Scientists look for the origin of Wuhan's coronavirus in animals

Most experts rule out that they can be snakes and point to mammals.

WHO decides not to declare the international emergency due to the Wuhan coronavirus.

While the World Health Organization (WHO) decides whether to declare the Wuhan coronavirus outbreak an international emergency, after it has claimed 17 victims so far, Chinese authorities have decreed quarantine in three cities and asked 20 million citizens not to leave their cities except for "special reasons" in an attempt to contain the virus.

Other security measures have also been implemented, such as the closure of public transport and controls at airports.

The source of the infection is suspected to be a food market in Wuhan, a mega-city of 11 million people located in central China. 

The market was closed on 1 January and disinfection measures were implemented, making it difficult to trace the origin of the infection, i.e. which animal caused the infection. 

Dead and live animals, wild and domestic, including marmots, birds, bats and snakes, were sold on this market.

A team of researchers from Peking University in China has surprised the scientific community by pointing out that the Wuhan coronavirus could have been transmitted from snakes. 

To make that claim, they compared the genome of five samples of the new virus with 217 similar viruses obtained from other special animals. 

According to the authors, the new virus is genetically similar to that found in bats - which are the natural reservoirs of other coronavirus viruses, such as SARS - but is more similar to that found in snakes.

However, that announcement has quickly encountered criticism from most international experts. 

"At the moment, it is very risky to say what animal the infection comes from and also to know if it was already circulating, before the cases of pneumonia were detected in December in Wuhan," says Jose Muñoz, head of the international health service in the Hospital Clínic de Barcelona and researcher of the Institute of Global Health of Barcelona (ISGlobal), center driven by 'la Caixa'.

In the Center for Research in Animal Health (CReSA) of the Institute of Research and Agrifood Technology (IRTA) they have been working for years in the field of coronaviruses, especially with the MERS-CoV type. 

Already in 2016 they tested a vaccine for dromedaries, the natural reservoir of this type of coronavirus, to see if it could effectively prevent infection.

"No evidence has been found so far that points to snakes as the origin a researcher at this center explains. Coronaviruses can be found in many animal species, but each type of coronavirus is very specific to certain species. 

It's one thing for them to jump from one mammal to another, but it's quite different for them to pass from a reptile to a mammal, the researchers say.

In this sense, the researchers from the IRTA animal health programme explain that just this morning they carried out an in silico test and studied the probabilities of the corona virus coming from snakes "and the probability was very low".

Moreover, recalls the researchers, in previous epidemics caused by coronaviruses similar to Wuhan's, such as SARS and MERS, the reservoir has been mammalian. 

There is no precedent for a reservoir in reptiles with coronaviruses. 

In this regard, during the meeting held yesterday by the WHO as an emergency with experts in epidemiology and virology, it was stated that at the moment it is not known with certainty which animal has caused the infection.

The study of the Wuhan virus has shown that it has receptors that are compatible with chickens and civets (a type of wild cat), just like SARS," says the study's author, who emphasizes that "this is a very initial prediction that must be confirmed with future epidemiological and experimental studies."

How does the corona-virus jump among animal species?

The new coronavirus 2019-nCov belongs to the same family as SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome). 

They are, explained by CReSA-IRTA, zoonotic diseases, that is, they are transmitted from animals to humans. 

Although they also have the capacity to be transmitted between humans. 

This is possible because the virus acquires a series of genetic mutations that allow it to infect humans and replicate in their cells.

These viruses have the capacity to mutate and by natural selection, a totally random process, they can make mutations that allow them to adapt to humans and other animals.

Previous studies have revealed that the origin of SARS and MERS is found in bats, and the civet, a wild cat found only in Asia and Africa, and camels, respectively, have acted as a bridge between bats and humans.

Which population is at risk for the disease?

Most coronaviruses cause cold-like symptoms, but both SARS and MERS affect the airways, especially the lungs, and cause symptoms similar to those of double pneumonia. 

So does the new 2019-nCov. 

In some cases, it can lead to death. At the time of writing, 17 people had already died from this virus.

The population most at risk, both in SARS and MERS and probably also in this new virus, with males and people with collateral diseases, such as advanced diabetes or cancer, or older people, all three viruses cause a picture similar to bilateral pneumonia. 

In the case of SARS, mortality was lower, 10%, compared to MERS, 25.30%. And in this new virus, it is between 2 and 4%, so for the moment it does not seem as serious as the others," he adds.

Are there vaccines or treatments?

Since the first cases of pneumonia appeared in the city of Wuhan in December, research centers worldwide have managed to identify different genetic sequences of the new coronavirus and have confirmed that it has 70% similarity to SARS.

Efforts are also being made to isolate the virus. 

In this way we could begin to know better and develop potential vaccines or treatments, as well as develop specific diagnostic tests.