These 4 lethal viruses could fuel the next pandemic, new research says. What they areand how the world can prepare – Fortune

Deaths from a handful of viruses that spill over from animals to humans are set to increase 12-fold by 2050 due to climate change and habitat encroachment, according to a new study published in the British Medical Journal.

Three of the fourfiloviruses like Ebola and Marburg, SARS, and Nipah virusare on the World Health Organizations list of priority pathogens, noted for their potential to cause the next pandemic.

But the Ebola-like Machupo virus is also a contender, the authors of the new study argue. And regardless of which pathogen ends up fueling the next global health crisis, theyre all worthy of attention, the authors maintain.

The reason: Epidemics of the viruses they focused on are set to cause a combined death toll of more than 15,000 annually by 2050, even if they dont make an evolutionary leap that allows them to ravage the globe.

Researchers at Boston-based biotech firm Ginkgo Bioworks honed in on four viruses likely to pose a significant public health risk and endanger economic or political stability. Called zoonotic viruses, they spill over from animals to humans, who can then transmit them to other humans.

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Viruses in this family cause hemorrhagic, or bloody, fevers, which are typically accompanied by bleeding from bodily orifices and/or internal organs. The family consists of five strains of Ebola in addition to Marburgan extremely similar virus that made headlines during an outbreak in Equatorial Guinea earlier this year.

On average, Ebola kills about 50% of those it sickens, though case fatality rates have ranged from 25%-90%, according to the WHO. Marburg also kills around 50% of those it infects, though case fatality rates range from around 24% to 88%, experts say. While there are two licensed vaccines for the deadliest strain of Ebola, Zaire, there arent any for the four other strains. Nor is there an approved vaccine for Marburg, though some are in development.

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The worlds first confirmed coronavirus pandemic occurred in 2002, when SARS-CoV-1 was reported in China. It spread to more than two dozen countries in North and South America and Europe before being contained seven months later. It is thought to have originated in an animal population, perhaps bats, before being passed to civet catsa tropical animal that looks like a mix of a dog and an ocelotthen to people. A spillover could happen again.

Symptoms include headache, body aches, mild respiratory symptoms, possible diarrhea, an eventual dry cough, and pneumonia in most. SARS sickened nearly 8,100 people and killed just under 10% of them from 2002 to 2003. There is no licensed vaccine for SARS, though researchers are working on universal coronavirus vaccines that could target both SARS and COVID, among other coronaviruses.

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Nipah is a henipavirus, the most lethal of paramyxoviruses. It was first identified in pigs in Malaysia and Singapore in the late 1980s, though its natural reservoir is fruit bats. The other henipavirus known to infect people, Hendra, was first noted in racehorses and humans in Australia in 1994. Both feature respiratory illness and severe flu-like symptoms, and may progress to encephalitisinflammation of the brainalong with other neurologic symptoms and death.

Nipah kills between 45% and 75% of the people it infects. No licensed vaccines exist, though a vaccine by Moderna, in coordination with the U.S. National Institute of Allergy and Infectious Diseases Vaccine Research Center, is being evaluated.

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Also known as black typhus and Bolivian hemorrhagic fever, Machupo was first isolated in Bolivia in 1959. The Calomys callosus field mouse is a natural carrier of the virus, the symptoms of which are Ebola-like and include bleeding, high fever, pain, and rapid death.

Machupo kills between a quarter and a third of those it infects. Though there are no licensed vaccines for it, a vaccine for Argentinean hemorrhagic fevercaused by the similar Junin virusmay also offer protection against Machupo, according to Stanford University.

Researchers only looked at outbreaks that killed 50 or more people between 1963 and 2019. They didnt take into account the following viruses, which may have otherwise met their criteria:

SARS-CoV-2: The virus behind the recent COVID pandemic may have been caused by a lab leak instead of spillover from an animal like a raccoon dog or pangolin. Thus, its not certain that the virus is zoonotic. Whats more, including this disease could skew the studys numbers, making projected deaths look higher than they potentially should be. Regardless, the COVID pandemic occurred just after the studys 2019 cutoff. COVID is, however, on the WHOs list of priority pathogens.

Hantaviruses and Lassa virus: Both rodent-spread viruses were eliminated from consideration because surveillance has increased over time, potentially causing the growth of studied viruses to appear greater than it should be.

Flu and vector-borne pathogens: Flu viruses like 2009s H1N1 and vector-borne diseases like Crimean-Congo haemorrhagic fever and Zika virus were excludedthe former due to surveillance programs that have grown with time, with the potential to skew predictions on the high end, and the latter due to eradication programs that have the potential to skew predictions on the low end.

When crunching numbers on outbreaks, researchers looked at the number of dead, not the number infected. Thats because the number of fatalities is typically more accurate, given that people can contract a disease and show few or no signs of it.

After epidemics were whittled down, the scientists came up with the following calculus:

The figures are likely an underestimate, the authors cautioned.

Most of the 72 outbreaks they examined were caused by filoviruses in Africa like Marburg and Ebola, which comprised more than half of outbreaks. The duo of viruses caused more than 90% of the 17,000-plus total deaths.

While SARS was the No. 2 leading cause of deaths, at 922, it caused a significantly smaller amount of infections, mainly impacting Asiaas did the Machupo and Nipah viruses, which caused 529 deaths combined, mainly impacting South America and Asia.

The researchers findings suggest that spillover events are not an aberration or random cluster, but follow a multi-decade trend in which [such] epidemics have become both larger and more frequent, the authors wrote, adding that urgent action is needed.

One of the most important things we can continue to do is early detection and intervention, which has been shown time and time again through research to be one of the most effective ways to limit the start of an outbreak, Amanda Meadows, a data scientist at Ginkgo and lead author of the paper, told Fortune.

During the pandemic, collective gains were made in wastewater surveillance. COVID is now widely monitored in wastewater, as are other diseases like flu, RSV, and even Mpox (formerly known as monkeypox). An ideal scenario: if pre-existing wastewater surveillance systems are able to screen for potential pandemic pathogens like Ebola, Nipah, and others, giving experts a warning that an outbreak may soon occur, Meadows said.

Even if widespread wastewater surveillance isnt economically feasible, wastewater programs at major international airports like those stood up during the pandemic could alert public health officials to the arrival of such pathogens from overseas, Nita Madhav, senior director of epidemiology and modeling at Ginkgo, told Fortune. Its crucial, she added, that the world maintain the surveillance structure built during COVID for use during future pandemics.

Both Meadows and Madhav said they hope researchers and the public alike dont fall into the classic pandemic panic-neglect cycle that ensures the world is never quite ready for the next global health catastrophe.

Aside from maintaining and even improving on the surveillance network built during the COVID pandemic, Madhav said, theres more that can be done to prevent future pandemics, including small changes made on an individual level.

Pandemics and epidemics are not a foregone conclusion, Madhav said, if we can reduce drivers of risk like climate change, and implications of human interaction with land. Its really powerful that people can make personal choices that directly impact how this plays out over the next decades.

Some actions consumers can take to reduce climate change, according to the United Nations, Natural Resources Defense Council, and Imperial College London:

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These 4 lethal viruses could fuel the next pandemic, new research says. What they areand how the world can prepare - Fortune