When asked about the possibility of future pandemics, virologists rarely speak words: Another one is coming. It’s just a matter of when.
It is estimated that about 1.7 million viruses exist in mammals and birds, and almost half of them could possibly follow the deadly pathway of the coronavirus responsible for the spread of COVID-19, which means that it can be transmitted from animal to human. jumps and kicks off another pandemic.
The motivation to help a team of researchers at the University of California at Davis find ways to prevent it. They try to help the world’s scientists determine how dangerous each one can be by arranging and developing the likelihood of them being transferred between species in a form that humans can easily transmit to each other. This poorly understood phenomenon, called ‘viral outbreak’, has a long history of outbreaks, including Ebola, MERS, SARS and HIV, the virus that causes AIDS.
The team has launched a web-based tool aptly named SpillOver. The app evaluates 32 risk factors – such as virus species, host species and country of detection – to generate a waste risk score. “We looked at viruses that are transmissible from animals to humans and those that have just been discovered,” says Zoe Grange, who worked on the project as a postdoctoral ecologist for wildlife diseases at Davis. By indicating the so-called “concerned viruses”, the publicly available database is intended to create a watch list for scientists and policymakers.
Grange and her advisor, Jonna Mazet, an epidemiologist at the UC Davis School of Veterinary Medicine, came up with the idea of a ranking during the beach walk in the spring of 2017. Grange says, ‘We asked,’ Why can’t we? do we compile a credit report for viruses? ‘”
The tool is an attempt to make sense of a surge in reports of new animal virus strains collected as part of the $ 238 million PREDICT project led by the US International Development Agency between 2009 and 2019 is. COVID 19 recognizing the threat posed by wildlife viruses, the program has created a global army of 6,800 virus hunters in 35 countries. Some workers collected blood, saliva, urine, or feces from bats, rodents, and primates, while others analyzed the genetic sequences of the samples.
They discovered nearly 900 new viruses, including 160 coronaviruses and a previously unknown strain of Ebola. They also detected 18 previously known zoonotic viruses, such as Lassa and Marburg, which cause hemorrhagic fever. “We have discovered many viruses. But what does that tell you? ” says Grange, who is now Scotland’s chief protection officer for public health. “Not every virus will cause a pandemic.”
The SpillOver database is set up so that researchers can add their own reports. “We wanted to make a tool that everyone could use. They can add their virus discoveries and make their own rankings, ‘says Mazet.
In a study published this week, researchers led by Grange and her team at UC Davis used data from nearly 75,000 animals, as well as public records of virus detections to rank the distribution potential of 887 wild-type viruses. SARS-CoV-2, which is the virus behind COVID-19, came in second place because it is likely to cause and spread diseases within the human population. Although the data was based on limited reports of the virus in zoos, lions and mink, it has evidence that the rankings worked. The World Health Organization is of the opinion that SARS-CoV-2 is likely to spread directly from humans to a bat or via an intermediary, such as a pangolin. The virus that had the highest ranking was Lassa, which is endemic to the rodent population in West Africa and causes bleeding, killing 1 percent of the victims.
Increasing threat of runoff
Unlike other tools that assess the risk of a limited number of viruses, such as influenza, this database focuses on viruses found in 26 virus families in wildlife. It is a welcome resource for the field because it accelerates the rate of spread, says Raina Plowright, an ecologist for wildlife at Montana State University, who studies disease dynamics between humans and animals.
“What I like is that they think very broadly about the risk factors, especially the stress on the ecosystem where the reservoir host lives and the possible interaction that people have with these hosts,” she says. “We are intruding into the last wild spaces and coming into more contact with wildlife and taking away the most important resources animals need to survive.” When the habitat of animals is restricted, they are forced to search for food in more populated areas. Like humans, when animals are stressed, they are more vulnerable to the disease and spread of viruses – among their species, to other animals and possibly to humans.
What is unknown is how some of these new viruses can infect humans, a complex series in which pathogens enter human cells, multiply and spread throughout the body while evading the immune system. While some viruses, such as the Nipah virus, can be transmitted from bats to humans, other viruses must go through an adaptation process to become contagious.
“A virus usually needs multiple mutations to be transmitted to humans,” says Hector Aguilar-Carreno, a virologist at Cornell University College of Veterinary Medicine who studies viral immunology. ‘It will depend on the virus. In some cases, you may need one or two mutations. But some may need 20 or more to undergo the necessary steps to be transferable or repeated in the host. ‘To further complicate the problem is whether these mutations should occur by a third-party animal, as suggested with SARS-CoV-2. The virus would have changed when it possibly jumped to a pangolin and then again when it jumped to humans.
The value of watchlists
The smoothness of such potential flood events raises the question: what should we do with all this information? According to Mazet, who was chief investigator at PREDICT, the data places high-risk viruses on the radars of policymakers. “We created this tool because we did not just want to scare the world that there are a lot of new viruses and no one knows what to do with them,” she says. “The tool is to create surveillance lists for surveillance with all the data on how people are exposed.”
One possible scenario: Since bat-borne diseases can be transmitted by guano (in which coronavirus RNA is detected), farmers who collect guano for fertilizer may be advised to use personal protective equipment or disinfect guano. “We may need to talk about alternative livelihoods if they are too dangerous or need to find new safe practices,” Mazet says. One result of the PREDICT project was the creation of a book entitled ‘Live Safe with Bats’ – the animal most involved in viral distribution events – which has been translated into 12 languages and at hundreds of public meetings in Africa and Asia. offered.
Bats that like date palm juice
When epidemiologist Emily Gurley worked in Bangladesh in the early 2000s, her team was able to use specific information about the bat transmission of Nipah, a deadly virus without treatment, to help villages reduce their risk. After confusing outbreaks of Nipah, Gurley and her colleagues traced the virus back to fruit bats. (Previously, the virus was transmitted to humans by sick pigs in Malaysia.) In many areas of Bangladesh, fresh date palm juice is considered a delicacy; it appears that bats like to lick the juice stream as it flows into collection pots – and meanwhile have contaminated the stock through urination or defecation.
“From this away career, we have outlined the evidence that it was the predominant transmission route,” says Emily Gurley, who is now an associate scientist at the Johns Hopkins Bloomberg School of Public Health. Their efforts led to a public education campaign “drink safer juice” that advised villagers to install only to keep bats away from the collection pots.
Although the PREDICT program ended in September, Mazet said it was aimed at building countries’ capacity to continue such oversight and engage local communities before the next spread – and possibly the next pandemic. A second initiative focuses on educating a pipeline of health workers in various disciplines at universities in Africa and Southeast Asia to focus on disease prevention and detection. “There are still thousands of viruses to be discovered,” she says.