bat species. Many of these CoV-infected bats are found in south-east Asia, but other hotspots include South America, Central Europe, and Africa.

What we still need to know: How the new Wuhan coronavirus came to be in humans, and how closely it will resemble the SARS outbreak, will be a focus of ongoing research, such as (1) Sequencing more virus strains to better understand their diversity and evolution. This will allow scientists to develop much-needed tests and track virus spread, assessing whether human-to-human transmission is occurring,

(2) Provide robust evidence that the new coronavirus is associated with pneumonia either through detailed clinical investigation or experimental assessment of causation in a lab animal, and (3) find the origin of the outbreak, determining the role of bats and intermediate animal hosts in the spread of infection.

Outbreaks of new viruses, such as the Wuhan coronavirus, are a constant reminder of the need to invest in research in emerging virus biology and evolution, how they infect and interact with human cells, and ultimately, to identify safe and effective drugs to treat – or vaccines to prevent – serious disease.

This is all occurring during peak influenza season in China so there are some illnesses around that may appear similar to coronavirus. It’s also a time when millions of people in the region travel home to family for Lunar New Year celebrations, potentially carrying the virus to new places, as we’ve already seen.

Development of a diagnostic test: China was extraordinarily efficient and open in identifying the virus, a new strain of coronavirus, within just over a week. Chinese scientists sequenced the virus’s genetic code and, within days, shared that information with the world.

This allowed researchers from Germany to rapidly develop and openly share a suite of specific nucleic acid tests that sensitively identify the virus by detecting small amounts of its ribonucleic acid (or RNA, similar to DNA). Researchers in Hong Kong and from the Chinese Centre for Disease Control then published their own different tests.

How does it spread?We don’t know where the new virus came from originally. We think it originated in animals, but testing so far has not confirmed a specific animal host. Analysis of the genome suggests it has only recently emerged in humans. So which host were humans exposed to? And how was it transmitted to humans?

Transmission: The first case of 2019-nCov came from Huanan Seafood Market in Wuhan. On December 31, China reported 27 people had suffered from symptoms of pneumonia such as fever and difficulty breathing, and there were signs of abnormal infiltration in the patients’ lungs. The Chinese government closed the market to prevent the spread of the disease. Novel coronavirus (nCoV) is a virus from the coronavirus family. It’s a close relative to MERS-CoV and SARS.

 Common medical symptoms of coronavirus infection are fever and difficulty breathing. In severe cases, the infection can lead to pneumonia, SARS, kidney failure and even death.

This is not the first time in the last decade that a virus from an animal was reported to infect humans.

Prevention: There is currently no vaccine available to prevent transmission. But we still can do things to prevent the disease from spreading.The most important thing we can do for prevention is washing our hands with soap. Cleaning your hands is easy and cheap. A number of disease transmissions are through hands. So, keeping our hands clean is crucial.When you cough and sneeze, cover your nose and mouth with a tissue or with your arm (not with your palm).Use a mouth and nose mask when you are sick or in a public space. Dispose of the used tissue and mask in the trash and wash your hands.Avoid contact with farm and wild animals. Cook meat and eggs thoroughly.

If you plan to visit a country where this virus is found such as China, Thailand, and Japan, be careful and take care of your health. If you experience symptoms similar to those above after going to these countries, don’t panic – go immediately to the hospital and report your conditions.

Some evidence suggests it can also spread between people. We don’t yet know-how, but we can make some guesses. It seems to be a respiratory virus, given the disease primarily involves the lungs, so it’s likely to spread through the same routes as colds and flu: sneezes and coughs propelling droplets into the air or onto hands that then touch other surfaces, or by touching our eyes, nose or mouth after contact with contaminated surfaces.

We also don’t know how easily it spreads. Initially, it seemed to require prolonged and close contact, making it harder to catch in day-to-day life. However, there are more recent indications that it spreads more easily between people.

The writer is Former Head, Department of Medical Sociology, Institute of Epidemiology, Disease Control & Research (IEDCR), Dhaka, Bangladesh

MK

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Published by the Editor on behalf of Independent Publications Limited at Media Printers, 446/H, Tejgaon I/A, Dhaka-1215.
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Editor : M. Shamsur Rahman
Published by the Editor on behalf of Independent Publications Limited at Media Printers, 446/H, Tejgaon I/A, Dhaka-1215.
Editorial, News & Commercial Offices : Beximco Media Complex, 149-150 Tejgaon I/A, Dhaka-1208, Bangladesh. GPO Box No. 934, Dhaka-1000.

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