AIDS in Ethiopia, viral hepatitis in Egypt, acute encephalitis in children in Vietnam, microcephaly linked to the Zika virus ... Tracking infectious diseases is his job. Arnaud Fontanet, head of the epidemiology unit for emerging diseases at the Pasteur Institute, explains the great hunt underway to stop the spread of the Chinese coronavirus, from the same family as SARS which had killed 774 people worldwide between 2002 and 2003. This Wednesday, the death toll reported 17 dead.
How do virologists and epidemiologists work in an epidemic like that of the Chinese coronavirus?
ARNAUD FONTANET. The urgency was first of all to develop a diagnostic tool. It's done and it's effective. At one time, we suspected a first case in France. This screening test made it possible to exclude the presence of nCOV in this person returning from Wuhan.
But this virus, which can degenerate into fatal pneumonia, was a complete stranger until then. How did you do it?
In 2002, the Chinese authorities had for several months minimized the epidemic, which had complicated our work. There, they did not put the case under the carpet. From January 10, less than a month after its start, they identified the virus and made its genetic sequence available on a basis accessible to all researchers. This allowed us to draw up his identity card and to develop this test.
To date, sequencing confirms that it is indeed the Wuhan fish market that started the epidemic. But do we know the identity of the zero patient?
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No. We do not know who he is, as well as his profession, if he is for example a merchant, a cook, as suggested by the fact that the epidemic began in an animal market. Perhaps our Chinese colleagues know this, but for the moment we do not have this information.
Why is this zero patient profiling important?
Depending on his profession, his lifestyle, the contacts he had, we will be able to go back to the source animal, the one that transmitted the pathogen to him.
As for Sras?
Yes. It turned out that Patient Zero was a businessman who supplied fish restaurants in the Canton area. In a market, he was in contact with a small mammal, a civet, which transmitted the virus to him. This animal served as an intermediate host for this coronavirus. In June 2003, the Chinese authorities finally prohibited its breeding and consumption, which stopped the contagion.
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How did we discover that it was the civet, a kind of musk cat, the culprit?
By going to collect field samples of animal stool and urine at Canton markets. This is what we did at the time two of my colleagues from Hong Kong. Virology, in many ways, is like a police investigation.
This field work, who is currently leading it?
Chinese scientists, but we have very little information about what has been done. All we know is that the market in Wuhan has been closed to the public since January 1.
Why, as in Sras, do we find a market at the origin of this new epidemic?
In China, the markets have a particularity, one very often sells live animals there, including wild. This ensures the quality of the animal and its freshness. You can really find everything there: poultry, snakes, frogs, scorpions, owls, turtles, badgers, etc. Coronaviruses are the source of viruses hosted by their animals.
Beyond greater transparency on the part of China than in 2002, what are the reasons not to worry too much?
For the moment, we have not identified what is called in epidemiology “super-contaminants”, in other words patients who have, without their knowledge, contaminated dozens of other people, as happened in 2003 in a hotel and hospitals in Hong Kong. This is rather encouraging. In addition, for the moment, the virus seems less virulent than SARS. But will it mutate to become it, that is the whole question.
