health & science

China’s new virus: What you need to know

A new virus which emerged in China in December has killed two people and infected 62 - with fears it could spread from human to human

What started as a cluster of pneumonia cases reported on the last day of the decade has has been identified as a brand new and deadly virus. Originating in Wuhan, China, there are fears this could be a repeat of the SARS pandemic in 2002 which killed 774 people.

Yesterday there was a spike of 17 new cases reported in China, with some said to be in a serious condition. Of all people confirmed to have fallen ill since December two have died, eight are in a serious condition and 19 have been treated and discharged from hospital.

Worryingly, some of the new cases are said not to be linked to the seafood market at which the first cases had originated and which has been closed for some days. The chance the virus is being transmitted between people has not been confirmed but officials say it can't be ruled out. Wuhan, the epicentre of the outbreak, has 11 million inhabitants and is a transport hub. With Chinese New Year days away, if human-to-human transmission is occurring, then there's a risk the virus could infect many more people.

What is it?
The virus is what’s known as a coronavirus. These are a diverse group of viruses which can affect humans as well as animals such as pigs or chickens. Most coronaviruses which affect humans cause mild to moderate illness - like the common cold. More recently SARS (Severe acute respiratory syndrome) and MERS (Middle East Respiratory Syndrome) caused severe illness and death. 

Around 10 percent of people diagnosed with SARS and 36 percent or people diagnosed with MERS died. SARS has not been reported since 2004 and is thought to be extinct. MERS, which emerged in 2012,  is still circulating.

What’s been found in Wuhan is a new coronavirus and is the third in the past 20 years which made the jump from animals to humans. 

How severe is it?
There have been two reported deaths, with one of the dead said to have pre-existing conditions. Symptoms reported include a fever and difficulty breathing. Chest radiographs have shown invasive lesions in lungs. Some people who caught the disease have recovered and been discharged from hospital.

As it’s a viral disease, antibiotics are ineffective as a treatment. Only the symptoms can be treated. There is no vaccine. 

How do you catch it?
Scientists are still trying to figure this out. The virus appears to be closely linked to a seafood market which also sold rabbits and birds. Coronaviruses sometimes jump from bats to another animal. This animal might not get sick itself, but can be infectious to humans.  For SARS, civet cats were the link to humans through meat. In MERS, camels were the go-betweens, with people who handled camels falling ill. Viral spread from seafood to humans is unlikely. 

Is it isolated to one seafood market?
It’s not necessarily just the Huanan Seafood Market in Wuhan involved in the spread. A woman who returned to Thailand from China had the virus. She had not visited the seafood market but had visited another fresh market in Wuhan regularly.

Another visitor to Wuhan returned to Japan carrying the virus. He had not visited the seafood market but had been in contact with somebody suffering pneumonia. A third person with the virus has been detected in Thailand, but details have not been released on whether that person had been to the seafood market.

The market has been shut down and is being disinfected. 

Can humans spread it?
Initially it appeared the virus seemed to be mainly spread from animal to human. However one woman in China whose husband works in the seafood markets has been infected even though she did not visit the market herself. A man in Japan was also diagnosed with it after being in contact with someone with pneumonia. Officials are not ruling out the chance it could be spread between people.

So far, no health workers have been reported as falling ill, so this could indicate a low risk of human to human spread when basic hygiene precautions are taken. 

If human-to-human spread occurs, containing the virus will be far more difficult. 

University of Otago professor Michael Baker explains transmissibility is one of three main factors used to assess diseases. With SARS, each infected person passed it on to between two and four other people.

“If this number is much above one, then we will see an exponential increase in cases.  A very high number means an explosive epidemic.”

Over 8000 people were infected during the SARS pandemic before it was brought under control. This was done by detecting cases, isolating patients and quarantining people who had been in contact with them.

In Wuhan, over 700 contacts of people who have been infected have been contacted and followed up.

Scientists at the Imperial College, London MRC Centre for Global Infectious Disease Analysis have crunched the numbers based on three travellers being detected with the disease. By their calculations there is a one in 574 chance a person would have flown before seeking medical help. With three people falling into that category they surmise the infected number could be closer to 1723. They say this is worrying but also highlight the calculation could be substantially lower or higher:

"There are many unknowns, meaning the uncertainty range around this estimate goes from 190 cases to over 4000."

What happens during Chinese New Year?
Chinese New Year is described as the world’s largest human migration with many millions of trips made as families gather to celebrate the lunar new year. If the disease is transmissible between humans the many trips made during this period could export the virus beyond the cluster which is currently in Wuhan. 

What can I do?
Some countries have issued travel advice for those planning to visit Wuhan. This includes avoiding animals alive and dead, animal markets, uncooked meat and areas with animal droppings. 

Standard advice about hygiene when sick, or when around unwell people, has been given and several countries are screening people for fever and symptoms as they enter the country.

New Zealand’s Ministry of Health has warned health professionals of the emergence of this disease.

Professor Baker said the World Health Organisation is monitoring the situation. 

“The WHO is currently considering whether international measures are needed to control this outbreak. If that is the case, then they could declare it a Public Health Emergency of International Concern. We are still several steps away from that point.”

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