En lugar de esperar a que surjan nuevos virus, deberíamos estar buscándolos

Rather than Waiting for New Viruses to Emerge, We Should Be Looking for Them

17.2.2021
GeoffBrooksUnsplash
Photo: Geoff Brooks / Unsplash - Kew Boulevard Yarra River, Melbourne, Australia.

One morning, a 2-year-old boy from a small village in Guinea, where large amounts of the rainforest has been destroyed due to logging and mining activities, sat down to play at the foot of a dead tree full of sleeping bats. A couple of weeks later, he and his family fell sick and died. This is how the worst Ebola outbreak in recent history (30,000 cases and 11,000 deaths) is believed to have started.

What do Ebola, AIDS,West Nile Virus and the new SARS-CoV-2 coronavirus that has caused the worst pandemic in the last 100 years have in common? They are all caused by viruses that jumped (once or more than once) from animals to humans. In fact, 60% of infectious diseases in humans are caused by bacteria, viruses or other pathogens that come from other animals, which is why they are called zoonotic diseases.

What do Ebola, AIDS, West Nile Virus and the new SARS-CoV-2 coronavirus that has caused the worst pandemic in the last 100 years have in common? They are all caused by viruses that jumped (once or more than once) from animals to humans

Although some zoonoses such as the bubonic plague or rabies are quite ancient, the number of zoonotic diseases and the frequency of their outbreaks has increased over the last decades. This is the direct result of human activities- such as deforestation and wildlife trade- that increase the probability of coming into contact with new viruses, as well as factors that favour their spread – such as urbanization and global travel. Three out of four newly described diseases in humans have a zoonotic origin.

COVID-19 is the latest of a string of zoonotic diseases that have emerged in the last few decades. All evidence to date indicates that the virus emerged from a family of SARS-like coronaviruses that infect bats, although precise information on how, where and when this jump from animal to human occurred is sorely missing (a WHO-led mission in China is currently trying to investigate this).

At some moment towards the end of 2019, a bat-related coronavirus acquired the capacity to infect humans and to spread from person to person. Whether passage through an intermediary animal host was necessary or not is still a matter of debate

In any case, at some moment towards the end of 2019, a bat-related coronavirus acquired the capacity to infect humans and to spread from person to person. Whether passage through an intermediary animal host was necessary or not is still a matter of debate, but pangolins could be involved, given the high homology between a pangolin coronavirus and the SARS-CoV-2 domain that binds to the human ACE2 receptor, as well as the extensive trade of pangolins in China’s wet markets.

Understanding how the COVID-19 pandemic started will certainly help to avoid outbreaks caused by other coronaviruses (say, a COVID-25 or a COVID-40) in the future. However, regardless of if and when we manage to have this information, we do know there are a number of things we should be doing to reduce the risk of another pandemic of this magnitude.

 

PHOTO: Pangolin in Namibia. Alex Strachan / Pixabay.

Seek, don’t wait

There are 320,000 unknown viruses in mammals alone, according to one study’s estimates, or 40,000 according to another study (which is still a lot, considering we only know 1,200 human pathogens, including bacteria, viruses and fungi). For years, scientists have been warning of the pandemic potential of zoonotic pathogens, known or unknown. The World Health Organisation even gave it a name (disease X), acknowledging the probability that the next pandemic would be caused by an unknown pathogen. They were right.

Rather than waiting for new viruses to emerge, we should be looking for them. The USAID-funded PREDICT project was launched in 2009 in response to the 2005 H5N1 avian flu scare and became the world’s largest project aimed at finding new pathogens. In collaboration with laboratories in different countries, including one in Wuhan, China, scientists visited hospitals to identify people with diseases of unknown origin and sampled animals in farms and markets as well as people in daily contact with these animals. This is what is called a One Health approach.

The cost of discovering the planet’s potentially dangerous zoonotic viruses would be between 1.5 and 6 billion USD, which is literally peanuts compared to the estimated cost of the current pandemic (16 trillion USD)

Scientists working in the project detected 1,200 viruses with potential to infect humans- 160 of them were coronaviruses. Ironically, funding for PREDICT ended just when the COVID-19 pandemic was beginning. Although the project did not predict or avoid the current pandemic, it did help build the necessary capacities to battle it in many of the participating countries. It also set the bases for the Global Virome Project, a 10-year collaborative initiative launched in 2018 and aimed at developing a global atlas of the planet’s potentially dangerous zoonotic viruses. This surveillance could be supported by a Global Immunological Observatory (which would collect and analyse blood samples in zoonotic hotspots).

The cost of discovering these viruses would be between 1.5 and 6 billion USD, which is literally peanuts compared to the estimated cost of the current pandemic (16 trillion USD).

 

Photo: Deforestation in Nan Province, Thailand . Boudewijn Huysmans / Unsplash.

Prepare, prepare and prepare

At some point, this is going to happen again. And it could be worse. Next time it could involve a deadlier or even more transmissible virus. We must be ready. Science-wise, it means developing wide-spectrum diagnostic tools, antiviral drugs, and easy-to-design vaccine platforms (mRNA vaccines, successfully used for the first time in this pandemic, hold great promise for responding quickly to future pathogens). This is something that CEPI (the Coalition for Epidemic Preparedness Innovations, founded in 2017) has greatly contributed to.

Countries (and especially Western countries, as this pandemic has revealed) also need to reinforce public health fundamentals such as testing, contact tracing, isolating and communicating in a clear and timely manner with the public. Preparedness also involves establishing the necessary frameworks at the political and global governance levels to facilitate international scientific cooperation, ensure political will to share data, and solve ethical issues that may arise. Preparedness is not glorious- it takes time and hard work, and is rarely appreciated until things go wrong. But this pandemic has hopefully helped convinced politicians of the need to prepare in times of peace, and to invest the necessary resources (financial and human) for the long-run.

At some point, this is going to happen again. And it could be worse. Next time it could involve a deadlier or even more transmissible virus. We need to get ready science-wise

Eliminating zoonoses is impossible – we live closely connected with other living beings, including microorganisms. We cannot prevent viruses from mutating and jumping from one species to the other. And this is why we need to better survey and better prepare. But we can also considerably reduce the risk of dangerous viruses jumping into humans in the first place. Banning wildlife trade would be a great way to start.

Recommended reading:

How Humanity Unleashed a Flood of New Diseases. New York Times. June 2020.