Climate change is changing the geography of infectious disease

Europe isn’t just at risk of the direct effects of climate change, it is also exposed to the indirect effects of infectious disease like dengue, chikungunya and West Nile Virus – which are expanding their territories northward.


Issued on: 01/07/2025 -
FRANCE24
By:Diya GUPTA

Salt Lake City Mosquito Abatement District biologist Nadja Reissen examines a mosquito in Salt Lake City, Aug. 26, 2019. © Rick Bowmer, AP

Europe is unusually hot. Several cities in France have been placed on an ‘unprecedented’ high alert on Tuesday, Spain recorded a scorching high of 46 degrees Celsius on Monday while wildfires in Turkey caused by a heatwave have forced more than 50,000 people to be evacuated from five regions in the western province of Izmir.

While the heat is uncharacteristically strong, extreme weather is no longer a surprise. Science agrees that climate change caused by steadily increasing greenhouse emissions has been the primary factor for the scorching new reality that the world is forced to adapt to, be it heatwaves, floods, droughts or extreme cold.

While the cumulative meteorological changes might make life more difficult for people, bacteria, pathogens and viruses are thriving in a world that’s getting hotter and more humid. Climate change is bringing ‘tropical’, climate sensitive illnesses up north, into Europe, shifting the geography of global infectious disease.

The migration of disease

“Over half of all infectious diseases confronted by humanity worldwide have been at some point aggravated and even strengthened by climatic hazards,” says Dr Aleksandra Kazmierczak, an expert on the relationship between climate change and human health at the European Environment Agency (EEA).

Kazmierczak says that climatic conditions have made Europe more suitable for vector and water borne disease. ‘There is a northward, temporal shift because the current climate is more suitable for pathogens. Disease season is longer – ticks, for example, are now active all year round in many places.”

One of the fastest growing infectious diseases in Europe is dengue. 304 cases were reported in Europe in 2024 alone – compared to 275 cases recorded in the previous 15 years combined.

05:11

DOWN TO EARTH © FRANCE 24

The main culprit behind dengue is the Asian tiger mosquito, or Aedes albopictus. The insect is what’s known as a vector, i.e. a living organism that can transmit infectious pathogens between humans or from animals to humans. With its distinctive black and white stripes that resemble those of a zebra more than a tiger, the mosquito is capable of transmitting dengue, zika and chikungunya.

Europe only experienced a handful of diseases carried by the tiger mosquito per year right up until the late 90’s. Most were one-off cases brought home by travelers from South East Asia – Aedes albopictus’s native home. But with increased travel and globalization, the insect’s journeys westward increased. It hopped onto cargo carriers to Albania or hitched a ride to the warmer parts of France and moved to Europe, where it remains to this day.

Read moreHow the tiger mosquito invaded France and what can be done to stop it

In 2006, France officially declared dengue a notifiable disease. In 2022, its presence was detected in most of the French mainland administrative departments. The insect quickly adapted itself to urban environments, where it needs just one still body of water – an undisturbed pond or a neglected watering can – to reproduce and proliferate.

The numbers have jumped so dramatically that scientists now believe that the diseases carried by Aedes albopictus will become endemic in Europe. Some researchers even say that the number of dengue and chikungunya outbreaks could increase five-fold by 2060 compared to current rates.

The tiger mosquito is a known carrier of several pathogens and viruses. Climatic conditions have contributed to a geographic range expansion of several other vectors like ticks and other species of mosquitos and flies, which carry their own diseases like West Nile Fever, Lyme disease and tick-borne encephalitis.

Firefighters work at a cite of a flooding, near Stronie Slaskie, southwestern Poland, Thursday, Sept. 19, 2024. © Tomasz Fijolek, AP

But unfortunately, it isn’t just the bugs we need to be worried about.

Climate change could also increase the occurrence of water-borne disease. In recent years, Europe has experienced the devastating impact of extended period of rain and floods, which wreak havoc on water treatment and distribution systems. Water can gather several pathogens from dumps, fields and pastures and flush them into water treatment and distribution systems.

Kazmierczak also warns of pathogens carried in the sea: "As the arctic melts; salinity in seawater decreases, making it ideal for pathogens like vibrio. It’s been seen more in the Baltic and North Seas. It is transferred from seafood or even exposure in an open wound if you’re swimming in infectious water."
Unearthing the zombie viruses

Permafrost covers almost 15 percent of the northern hemisphere, a significant portion of which is concentrated in Siberia, Alaska and Greenland. As the name implies, permafrost is soil and rock that stays frozen for at least two consecutive years. It acts almost like a cold storage for history: mammoths, saber-toothed tigers and long extinct plants have been preserved, almost entirely intact.

Some of what's stuck in frozen limbo isn't even dead – it's just dormant. Numerous ‘zombie microbes’ have been discovered in melting permafrost over the years, some after millennia. Researchers have raised fears that a new global medical emergency could be triggered – not by an illness new to science but by an ancient disease which modern human immunity is not equipped to deal with. The melting permafrost could also release old radioactive material and banned chemicals that had been dumped as waste.

In this photo provided by the United States Geological Survey, permafrost forms a grid-like pattern in the National Petroleum Reserve-Alaska, managed by the Bureau of Land Management in Alaska. © David W. Houseknecht, AP

This was the case in 2016, when over 2000 reindeer were found dead in Siberia because of an anthrax outbreak. Melting permafrost thawed the carcass of a reindeer that had died decades ago and unleashed the dormant virus into the modern world. Dozens of people living nearby had to be hospitalized.

This bizarre new threat may be another consequence of warming global temperatures, despite sounding like it’s been pulled from the pages of a science fiction novel. But Kazmierczak says that the research is still in its nascent stages and permafrost exists in isolated regions with little habitation.
Adapting to a new environment

The changes in the geography of infectious disease, to a large extent, cannot be undone. Temperatures in Europe have already risen by over 2 degrees in the last decade alone, with no sign of it slowing down.

But despite the warming climate, Kazmierczak is hopeful that Europe can adapt. “National health infrastructures and awareness will be paramount in our adaptation. We already have examples from countries that have already dealt with these illnesses, and we can adapt them to Europe.

“We believe that a way to reduce our carbon footprint is also to bring nature into cities and homes – but hosting vectors, for example, is exactly the flipside that it can have. We need to make sure that we adapt with awareness.”

Taking control: zombie stories are rooted in reality

Credit: Naughty Dog/HBO.

June 15, 2025

Imma Perfetto

Cosmos science journalist

We are taking a look back at stories from Cosmos Magazine in print. From parasitic wasps to body-hijacking fungi, the natural world is full of real-life zombification. But could our favourite post-apocalyptic TV shows come true? Imma Perfetto investigated in September 2023.

The Last of Us, The Walking Dead, World War Z, Zombieland, Shaun of the Dead… I could keep going but I think you get the gist.

Zombies are everywhere in fiction, from movies to TV shows, video games to books.

These stories are usually pretty hand-wavey about the actual science that has turned humans into mindless, shambling, killing machines, but you might be surprised to know that there are actually some pretty gruesome examples of zombification in real life.

If you can stomach it, come with me on a tour into the lives of parasitic wasps, worms, single-celled organisms, fungi, viruses – and even into our own brains.

Horror authors and script writers, listen closely – because we all know that some of the scariest stories are the ones rooted in reality.

I could keep going – there are so many more thrillingly grisly examples of zombification in nature – but you might need some fresh air and recovery time.

“Nature is rife with examples of parasitic puppeteers infecting their host.”

Just one more thing before you go. These examples of zombification fit the major zombie stereotypes: increased aggression, a loss of ­autonomy and a compulsion to bite or to ensure the spread of the parasite or virus infecting the host. But thankfully, there aren’t any known diseases or afflictions in nature that can continuously reanimate corpses – so the undead remain firmly within the realms of fantasy.

Maybe that will help you rest easy at night – or maybe I’ve already infected your nightmares with mind-controlling worms and fungi that will ­consume you from the inside out.

Sweet dreams.

Not your typical swimming lesson

Credit: Greg Barton

The first stop on our super fun and not-at-all ­distressing zombie extravaganza is parasites. These are organisms that live on or inside an organism of another species, its host.

Gordian worms, also known as horsehair worms, are long, thin parasitic worms found in fresh water all over the world. The larvae bore into the body of a host, initially other larvae in the water, which then get snatched up and eaten by unfortunate insects like grasshoppers or crickets. There, the worm grows inside the insect’s body cavity to as long as 30 centimetres, secreting digestive enzymes from their skin to absorb their host body’s nutrients.

If that isn’t spine-chilling enough, it gets worse. Hosts infected with a gordian worm will, despite avoiding water in all other cases, perform a deadly cannonball into the next aquatic environment they come across and drown. The worm then bursts out of a borehole and swims off in search of a mate, starting the cycle all over again.

How the worms manage to manipulate the insects’ cognitive functions is not fully understood, but researchers believe the worms produce molecules that act on the development of their host’s central nervous system, thus altering physiological responses and behaviours.

Home sweet zombie spider home

Credit: Greg Barton

If those tapeworms from hell made you squeamish, get a sick bucket ready because there are far worse parasites to contend with.

Nature is rife with examples of parasitic ­puppeteers infecting their host and inducing some pretty strange behaviour. One of my favourites is from a 2018 study published in Ecological Entomology, which discovered a previously unknown species of wasp deep in the Ecuadorian Amazon jungle – with the ability to transform a species of spider into a zombie-like drone.

These spiders (Anelosimus eximius) are known for living together in large colonies, where they cooperate to hunt and parent. Think Aragog and his giant Acromantula children chilling together in Hogwarts’ Forbidden Forest.

But the study, led by scientists from the University of British Columbia in Canada, found that Zatypota wasps intrude on this idyllic social life by laying eggs on the abdomens of the spiders, which then hatch into larvae that feed on the ­spider’s internal body fluid. The larvae finally take ­complete control of the spider’s body, hijacking its brain and triggering some unusual behaviour.

The researchers don’t know yet how the wasps manage total control, but suspect it may involve the wasp larva injecting hormones into the spider.

The result is that the spider does something against its own behavioural tendencies: it leaves the colony and builds a densely woven, cocoon-like nest where the larvae can grow safely and comfortably into adult wasps, devouring their host in the process.

Delicious.

This fungus is trending

Credit: Greg Barton

We can’t cover real-life inspirations for zombie apocalypses without talking about Cordyceps. It’s possibly the world’s most infamous fungus thanks to its starring role in the video games The Last of Us Parts I and II, as well as the live-action TV ­adaptation released earlier this year.

Cordyceps and Ophiocordyceps are genera of fungi that include about 750 species worldwide, most of which are parasitic and infect insects and other arthropods, like carpenter ants and trapdoor spiders. Infection starts when a fungal spore gets inside an organism, like an ant, and begins growing.

The ant’s behaviour gets hijacked and it prioritises its parasite’s reproduction over everything else. It stops foraging for the colony and communicating with its nest mates, becomes hyperactive and wanders off on its own to find a spot to climb up to.

It then chomps down on a piece of vegetation in a move called the “death grip”. The muscles in its mandibles then atrophy, locking it in place for the final throes of its life.

The fungus consumes everything inside the host, killing it, then uses those nutrients to sprout a fruiting body out the top of the host’s head. Spores form and drift off to infect more unwary hosts.

How is this piece of horrid biology possible? Again, it comes down to secreted chemicals and their effect on the host’s physiology. For example, a 2015 study led by researchers at Pennsylvania State University in the US identified a range of secreted proteins produced increasingly by the fungi during the strange biting behaviour. These may affect a range of processes including immune responses, stress responses and impairing the production of chemicals used in communication between insects.

It’s a viral sensation

Credit: Greg Barton

This deep-dive into grossity wouldn’t be complete without mentioning rabies – the virus that inspired the zombies of the horror classic 28 Days Later.

A rabies infection has all the symptoms of your typical zombie: a compulsive need to bite, a fear of light and mindless aggression. The virus is usually transmitted through bites and scratches from an infected animal, and it takes time to travel to the brain before causing symptoms – which is absolutely essential if you’re going to have the ­requisite scene where a person tries to hide their bite, but gets progressively sicker until the group confronts them and finds out they’re infected.

This incubation period typically lasts 2–3 months for rabies, but can vary from one week to a year. Rabies progresses to the central nervous system where it causes inflammation of the brain and spinal cord, triggering symptoms in two different forms.

There’s paralytic rabies, which occurs in about 20% of human cases. Here, muscles become progressively paralysed, and the person falls into a coma before dying.

Then there’s furious rabies, like your more World War Z flavour of zombie, which causes irrational aggression, hyperactivity, hallucinations and a fear of water and fresh air.

A catastrophe waiting to happen

Credit: Greg: Barton

A little closer to home, there’s the single-celled parasite Toxoplasma gondii that infects the brains of our kitty cats, and ours too.

A 2014 study published in PLoS ONE actually estimates that up to half of the world’s human ­population is infected, though most of us have no symptoms. That’s pretty alarming to contemplate, since Toxoplasma has been shown to change the behaviour of infected mice, who become hyper­active and lose their innate fear of cats – in some cases even appearing to be attracted to them.

There’s evidence that also suggests toxo­plasmosis might be linked to personality changes in humans too. One study found an ­association with impulsivity in younger men and increased aggression in women, while another found a positive association between national homicide rates and prevalence of the parasite in the population – although correlation is not causation.

Originally published by Cosmos as Taking control: zombie stories are rooted in reality

 

Zombie cells in the sea: Viruses keep the most common marine bacteria in check

MAX PLANCK INSTITUTE FOR MARINE MICROBIOLOGY

 

IMAGE: 

SUNSET OVER THE ISLAND OF HELGOLAND IN THE GERMAN BIGHT, WHERE THE RESEARCHERS FROM THE MAX PLANCK INSTITUTE FOR MARINE MICROBIOLOGY OBTAINED THEIR SAMPLES.

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CREDIT: JAN BRÜWER/MAX PLANCK INSTITUTE FOR MARINE MICROBIOLOGY

The ocean waters surrounding the German island of Helgoland provide an ideal setting to study spring algae blooms, a focus of research at the Max Planck Institute for Marine Microbiology since 2009. In a previous study, the Max Planck scientists observed a group of bacteria called SAR11 to grow particularly fast during these blooms. However, despite their high growth rates, the abundance of SAR11 decreased by roughly 90% over five days. This suggested that the cells were quickly decimated by predators and/or viral infections. Now, the Max Planck researchers investigated what exactly lies behind this phenomenon.

Finding the phages infecting SAR11

“We wanted to find out if the low numbers of SAR11 were caused by phages, that is viruses that specifically infect bacteria”, explains Jan Brüwer, who conducted the study as part of his doctoral thesis. “Answering this seemingly simple question was methodologically very challenging”.

How does phage infection work? Phages infect bacteria by introducing their genetic material into them. Once there, it replicates, and utilizes the bacterial ribosomes to produce the proteins it needs. Researchers from Bremen used a technology that enabled them to “follow” the phage’s genetic material inside the cell. “We can stain the specific phage genes and then see them under the microscope. Since we can also stain the genetic material of SAR11, we can simultaneously detect phage-infected SAR11 cells”, explains Jan Brüwer.

While this might seem straightforward, the low brightness and small size of the phage genes made it challenging for researches to detect them. Nonetheless, thousands of microscope images were successfully analyzed, bringing some exciting news.  

“We saw that SAR11 bacteria are under massive attack by phages”, says Jan Brüwer. “During periods of rapid growth, such as those associated with spring algae blooms, nearly 20% of the cells were infected, which explains the low cell numbers. So, phages are the missing link explaining this mystery.”

Zombie cells: A global phenomenon

To the surprise of the scientists, the images revealed even more. "We discovered that some of the phage-infected SAR11 cells no longer contained ribosomes. These cells are probably in a transitional state between life and death, thus we called them 'zombie' cells”, Brüwer explains.

Zombie cells represent a novel phenomenon observed not only in pure SAR11 cultures but also in samples collected off Helgoland. Furthermore, analysis of samples from the Atlantic, Southern Ocean, and Pacific Ocean revealed the presence of zombie cells, indicating this phenomenon occurs worldwide.

“In our study, zombie cells make up to 10% of all cells in the sea. The global occurrence of zombie cells broadens our understanding of the viral infection cycle”, Brüwer emphasizes. “We suspect that in zombie cells, the nucleic acids contained in the ribosomes are being broken down and recycled to make new phage DNA.”

Brüwer and his colleagues hypothesize that not only SAR11 bacteria, but also other bacteria, can be turned into zombies. Thus, they want to further investigate the distribution of zombie cells and their role in the viral infection cycle.

“This new finding proves that the SAR11 population, despite dividing so fast, is massively controlled and regulated by phages”, stresses Brüwer. “SAR11 is very important for global biogeochemical cycles, including the carbon cycle, therefore their role in the ocean must be redefined. Our work highlights the role of phages in the marine ecosystem and the importance of microbial interactions in the ocean”.

Infected cells and zombie cells 

Under the microscope, scientists identified SAR11 zombie cells by their distinct lack of ribosomes. In an example comparing a live, infected SAR11 cell to an infected zombie cell: blue indicates bacterial DNA, yellow shows ribosomes, and purple highlights phage genes. The live cell (upper pictures) displays all three colors, while the zombie cell (lower pictures) lacks the yellow ribosome signal. The final column of images on the right merges these colors, clearly distinguishing the two cell types.

CREDIT

Jan Brüwer/Max Planck Institute for Marine Microbiology

JOURNAL

Nature Communications

DOI

10.1038/s41467-024-48172-w 

ARTICLE TITLE

Globally occurring pelagiphage infections create ribosome-deprived cells

LA REVUE GAUCHE - Left Comment: Search results for BACTERIOPHAGE 

 

Developing a vaccine for the “zombie drug” xylazine

Scripps Research chemical biologists design an early “proof-of-concept” vaccine that could lead to the first effective treatment of xylazine overdose in people

SCRIPPS RESEARCH INSTITUTE

LA JOLLA, CA—Xylazine is an FDA-approved sedative and pain reliever for use in animals, but it has severe adverse effects when used in humans. It is now illicitly being added to opioids, like fentanyl and heroin, as well as cocaine—leading to a sharp rise in overdose deaths.

Now, Scripps Research chemical biologists have developed a vaccine to block the effects of xylazine’s toxicity. The vaccine works by training the immune system to attack the drug, which is described in a new paper published in Chemical Communications on April 1, 2024.

“We demonstrated that a vaccine can reverse the symptoms of a xylazine overdose in rodents,” says study senior author Kim D. Janda, PhD, the Ely R. Callaway, Jr. Professor of Chemistry at Scripps Research. “There is currently no remedy for xylazine poisoning other than supportive care, thus, we believe our research efforts and the data we have provided will pave the way for an effective treatment in humans.”

The rapid increase in lethal drug overdoses attributed to xylazine combined with fentanyl prompted the White House Office of National Drug Control Policy to declare this combination an emerging threat to the United States. Xylazine intoxication presents similarly to opioid overdose, causing respiratory and central nervous system depression, and it can heighten the effects of opioids. However, naloxone—typically administered to reverse the effects of opioids—does not tackle the impact of xylazine, highlighting the need for effective measures to treat acute toxicity caused by xylazine.

Researchers suspect xylazine works by reducing blood flow to the brain, among other areas of the body. The drug also causes non-healing skin lesions and wounds, often located on the forearms and lower legs, that can require amputation in some cases—giving it the nickname “zombie drug.”

Although no treatment currently exists, targeted vaccines may offer a solution. Vaccines nudge the immune system to create antibodies to fend off invaders. Antibodies can target viruses, bacteria and toxins. However, sometimes molecules are too small to initiate an immune response, as is the case with xylazine. So, to circumvent this problem, the researchers created a vaccine using a design principle that Janda pioneered, which relies on pairing the drug molecule (called a hapten) with a larger carrier molecule (a protein) and an adjuvant.

In this study, the scientists combined a xylazine hapten with multiple different protein types, to see which combination would create a robust immune response against xylazine. The team tested three vaccine formulations (termed TT, KLH and CRM197, based on the protein involved) to see which vaccine cocktail could help rodents after being challenged with xylazine. One of the three vaccines (TT) significantly increased movement in mice given xylazine after 10 minutes, while two of the three vaccines (TT and KLH) led to an improvement in breathing.

The scientists also examined how these vaccines would limit xylazine blood brain barrier, (BBB) permeation, a filtering mechanism that scrutinizes drug penetration. When xylazine was injected, it immediately crossed into the brain to bind with receptors. Antibodies typically cannot navigate the BBB; however, two of the three vaccines (TT and KLH) showed a strong ability to stop xylazine from reaching its receptors in the brain, limiting its detrimental effects.

A provisional patent has been filed on the research. In the future, his team will build off this work to create a bifunctional antibody that will reverse both fentanyl and xylazine’s toxicity simultaneously, something that naloxone cannot do.

“A monoclonal antibody treatment could be given in tandem with the vaccine to provide both immediate and long-term protection from both opioid substance use disorders as well as opioid-xylazine overdoses,” says Janda. “This strategy could make a significant impact on the opioid epidemic.”  

“Evaluation of a Hapten Conjugate Vaccine Against the ‘Zombie Drug’ Xylazine” was co-authored by Mingliang Lin, Lisa M. Eubanks, Bin Zhou, and Kim D. Janda, all of Scripps Research.

Funding for the study was provided by the Shadek family and Pearson Foundation.

 

About Scripps Research

Scripps Research is an independent, nonprofit biomedical institute ranked one of the most influential in the world for its impact on innovation by Nature Index. We are advancing human health through profound discoveries that address pressing medical concerns around the globe. Our drug discovery and development division, Calibr, works hand-in-hand with scientists across disciplines to bring new medicines to patients as quickly and efficiently as possible, while teams at Scripps Research Translational Institute harness genomics, digital medicine and cutting-edge informatics to understand individual health and render more effective healthcare. Scripps Research also trains the next generation of leading scientists at our Skaggs Graduate School, consistently named among the top 10 US programs for chemistry and biological sciences. Learn more at www.scripps.edu.

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DOI

10.1039/D4CC00883A 

The couple trying to keep killer ‘zombie viruses’ at bay – and protect us from another pandemic

Simon Usborne
Sun, 18 February 2024 

Jean-Michel Claverie and Chantal Abergel in their laboratory just outside Marseille - Jeremy Suyker

Jean-Michel Claverie was already at retirement age when he travelled to Siberia to hunt for ancient viruses in the Arctic. After a long career as a research scientist – and 25 years since he had set up a laboratory outside Marseille with his wife Chantal Abergel – he could have put his feet up. He and Abergel, who is 62, commute to their lab from a comfortable house near the pretty harbour town of Cassis. But Claverie, who was about to turn 70, had no intention of hanging up his lab coat.

It took days, several flights and a ride in a rickety boat made from old war plane parts to reach the banks of the Kolyma river west of Chersky, a remote town not far from the East Siberian Sea. Once a transit hub for Soviet Gulags, Chersky and its river had become a magnet for scientists trying to unearth secrets from the frozen deep.

At a tight bend in the river he set up a makeshift research station inside a tent and from there, he and a small team began removing soil from the steep-sided riverbank to expose earth that has been frozen for 30,000 years.

A layer of this hardened soil and sand, known as permafrost, lies beneath the earth’s surface across vast areas of the northern hemisphere, largely in Arctic regions of Russia, Scandinavia and North America. In places such as Chersky, the permafrost stays below freezing even while the summers are hot and the surface landscape verdant. In some Arctic regions, life in this layer has been suspended for around 700,000 years.

But climate change and rising temperatures mean that permafrost is now thawing. As a result, powers including Russia, China and the US are stepping up efforts to drill and dig through it in pursuit of precious metals and fossil fuels.

Suspended within this thinning layer, however, are the preserved remnants of prehistoric life. Some of it – including viruses – may yet return from the dead with unknown consequences.

I meet Claverie, who is now 73 and wears blue jeans and running shoes, in the genomic and structural information lab at Aix-Marseille University, where he is now a professor emeritus. He and Abergel, an experimental biologist who runs the lab, lead an international team of a dozen researchers in a stout concrete building on a hilltop campus between Marseille and Cassis.

Claverie (pictured) points out that we still don’t know for certain what role viruses might have played in the demise of major species such as Neanderthals or woolly rhinos - Jeremy Suyker

Inside a small lab with a yellow biohazard danger sign on the door, alongside the logo for the Back to the Future film, Claverie pulls a small plastic bag out of a freezer. It contains what looks like the damp remains of a sandcastle. It is in fact thawed Siberian permafrost. During his two-week field trip, Claverie’s team used a drill with a cup-shaped coring bit to prize more than 20 such samples from the banks of the Kolyma. He brought them back to the French Riviera in his suitcase.

The team study these, as well as permafrost samples already stored in scientific institutes, in a race to understand the microbes suspended within them. While virology research tends to focus on threats lurking in more tropical climates, Claverie and Abergel are searching for potential dangers now emerging from the frozen north, including what have become known as ‘zombie viruses’.

‘The real danger would be to be confronted with viruses we’ve never seen before,’ Claverie tells me in the lab, where a low winter sun streams through a high window. He points out that we still don’t know for certain what role viruses might have played in the demise of major species such as Neanderthals or woolly rhinos.

And consider, he says, the huge efforts required to suppress pathogens already familiar to science, such as the coronaviruses. ‘So think about a totally new virus that might have caused [an] extinction. What happens if it comes back?’

Claverie and Abergel fell in love at a science conference in a French ski resort in 1987. They were both interested in the then emerging field of bioinformatics – the use of computers to make sense of biological data. In 1995, after working in the US for five years, the couple settled in Marseille, where Abergel had grown up, to establish their lab. They now have two grown-up sons – a chef and an engineer.

The couple occupy neighbouring offices above the labs. ‘We had to work together at home in the pandemic and Jean-Michel was upset because I was making too much noise,’ Abergel tells me at her desk, which is next to a vast potted Flamboyant tree she planted as a seed. ‘It is very capricious and has never flowered,’ she adds with a smile.

Abergel: 'We’re both stubborn and, like all scientists, we always think we’re right' - Jeremy Suyker

Claverie had enjoyed an early career as a nomadic researcher in multiple fields, including theoretical physics. The lab’s early work involved the sequencing of bacterial genomes – the genetic information that defines organisms. The switch to virus research was accidental. A sample that had originally come from a hospital in Bradford as part of a search for the origins of a pneumonia outbreak contained what scientists had assumed was a new type of bacteria. On closer inspection in Marseille, the bacteria turned out to be a virus that broke all the rules.

There are more viruses than stars in the universe and most remain undiscovered. They lurk anywhere there is life – in the sea, soil and air – but only replicate when they meet a host. They were always thought to be tiny and genetically simple, containing only what they needed to invade cells, replicate and move on. The new microbe from Bradford was orders of magnitude larger and more complex than any known virus. ‘I can still remember when we got the image from the microscope,’ Claverie recalls. ‘I said, “Jesus, what is this?!”’

They named it Mimivirus. The discovery stunned the field of virology, which was concerned largely with diseases caused by viruses in humans, livestock and agriculture. Viruses existing in the wild without a known host had flown under the radar. Mimivirus opened a new field of research. ‘This was the start of environmental virology,’ says Claverie, who quickly refocused his lab’s work.

For several years, the team discovered more giant viruses, which they helped detect by introducing amoebas to samples; if the single-cell organisms died, it signalled the presence of a virus and the need for further research. This work, which added to wider understanding of viruses and how they interact with hosts, found a new avenue in 2013 when Claverie read a Russian paper about the regeneration of a plant from fruit tissue that had been frozen in the Siberian permafrost for 30,000 years. ‘I thought, if they can revive a plant, can we revive a virus?’

The ground floor of the building in Marseille is divided into a series of modest labs, many cluttered with microscopes, chemicals, glass flasks and beakers. While Claverie is the de facto chief virus hunter, Abergel has led the development of the techniques used to isolate and study them. ‘We complement each other well, even if we sometimes fight,’ she says. ‘We’re both stubborn and, like all scientists, we always think we’re right.’

Machines and air-conditioning units hum in the background, maintaining climates for each stage of the process. One of the machines, called a ‘mosquito robot’, incorporates 96 needles capable of inserting virus proteins into wells containing different culture conditions. In another room, the amoebas that are used as bait to catch viruses are grown and stored. When a virus is detected in a sample, technicians purify and amplify it before its DNA can be sequenced.

Claverie can’t remember who first used the word ‘zombie’ in relation to his virus work. Certainly it did not appear in his landmark paper in 2014, which detailed the first revival of a virus preserved in permafrost. He named the microbe, which he found in an existing, 30,000-year-old sample taken from ground not far from Chersky, ‘Pithovirus sibericum’. Not long after the discovery, a specialist toy company made a stuffed Pithovirus, added a cute smile, and called it Zombie Virus. ‘The whole thing started going crazy,’ Claverie says.

A permafrost sample - Jeremy Suyker

The sci-fi name challenged Claverie’s academic instincts but it has also amplified his and Abergel’s research over a decade in which the climate crisis has become more urgent. The couple have continued to revive more than a dozen distinct viruses from permafrost, including in the last meals found in the frozen stomachs of woolly mammoths. In one case they reanimated a virus that had hibernated for 50,000 years.

None of these viruses would pose a risk to humans even beyond the controlled environment of the Marseille lab; they are specific to their amoeba hosts. But the scientists are anxious to raise awareness of potential threats that may still emerge. ‘If there are viruses that have been preserved for 50,000 years, there will probably be others from long before that,’ Claverie says. ‘The human species is only 200,000 years old. We don’t know what kind of viruses existed before that and we’re certain our immune systems were never exposed to them.’

There have been early warning signs of the health effects of climate change in the Arctic. In 2016, a young boy and thousands of livestock died in the Yamal-Nenets region of Russia when a reindeer that had been dead for decades thawed in a record heatwave, releasing the anthrax bacteria.

Scientists fear that centuries-old shallow graves that herders used for livestock (firewood being too scarce to burn carcasses) may become anthrax infection sites, although the disease is not contagious between people. Meanwhile, the DNA of the smallpox and influenza viruses has been detected in human corpses that had been frozen for over a century. Those samples were not revived and even the deadliest virus poses no threat if it remains locked in permafrost. But Claverie fears that this may be about to change.

Over the past four decades, the Arctic has warmed up four times faster than the global average – and up to seven times faster in parts of Norway and Russia. A doom loop known as Arctic amplification involves the absorption of more sunlight as a result of the loss of reflective ice, leading to further warming and melting.

View from Chersky stone hill, Siberia - Alamy Stock Photo

Melting ice is bad news for polar bears and other Arctic fauna but there is perhaps less awareness of the effects of thawing permafrost. Earth that has been frozen solid is turning to mud, causing giant sinkholes to open up. Phone lines, roads, airport runways and whole towns are at risk.

Meanwhile, the thawing of organic matter within permafrost is releasing vast quantities of methane, creating a second vicious cycle as the potent greenhouse gas exacerbates global warming. These effects strike fear into the hearts of scientists, but present opportunities to businesses and nations still struggling to break bad habits. Melting sea ice is opening up shipping routes to support growing industrial exploitation of thawing ground that is becoming more viable as a source of minerals and fuel.

Russian nuclear-powered icebreakers are supplying plants that make up the growing Yamal liquified natural gas project. In Norway, Canada and the US, prospectors are eyeing up Arctic ground for the precious and rare metals and minerals needed to power technology such as batteries for electric vehicles. As workforces the size of large towns gather at these sites, Claverie worries about the potential threat of exposure to viruses that may be churned up in the course of drilling and digging.

‘There are a lot of sharks in Australia, but if you don’t go surfing, that’s fine,’ he says, reaching for a metaphor from an even warmer climate to illustrate the point that there is no danger without exposure to an underlying hazard. ‘But now, with the development of industrial activities in the Arctic, we are going to have contact with these things.’

Then there are the effects of Covid. The pandemic has been positive for investment in viral research, but Claverie is also concerned that this is bringing us closer to danger. Parts of the scientific community are going out in search of exotic viruses that they know are deadly to humans. Yet one bite from a bat in the field, or a slip of a needle, is all it can take for a disastrous outbreak to occur.

Claverie shows me two photos from an Arctic research centre in which a baby mammoth carcass is laid out on a slab. In the official image, scientists wear masks and full-body protective suits. In another snap taken privately, a small crowd in everyday clothing gathers around the animal as if it were an item on Antiques Roadshow. ‘There are scientists in Russia who are already trying to revive viruses that infected mammoths and woolly rhinos,’ the professor adds. ‘This is totally stupid and dangerous. You do not revive viruses that infect animals.’

Jean-Michel Claverie was nearly 70 when he travelled to Siberia to study 'zombie viruses' - Jeremy Suyker

Claverie is part of an increasingly vocal campaign within the science community to prioritise surveillance over prospecting, finding sick patients early rather than investing millions in the risky search for pathogens in the wild. The Marseille lab is now part of UArctic, a consortium of educational institutes that is working to establish a monitoring network and quarantine protocols in the event of an infection from a permafrost virus. ‘The idea is that you capture the virus before it becomes a pandemic.’

Yet scientific cooperation with Russia, which has the largest share of permafrost (two-thirds of the country sits above it), has been on ice since the invasion of Ukraine in 2022, blocking access to researchers and samples. Claverie is worried about this collaborative breakdown, as well as Putin’s disregard for climate targets and rush to exploit Arctic resources. ‘My trip was funded partly by the Russian Academy of Sciences,’ he says. ‘Those things don’t exist any more, they are frozen.’

Up in Claverie’s own office, fragments of mammoth bones sit on a bookshelf. The professor smuggled them out of Russia along with his permafrost samples in 2019. He is glad he was able to make it to Siberia before the pandemic and the Ukraine invasion. Either way, he sees no reason to return now he has proved his point: that the world should be alert to the viruses that may be released from thawing permafrost.

He has grave concerns about the future but does not come across as a doomsayer; he is driven by a natural curiosity and passion for science. Work at the lab goes on to find viruses in existing samples, including thousands stored at a polar research institute near Hamburg. Meanwhile, he has expanded his interest south to Antarctica.

He tells me he has already made promising discoveries in samples of sediment he asked scientists on an Italian research vessel to retrieve from beneath the Ross Sea in 2022. Only a last-minute change of the expedition’s budget prevented him from travelling to the frozen south himself. As he sails through his notional retirement in Marseille, he says Abergel’s relative youth, apart from anything else, keeps him working. ‘Perhaps when she retires I will stop, but until then I’m not going to go on a cruise by myself,’ he says, before returning to his screen.

 

It's award season: let's celebrate microbes in movies

A review in FEMS Microbiology Letters by Professor Manuel Sanchez from UMH (Spain) reveals how movies can raise public awareness and appreciation of the world of microbiology

Peer-Reviewed Publication

UNIVERSIDAD MIGUEL HERNANDEZ DE ELCHE

 

IMAGE: 

DEAD ANT INFECTED WITH OPIOCORDYCEPS UNILATERALIS, BY DAVID P. HUGHES, MAJ-BRITT PONTOPPIDAN. WIKIMEDIA COMMONS / PEDRO PASCAL AND BELLA RAMSEY IN THE HBO SERIES "THE LAST OF US" (2023).

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CREDIT: UMH

Elche (Spain), January 22, 2024. Usually, show business depicts viruses, bacteria, and other microorganisms as one of the worst menaces to humankind. Entertainment movies influence the way audiences understand and perceive these topics. Yet, few films accurately portray the science of microbiology and its social implications. Movies and TV series often feature outbreaks of deadly diseases and the efforts of scientists and medical professionals to contain them. However, entertainment movies can also educate the public about the importance and the impact those microorganisms have on our lives. A new publication in FEMS Microbiology Letters provides insights and examples to teach microbiology concepts to undergraduate students. Manuel Sanchez is a Microbiology professor at the Miguel Hernandez University of Elche. He's been using movies in class for many decades. He finds students can learn complex scientific concepts easily when integrated into a story. The expert has recently published a review in FEMS Microbiology Letters to show the relationship between movies and microbiology, from the fight against diseases such as AIDS or tuberculosis to the zombie apocalypse. "Maybe one day the Academy of Motion Picture Arts and Sciences will honor an Oscar award for microbes", writes Sanchez. According to the Internet Movie Database (IMDB), as of June 2023, there were 2,502 titles related to the keyword' virus', 184 related to 'bacteria', and 760 to 'infection'. For example, without viruses, we would not have such cinematic characters as the zombies that try to eat Brad Pitt and his family in "World War Z" or the cool vampires from the "Blade" saga. But are microbes villains, or are they heroes? Although microbes do much more good than harm in nature, this aspect is rarely represented on screen. Professor Sanchez explains that some film productions, especially recent ones, take great care in enrolling scientific advisors to have the most plausible and realistic scripts. However, in most occasions, that situation does not occur, so making a virtue out of necessity, movie goofs such as the scene from "Mission: Impossible II" where a flu virus infects a red blood cell, can be seen as an opportunity to explain the concept and conditions of viral host recognition to undergraduate students. Movies can be used in the classroom in two ways, depending on the time available. Students can watch the whole film as an external activity and then discuss its content in class. Another option is to use clips of selected scenes related to the subject to be addressed. For example, in minute 19 of "Dallas Buyers Club", a medical doctor (Jennifer Garner) explains to her AIDS patient (Matthew McConaughey) what is a double-blind clinical trial. This scene can be used as an introduction to a class about bioethics and/or drug development. Another example is the sequence at minute 74 from the movie "Panic in the Streets", which can be used to explain the 'One Health' concept, thanks to the following dialogue: Community? What community? Do you think you're living in the Middle Ages? Anybody that leaves here can be in any city in the country within 10 hours. I could leave here today and be in Africa tomorrow. And whatever disease I had would go with me… Then think of it when you're talking about communities! We're all in a community…the same one! Professor Sanchez's review can be helpful for teachers looking for such learning material. The paper is organized into three major sections, providing insights and examples of movies and TV/streaming series telling stories involving real diseases, others about the role of scientists, and feature films about the apocalyptic results of microbial infection. The first section is dedicated to the real infectious diseases represented on the screen. Commercial movies are better known to the general public than documentaries, so they could be used to explain the symptoms of the illness and other aspects, such as the care of the sick or the impact of the disease in a particular historical moment or in our current society. For example, in "The African Queen" (John Huston, 1951), Charlie, Humphrey Bogart's character, is bitten by a mosquito and is affected by malaria. Spoiler alert: he survives, unlike Giovanni de Medici in "Il mestiere delle armi" ("The Profession of Arms, Ermanno Olmi, 2001). A second section is dedicated to movies where the protagonists are the scientists and medical doctors who fight against microbial diseases. In this case, the main concepts to be explained are scientific methods and biocontainment measures. For example, "Outbreak" (Wolfgang Petersen, 1995) is so full of scientific mistakes that it's actually amusing to dissect. Also, the stereotype of the scientist has evolved from the solitary, dedicated hero of the 1930s to today's interdependent groups of highly technical researchers. Finally, the last part deals with the films in which microbes manage to defeat humanity, creating a dystopian world. Movies and series like "I Am Legend" (Danny Boyle, 2002), "28 Days Later", or "The Last of Us" (Neil Druckmann and Craig Mazin, 2023) are well known by the public and can be used to explain key concepts in epidemiology and disease transmission but also how to deal with highly stressful situations. Professor Sanchez is a microbiologist and science communicator. He has written several books regarding this subject and articles about microbiology in popular culture for The Conversation.

JOURNAL FEMS Microbiology Letters

DOI https://doi.org/10.1093/femsle/fnad129

ARTICLE TITLE Microbial pathogens in the movies

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JOURNAL

FEMS Microbiology Letters

DOI

10.1093/femsle/fnad129 

METHOD OF RESEARCH

Content analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Microbial pathogens in the movies