He doesn't have a name yet, but he's already killed three people. An unknown virus, close to pneumonia, has been spreading in China since December. According to Chinese authorities, more than 220 people have been infected and four cases have been reported outside the country, in Japan, Thailand and South Korea. This Monday, a Chinese expert also confirmed that the disease could be transmitted between humans, which makes doctors fear a spread of greater magnitude.
This disease is caused by a coronavirus that infects the respiratory tract. The first cases were reported in Wuhan, a city of 11 million people in central China. Chinese authorities suspect that humans were infected by going to a city market where wild and domestic animals are found.
From a genetic point of view, it has “80% similarities to SARS” (severe acute respiratory syndrome), explains Arnaud Fontanet, head of the epidemiology unit for emerging diseases at the Pasteur Institute. This is why doctors rely on the characteristics of this virus, whose epidemic killed more than 750 people worldwide in 2003, to understand the epidemic that is looming in China today.
The virus spreads beyond Chinese borders
In 2002, the spread of SARS started with bats: however, "they did not directly transmit the virus to humans," explains Anne Goffard, professor at the University and at the University Hospital of Lille. This mutated by transmitting to another animal, the civet, which the Chinese eat. This is how humans then contracted the disease. In the case of the new virus, doctors have not yet identified which animal is responsible for transmission to humans.
The first cases were detected by the Chinese authorities from December 15. On January 1, they closed the market suspected of being behind the epidemic. Before this weekend, they estimated the number of people infected at around 40. At the start of the week, they revised this figure upwards, referring to more than 200 people.
But for some scientists, this figure is largely underestimated: researchers at Imperial College London have counted more than 1,700 probable cases in Wuhan since January 12, based on statistical projections.
What particularly worries the authorities is that the virus has now crossed the borders of China: two cases have been identified in Thailand, one in Japan and one in South Korea. These four people diagnosed abroad had all stayed in Wuhan.
The risk of human-to-human transmission
However this Monday, Zhong Nanshan, a renowned Chinese scientist of the National Health Commission, confirmed to the state television channel CCTV that the transmission by contagion between people was "proven". In other words, an infected person who is in contact with healthy individuals can transmit the virus to them. And if she travels ...
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This precision does not fail to worry the Chinese and their neighbors, especially since the epidemic comes near the festivities of the Chinese New Year, the busiest period of the year in transport. Hundreds of millions of people have started traveling by bus, train and plane to visit their families. "The speed and the large number of trips favor epidemics," explains Anne Goffard. In 2003, SARS, which appeared in China, had traveled to Canada, for example.
"Our main fear is that the virus will mutate to become more transmissible and more virulent," says Arnaud Fontanet. This would further complicate the task of doctors, who already know little about this virus: the incubation period, for example, is still unknown, even if the authorities assume that it is close to that of SARS (14 days maximum ).
However, Arnaud Fontanet remains optimistic: “The Chinese authorities quickly identified the fact that there was a new virus and shared its genetic sequence with the rest of the world. ”This made it possible to set up a specific test to identify cases, and therefore better manage them if they had to come to France.