Pandemic: Virus hunters track the next threats

In labs around the world, a network of doctors and researchers is working to identify new viral threats, some of which are linked to climate change, in hopes of preventing the next pandemic.

This coalition of “virus hunters,” as it calls itself, has already discovered all sorts of new ailments, from an unusual tick-borne disease in Thailand to the surprise outbreak in Colombia of an infection carried by midges.

“The list of things we need to worry about, as we’ve seen with COVID-19, is not static,” says Gavin Cloherty, an infectious disease expert who leads the Abbott Pandemic Defense Coalition. “We need to keep a close eye on how the bad guys we already know are evolving, but also the new ones that are coming along,” he says.

Funded by US healthcare and medical device giant Abbott, the coalition brings together doctors and researchers from around the world. By uncovering new threats, the coalition gives Abbott a head start in designing test kits like those that have been at the heart of the response to the Covid-19 crisis. And the support of a major industrial group gives the coalition significant resources to detect, sequence and combat new viruses. “When we find something, we are able to very quickly produce diagnostic tests at the industrial level,” says Cloherty. “The idea is to contain an epidemic, so as to prevent a pandemic.”

Since it began in 2021, the coalition has sequenced some 13,000 samples. In Colombia, it discovered an outbreak of Oropouche, a virus spread by midges and mosquitoes that had rarely been seen in that country before. Phylogenetic work to trace the strain’s family tree revealed that it originated in Peru or Ecuador rather than Brazil, another hotspot.

More recently, the coalition, working with Thai doctors, discovered that a tick-borne virus was causing a mysterious “cluster” of cases in Thailand.

Testing and sequencing of samples from 2014 revealed that many of the patients had severe fever with thrombocytopenia syndrome (SFTSV), a condition that had only been diagnosed about a dozen times before in Thailand. Monitoring for such threats is increasingly necessary.

The link between climate change and these types of diseases is well established and multifaceted: warmer temperatures allow vectors like mosquitoes to settle in new areas, heavier rainfall creates more breeding grounds, and extreme weather forces people outdoors, where they are more vulnerable to bites. Humans’ impact on the planet also fuels the spread and evolution of infectious diseases in other ways: loss of biodiversity forces viruses to evolve to new hosts, and can push animals into closer contact with humans.

Phylogenetic analysis of the Thai SFTSV strain provides insight into these complex interactions. It demonstrated that the virus evolved from a tick species with a restricted geographic range to the more resilient Asian longhorned tick.

This evolution is largely due to the use of pesticides that reduced the number of host ticks. After evolving, the virus was able to spread further, in part because Asian long-horned ticks can live on birds, which are moving further and faster due, again, to climate change.

The footprints of climate change are everywhere, from record dengue outbreaks in Latin America and the Caribbean to the spread of West Nile virus in the United States.

The global spread of Covid-19 has been a powerful reminder of the risks of infectious diseases. But, Cloherty says, we are quickly forgetting that lesson. “We have to be vigilant,” he says. “Something that happens in Bangkok could happen in Boston tomorrow.”