Wuhan virus feeds fear of SARS-like pandemic

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Two dead, and at least 41 people with suspicious symptoms. Seven of them are still in the hospital in critical condition. This is the result of an outbreak of a new corona virus at a covered fish market in the Chinese city of Wuhan.

After it became clear in December that sellers and visitors to the Huanan Sea Food Market had suffered severe pneumonia, the market was closed and disinfected on 1 January. According to the Chinese health authorities, no new cases have been reported since 3 January. The outbreak seems to be stifled.

But virologists are not reassured internationally. The fear is that the Wuhan virus will prove as dangerous as SARS (Severe Acute Respiratory Syndrome). It was also a new corona virus that broke out in a market in China at the end of 2002. The virus then spread across the world via travelers and infected more than 8,000 people. SARS eventually claimed 813 lives before the epidemic ended. At the time, the Chinese authorities tried to keep the outbreak still during the first months, so that measures could be taken very late to prevent further spread. Substantial criticism from the World Health Organization.

The Chinese response is more open this time. The health service in Wuhan now regularly updates the progress in the investigation into the outbreak, although in Chinese, but with translation sites that is no obstacle. In total, 763 close contacts were found in Wuhan of the 41 people who became infected. The medical observation of more than half of them has since been discontinued because nothing seemed to be wrong; 313 contacts are still being monitored. The investigation has found no related cases so far, reports the health service.

Genetic sequences

More important than those public interim reports, is that the Chinese have now also shared the entire genetic sequence of the new virus. This is essential to be able to develop rapid tests that can be used to detect the virus in people with suspected symptoms and to obtain confirmation that it is indeed the Wuhan virus. On January 10, Australian virologist Edward Holmes of the University of Sydney posted the first sequence on behalf of a Chinese research team led by virologist Yong-Zhen Zhang from Shanghai.

The fact that the hares are now walking differently than in 2002 is also apparent from the rapid identification of a 61-year-old tourist from Wuhan who had contracted the virus in her hometown and had gone on holiday to Thailand despite her starting complaints. Upon arrival at Bangkok airport on January 8, it was noted with a thermal camera that she had a fever. The Thai authorities had only just introduced that extra control on flights from Wuhan. Together with some other travelers from Wuhan who also had a raise, she was placed in quarantine. Because Chinese virologists had posted the genetic sequence of the new virus in an international database, the Thai were able to confirm that the woman was indeed infected with the Wuhan corona virus. The woman is now recovering and returns to China. On January 17, a second diagnosis of the virus was reported in Thailand to a 74-year-old Chinese woman from Wuhan. And earlier this week, a Japanese was also diagnosed with the virus. He was in Wuhan in early January. He has also recovered from his pneumonia.

In the meantime, dozens of reports have come from Hong Kong about people who have been to Wuhan and who have symptoms of disease. To be sure they are kept in quarantine. It is striking that a diagnosis here takes so long, while the diagnosis of the Chinese tourist in Thailand took place within a few days. This may also have to do with the political climate in which the Hong Kong people are opposed to the central government of China. Campaigners are also trying to make sense at the virus panic by saying that the situation is so dangerous that the ban on masks (introduced since the outbreak of the riots in the city) must be lifted.

Whether the outbreak of the new corona virus is limited to a local flare of infections in the fish market in Wuhan or whether it can still grow to SARS-like proportions is uncertain. “Here we have a limited view of what exactly is happening in China,” says virologist Marion Koopmans of the Viroscience department at Erasmus MC in Rotterdam. virus behaves the same as SARS. We still have to take a swing. “

Nonetheless, the genetic information shows that the Wuhan virus of all known coronaviruses is closest to SARS. “That is true,” Koopmans agrees, “but at the same time there are still quite a few differences.” In any case, the World Health Organization has called for alert to virus infections. In the coming weeks, it will be exciting when millions of Chinese go traveling in connection with the start of the Chinese New Year. That could play a role in the rapid spread of a local dormant virus.

Human to human

A bit alarming is that there are weak indications that the new virus can jump from person to person. The wife of a man who worked at the fish market and became ill also got pneumonia. According to Chinese reports, the woman “denies” that she herself has been on the market. Also the Japanese man who fell ill, according to the Japanese health authorities during his visit to Wuhan, has not been to a market with live animals. This implies that he became infected through human contacts.

A human contamination chain in particular can make the virus more dangerous, Koopmans says. “Then it gets the chance to adapt to this new host and it can suddenly become much more contagious.”

That is exactly what happened to the other dangerous corona viruses SARS and MERS (Middle East Respiratory Syndrome). Both viruses have developed their own way of efficiently penetrating human lung cells. This allows them to bind to receptors on the surface of human lung cells, after which they can easily penetrate.

The Huanan Sea Food Market in Wuhan was closed on January 1 after multiple reports of serious pneumonia. A shop owner is discussing with security guards here.

Noel Celis / AFP

But for the time being the situation in Wuhan is most like a spill-over from animals, Koopmans says. In addition to fish and shellfish, other animal products were also traded on the market, including live snakes, pheasants and organ meats from rabbits. The source of SARS was then converted to living civet cats that were traded on the market. MERS comes from dromedaries. These animals probably picked up the virus in turn from bats, which are the natural host of many coronaviruses.

Reservoir

Koopmans suspects that the same scenario has taken place in Wuhan. The source was not fish or shellfish, but a wild bird or mammal that was brought to the market. “The virus was probably first able to multiply through the various living animals on the market,” says Koopmans “From that reservoir, the virus has also infected people on the market.”

The virus was found in samples taken on the market site, but the animal or animals that carried it were not identified. That is frustrating, because it means that there may still be contagious animals in other markets. The 61-year-old tourist in Thailand would not have been on the Huanan Sea Food Market, but they have visited other markets with live animals in Wuhan. She may have been infected there. If so, the infection can spread again from new viruses.

It is quite conceivable that there have always been occasional small outbreaks of hopping viruses around live wild animal markets. But as long as those infections did not spread and the number of victims remained limited, that went unnoticed. With modern genetic techniques, the cause of small outbreaks can also be found quickly, so that they are nevertheless revealed. “That may also be the case in Wuhan,” says Koopmans.

The question is whether something can be done to prevent this kind of potentially dangerous virus outbreaks in the future. “I think that is very difficult,” says Koopmans. “The outbreaks are almost always related to markets on which live animals are traded. After the SARS epidemic in 2003, and the outbreak of H1N1 bird flu among people in 2009, the debate about this has been ongoing. You cannot simply abolish those markets, it is also part of the culture of a country. But of course it is a risk practice. ”

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