This week, the Spanish Ministry of Health confirmed the evidence that experts have suspected since the beginning of the COVID-19 pandemic. Bats are the cause behind the coronavirus outbreak. In other words, scientists are nearly 100% sure that bats are the original reservoir of this illness.
Experts have suggested that bats are the cause of the pandemic right from the start. Bats possess an extremely resistant immune system that’s capable of tolerating high viral loads. What’s more, they’re able to transport a variety of diseases that are lethal for humans. Among these are ebola, rabies, and the SARS virus that first appeared in 2002.
Studies like the one directed by the journal Nature Microbiology, point out that resistance in bats may have to do with their ability to reduce inflammatory responses.
Single-stranded RNA viruses–such as COVID-19–tend to produce exaggerated responses in the immune system, which can lead to complications. Scientists believe that by limiting their inflammatory response, bats can carry a number of illnesses, but barely show any symptoms at all.
Therefore, they’re the mammal order that carries the greatest number of zoonotic viruses (those that spread between species) in the world. So now, what does this discovery imply and what do we need to know in order to understand it? We’ll tell you in the following article.
Hosts and reservoirs
A host is a species that harbors another inside of itself. In general terms, we can distinguish between different types of hosts:
- Primary: The host where a parasite carries out the majority of its existence, growth, and reproduction. The adaptations of the pathogen are specially developed in order to affect this host, and maximize its adaptations and expansion without quickly ending the host’s life.
- Secondary: Hosts the parasite only in the initial phases of its growth and is linked to the expansion and transmission of the pathogen to its primary host. They act as a bridge.
These types of hosts are easily exemplified in the life cycles of complex parasites. The larvae live in an animal, but the animal later expels them into water. Then, the larvae infect another species, where they develop into adulthood.
However, these lines become blurry when it comes to viruses. This is because their life cycles are much simpler and depend greatly on the immune system of the species in question. This is why it’s more correct to speak in terms of reservoirs.
A host reservoir is a primary host that harbors an infectious agent or parasite that can occasionally come to invade the body of humans or another species of economic interest. Therefore, the confirmation that we have on hand is that bats are the cause behind the COVID-19 pandemic. In other words, they were the primary reservoir of the new coronavirus.
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Scientists continue to have the pangolin their sights
We know where the cycle of coronavirus started–bats–and we know where it ended up–human beings. But what happened in the middle?
In order for this illness to have made its way to us, it must have had an intermediate reservoir. This bridge between bats and humans had to have existed since bats and humans rarely come into contact. The pangolin continues to be the main suspect.
The Spanish Department of Health, directed by Salvador Illa, continues to name this likable mammal as the most probably focus of secondary infection. Recently, scientists discovered the sequence of other coronaviruses in 30 samples of pangolin meat. The coronaviruses they detected in this tissue bears a genetic similarity of between 85 and 92 percent with SARS-CoV-2. This data reveals the very possible relationship between COVID-19 and pangolins.
In China, illegal markets sold pangolin meat for human consumption. This placed the first vehicle–bats share the same ecosystem with the pangolin–in indirect contact with human beings. Researchers have yet to explain the direct relationship between the pangolin and COVID-19, but all evidence points to this mammal as the second reservoir.
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What does this discovery mean?
Knowing with near certainty that bats are the cause of the new coronavirus means that the bat is more important than it may have seemed. This information makes it possible to investigate more thoroughly the mammal species that are in close contact with bats. What’s more, it will help to regulate the prohibition policies regarding the consumption of exotic animal meat.
The best strategy in the face of a potential pandemic is to avoid exposure to the virus in the first place. By hardening laws regarding the illegal trafficking of these animals, we avoid exposing ourselves to possible reservoirs of illness we have yet to discover.