Where could the next killer epidemic come from? There are even viruses circulating in the world that we better not know about

Viruses have always been able to pass from animals to humans

Several serious epidemics have recently been unleashed as a result of animal viruses “jumping” on humans. Just to name a few, it was Ebola and Zika, for example. Covid may also fall into this category, at least on the basis that a coronavirus very similar to SARS-CoV-2 has been found in bats, suggesting that perhaps the coronavirus epidemic originated in them.

We have known for a long time in history that viruses can pass from an animal to a human being and this happens sometimes. But the geographic region from which they come is less clear, although it would be particularly important from an epidemiological point of view. Knowing where they appear could help to understand the factors that drive the spread of viruses between species, since it would be possible to examine the characteristics of viruses in the ecosystem where the “jump from animal to human” occurred.

But it is often difficult to identify the geographic origin of a virus.

People are constantly on the move, and thanks to rapid transportation, the first case, patient zero, may be hundreds or even thousands of miles from where the “jump” took place.

Looking ahead, therefore, the big question is, where do we have to look for the virus that will cause the next epidemic?

Where to look for the origin of the next epidemic?

In general, new viruses appear when humans and virus-bearing animals interbreed on a regular basis. Repeated interactions between humans, animals and even insects, as well as the greater extent that viruses circulate, increase the chances of a jump between species. Scientists assume that these jumps are quite rare and occur under special conditions that cannot necessarily be predicted.

People are constantly exposed to viruses, but viruses often cause infections that end in a “dead end” when the virus is not transmitted to infected people. However, in some cases, the virus can multiply and find a new host, or if a vector (a living organism carrying an infectious agent that carries it, such as an insect or a domestic animal) It is a virus that is transmitted, you are in a living organism, such as an insect, in which you can create a new cycle of transmission.

This can happen anywhere in the world, but recent outbreaks have suggested that viruses come more often from some geographic regions than elsewhere.

Also, if we look at the fact that serious diseases like SARS come from Asia and Ebola from Africa, we could guess that all epidemics come from these regions. But this is not the case.

For example, the Schmallenberg virus has emerged in Europe, which mainly attacks farm animals and causes spontaneous abortions in infected people. We rarely hear about viruses from South America, but mosquito-borne encephalitis in Venezuela, mosquitoes (encephalitis) The virus also infects humans and the Mayaro virus. (jungle flu) regularly causes minor epidemics in South and Central America. But since they only occur locally, they are not widely known. Mayaro fever is also rarely heard because it is often misdiagnosed and believed to be dengue or an infection caused by the chikungunya virus, so the actual number of cases cannot be really known.

This also raises another question about the birth and spread of new viruses, namely that there are many viruses that cause very similar symptoms at first. For example, in regions where malaria and dengue are considered local diseases, most viral diseases are attributed to these infections, hiding the emergence of new viruses until they spread more widely beyond their place of origin. origin.

Detecting the origin of viruses is made even more difficult by the fact that people who are actually close to the virus do not always show signs of infection, and even if they are regularly exposed to the virus, they may not even produce symptoms.

Therefore, the discovery of a new virus can only occur if the virus enters a community that has not found it so far and where there will be a sufficient number of cases to be detected.

Since today you can go practically anywhere (of course, when there are no restrictions due to an epidemic) this may be in the other half of the world.

In light of all this, the location of the next outbreak cannot really be predicted simply by examining the maps. But then what is the solution? A better way is to try to understand the transmission cycle of the virus, that is, to study animals and their environment where viruses multiply without causing human disease. So the same should be investigated in reverse.

Knowing that viruses are already present in animals can help you understand the origins of human diseases when a new epidemic breaks out. With this, we can understand the risk factors of different regions and help decipher which factors make a virus more likely to attack humans.

Why bats?

For example, by studying the transmission cycles of coronaviruses found in bats, researchers have concluded that an outbreak of SARS-CoV-2 may be associated with bats. And in light of this, we can rightly wonder what is in bats, which is why they so often play a role in transmitting viruses to humans.

One explanation may be that bats adapt to coronaviruses in a way that increases the potential for transmission to mammals such as humans. Another explanation may be that the physiology of bats makes them excellent carriers of viruses. But recent research shows that bats are so frequently used by bats as distributors because many species of bats live, and not bats themselves are exceptionally good hosts.

Understanding the viruses found in bats and other species is just the beginning. In China, research on the origin of the SARS-CoV-2 virus in bats was recently suspended.

However, if we want to predict what the next dangerous virus might be and where it might come from, these investigations should be sped up rather than completed.

Naomi Forrester-Soto, a researcher at Keele University, notes.

(World Economic Forum)

Top image: Equine encephalitis virus, source: Getty Images