A new pandemic is on the way, whether it starts next week, next year, or within the next decade. Researchers cannot predict exactly when or how an epidemic will start. Approximately 1.6 million viruses It is estimated to be present in mammalian and bird wildlife around the world, and up to half of them can infect humans.countless numbers That’s exactly what I’m trying to do, and at this very moment we’re running into people who are hunting, eating, and trespassing on those creatures. (And that’s just a virus. Parasites, fungi, and bacteria also represent a major infection risk.) The only certainty in predicting a pandemic is that the next threat will arrive sooner than anyone would like.
But scientists can at least make educated guesses. what It may be the catalyst for the next big one. His three main families of viruses are influenza viruses, coronaviruses, and paramyxoviruses, which are more numerous than most other families and in order of increasing threat. Together, these groups make up the “respiratory death triad,” said Sarah Cherry, a virologist at the University of Pennsylvania.
Influenza and coronavirus have been causing problems recently. Since 1918, the influenza virus has caused four pandemics and continues to plague us season after season. Some scientists now fear that another large-scale anthropogenic outbreak is occurring. multiple H5 influenza viruses continue to spread from birds to mammals. The past two decades have also seen three major coronavirus outbreaks with high mortality rates. The first SARS outbreak began in late 2002. MERS probably spread from camels to humans in 2012. And the pandemic pathogen SARS-CoV-2 that has been plaguing us since the end of 2019. Coronaviruses, which cause the common cold, are still a part of everyday life, perhaps a remnant of the ancient animal-to-human spillover that we continued to infect. between us.
Paramyxoviruses, on the other hand, are mostly “smoldering in the background,” says Raina Plowright, a disease ecologist at Cornell University. While influenza viruses and coronaviruses have already been clearly “proven” to be a Tier 1 outbreak risk, paramyxoviruses have not yet been identified as causing a genuine pandemic. But they seem ready to do so and have probably accomplished the feat in the past.Like influenza viruses and coronaviruses, paramyxoviruses can be transmitted through the air, and in some cases very rapidly.That was certainly the case. measlesParamyxoviruses are “literally the most transmissible human virus on the planet,” said Paul Dupleix, a virologist at the University of Pittsburgh. And like influenza viruses and coronaviruses, paramyxoviruses are present in a wide range of animals. more have been discovered Everywhere researchers look. Consider canine distemper virus. This virus, yes, has been found not only in dogs, but also in raccoons, skunks, ferrets, otters, badgers, tigers, and seals. Paramyxoviruses, like influenza viruses and coronaviruses, have repeatedly shown the following possibilities: play hopscotch from those wild animals to us. Since 1994, hendra virus It caused multiple deadly outbreaks in horses, killing four humans along the way. The closely related Nipah virus has been around since 1998. spread repeatedly between pigs and humansthe case fatality rate can rise to more than 50 percent.
The human version of the past few outbreaks has subsided. However, this is not necessarily the case with Nipah virus and other paramyxoviruses that have not yet emerged. Mr Plowright said there was a good chance the world would soon encounter a new highly contagious paramyxovirus. and Super-lethal — an “absolutely catastrophic” scenario that could dwarf the death toll of any infectious disease in recent memory, she said. (New coronavirus infection, a disease with an extremely high mortality rate, has been reported in the past four years) good Under the nipa, An estimated 7 million people were killed. )
But that being said, paramyxoviruses are a #3 candidate for several good reasons. Whereas influenza viruses and coronaviruses change shape rapidly, frequently tweaking their genomes and exchanging genetic material with other viruses of the same species, paramyxoviruses have historically been able to change shape. I was a little more reluctant. “It’s going to bring their levels down,” said Daniel Anderson, a virologist at the Doherty Institute in Melbourne. First, the slow movement of these viruses can make it very difficult for them to acquire properties that promote infection or quickly adapt to spread among new hosts.For example, Nipah virus can spread among people Via droplets from close contact. But even though they’ve had many opportunities to do so, “they’re still not very good at transmitting between humans,” Patricia Thibault, a biologist at the University of Saskatchewan who has studied paramyxoviruses for years, told me. Told.
The genetic stability of paramyxoviruses also facilitates vaccination. Influenza and coronavirus vaccinations must be updated regularly to keep our immune systems in line with virus evolution. But we’ve been using essentially the same measles vaccine for more than half a century, and immunity to the virus appears to last for decades, Dupleix said. Strong and durable vaccines are one of the main reasons some countries have succeeded. eradicate measles—And why the paramyxovirus called rinderpest, which once wreaked havoc on cattle, became one of the only infectious diseases humans have ever experienced. successfully eradicated. In both cases, the poor ability of paramyxoviruses to infect large numbers of different animals helped. Measles is almost exclusive to us. Rinderpest primarily affects affected cattle and their relatives. On the other hand, most influenza viruses and SARS-CoV-2 can spread widely in the animal kingdom. “I don’t know how to eradicate it,” Anderson told me.
But the problem with all these trends is that they only represent what researchers know about the paramyxoviruses they’ve studied—which, inevitably, is only a small subset of what exists. , says Ben-Hur Lee, a virologist at Icahn College at Mount Sinai. medicine. “The demons we don’t know about are just as scary, if not more so,” Lee told me. Paramyxoviruses that don’t follow patterns may already be preparing to pounce.
Researchers are keeping an eye on these looming threats. The World Health Organization highlights Nipah virus and its relatives as follows: Some of the top priority pathogens; In the United States, paramyxoviruses were recently placed on the National Institute of Allergy and Infectious Diseases list of pathogens. Essential for studying pandemic preparedness. Last year, the Bill & Melinda Gates Foundation Funding paramyxovirus antiviral drugs. Several new paramyxovirus vaccines, many of which target Nipah virus and its relatives, may be available soon.
But at the same time, experts told me, paramyxoviruses remain neglected, at least compared to the serious danger they pose. “Influenza has been fatally sequenced,” Lee said. (This is now largely true of SARS-CoV-2 as well.) Paramyxoviruses, on the other hand, are not routinely monitored. The development of treatments and vaccines for them has also received little attention, especially outside of Nipah and her relatives.And while this family has haunted us for generations, researchers Still do not know Find out exactly how paramyxoviruses transfer to new species, or what mutations they need to become more transmissible among us. It is unknown why some paramyxoviruses cause only mild respiratory infections, while others rampage through the host until it dies.
Even the vaguely familiar paramyxoviruses surprise us. In recent years, scientists have discovered that immunity to paramyxovirus mumps, once thought to be very long-lasting and strong, waste away in the first decades After vaccination; versions of the virus that were once thought to be only a problem for humans and a few other primates also detected in bats. For these and other reasons, rubella virusThe paramyxovirus subfamily, which includes mumps, is one of the potential pandemic pathogens of greatest concern to Duprex. Emmy de Wit, head of the Molecular Etiology Unit at Rocky Mountain Research Institute, said the world could become more vulnerable to the Morbilliviridae subfamily, which includes measles. If measles is eradicated, some regulatory authorities may seek to phase out measles vaccination. But just as the end of smallpox vaccination left the world vulnerable to measles, waning measles immunity could leave room for closer relatives to emerge.
The next pandemic will not necessarily be a paramyxovirus, or even an influenza virus or a coronavirus.But it’s very likely that it starts like this There are so many other known pandemics out there.—There are ripple effects from animals in parts of the world where we have invaded wild habitats. We may never be able to predict which pathogens or organisms will be involved in the next outbreak, but the common denominator will always be us.
