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Over 60 percent of infectious diseases began as zoonoses — spreading from animals to humans. What does this mean for preventing the next pandemic, and how can better animal health protect us all?
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00:00This silky bantam chicken is about to get a thorough check-up.
00:09But why exactly are scientists so interested in pets like her?
00:14What can we learn from chickens as a species?
00:18And what does any of this have to do with future pandemics?
00:21Let's check it out on this edition of DW's Science Show.
00:31Welcome to Tomorrow Today.
00:35In the course of the examination, I'd like to take samples.
00:38The first step, informed consent.
00:42Owner Marcel Czollik has to agree to the tests.
00:46We always do what works best for the animals and never use force.
00:49Sometimes that means we can't get a sample.
00:52If you're okay with all that, please tick yes.
00:58Then it's off to the chicken coop.
01:03All of the data from Marcel's three silky bantams will flow into the SHIP study.
01:08SHIP stands for Study of Health in Pomerania.
01:11More on this fascinating health project later.
01:14But first, why is Marcel taking part?
01:19We live close to nature here, surrounded by lots of trees, with lots of wild birds around
01:27that often eat the feed we give our chickens.
01:31So there's a lot of interaction with wildlife.
01:35And for us, of course, it's interesting to see, within the framework of this study,
01:40whether our pets might have picked up diseases from wildlife.
01:43Marcel doesn't need to bring his chickens to a clinic.
01:50The clinic has come to him.
01:52This way, the researchers can also see what kind of conditions the birds are kept in,
01:57like whether the coop is clean and light enough.
02:02Meet Astrid Puppe, the veterinarian examining the study participants' pets.
02:06In the SHIP One Health study, we're looking at the complex relationships between the health
02:15of pets, humans, and how does the environment actually have its impact on it.
02:23In focus are pathogens that can jump from animals to humans, called zoonoses.
02:29In the SHIP One Health study, we're also testing on avian influenza.
02:32It's a bit tricky.
02:34The virus is able to mutate and could jump species barriers, what we are mostly afraid of.
02:41There were cases in the UK where a SHIP was just infected, I think in the US or even here.
02:47I think milk cows showed no clinical science, but you found it in the milk.
02:53And so you really have to, yeah, it's good to keep track where the virus is and what is happening.
02:59Greifswald, a small city in northeastern Germany with a rich history.
03:07Home to a university.
03:10Since 1997, adults here have been regular subjects in the SHIP study,
03:15which is recognized by researchers internationally.
03:18It's the most thorough long-term study in the world, says Henry Völske.
03:26He's its director.
03:30We have the most comprehensive examination program, which has ever been performed in a population-based project.
03:38So people stay over 25 hours in our examination centers.
03:43And there are a lot of examinations, all non-invasive examinations, and our focus is on subclinical diseases.
03:52A subclinical disease causes only mild or no symptoms.
03:55Disorders which are actually not diseases but precursors.
03:58And we would like to observe the development from subclinical disorders to diseases.
04:05And one speciality of SHIP is that it does not focus on one specific disease or disease group,
04:12like cardiovascular disease or diabetes.
04:15We try to include all common diseases in one study.
04:20So it's a very complex project.
04:22This round, for the first time, includes pets.
04:30Or it will if they can be caught.
04:36The researchers want to know how having a pet can affect an owner's health.
04:43As well as how feeding and housing the animals in specific ways
04:48might help reduce the risk of pathogen transmission.
04:52And, yeah, I will take the swab in a minute, and then we will measure the temperature.
05:05After taking swab and fecal samples, the vet checks the chicken from head to toe.
05:11And I'm having a look at the feathers.
05:14And I will have a look at the eyes.
05:16She doesn't like it, but this looks really good and healthy.
05:23There are no lesions.
05:27Now I'm also looking at the ears.
05:31Yes, chickens have ears.
05:33They are just hidden under its feathers.
05:34So, is she looking for anything in particular?
05:42A specific pathogen?
05:44One pathogen we are especially looking for is Campylobacter yeyuni.
05:50That's the bacteria that causes fever and diarrhea in humans.
05:53It's often spread by undercooked poultry.
05:55The animals usually don't show any signs.
06:00Sometimes they have diarrhea, but not in all cases.
06:04If a human catches the germ, they can get really bad diarrhea and have to go to hospital.
06:11In most of the cases, it's not clear what the humans have.
06:14And this is also a point we want to bring awareness to that, yeah, maybe we could aim for better connections of human doctors and vets to actually connect and speak about the diseases going on.
06:29Because I recently had a patient who was hospitalized and didn't know what was happening.
06:35After three weeks, they did a test on the germ and later on, we found out that that was also from a chicken.
06:41One last blood sample, then the silky bantam chicken is done.
06:51For now, that is.
06:52We'll return to the second part of this story in a bit.
07:00In all likelihood, the COVID-19 pandemic began when a virus jumped from animals to humans.
07:06Though how exactly that happened isn't fully clear.
07:09Chickens, in any case, had nothing to do with it.
07:13Most researchers believe SARS-CoV-2 originated in bats.
07:17One scenario is that the virus made its way to humans in a crowded market where live wild animals were being sold.
07:24But there's also another theory.
07:27Some scientists say it's possible that the virus may have accidentally escaped from a high-security laboratory.
07:32And even today, research on coronaviruses continues, despite the risks.
07:38Across the globe, more and more laboratories are studying highly contagious viruses and experimenting with their mutations.
07:45At this Institute for Molecular Virology in Germany, Linda Brunot and her team use what's known as gain-of-function research.
07:56It speeds up mutations that viruses would normally develop on their own, either through selective breeding or by directly altering their genes.
08:05Scientists use it to learn how viruses become more infectious or dangerous, though in some cases, it can create real risks.
08:16Some of these experiments are completely harmless, like when we work with viruses that cause mild disease.
08:23We might add a green or red fluorescent marker protein to track how an infection spreads inside a cell.
08:33The goal is to understand how influenza viruses behave inside infected cells, and how they change over time.
08:41That kind of work is considered safe.
08:44But gain-of-function research can also involve making viruses spread more easily, or become more dangerous.
08:50So the question is, is that risk worth taking?
08:58Researchers never aim to make viruses more dangerous.
09:02Any work with pathogenic viruses is part of a broader experiment or project with a clear medical purpose.
09:09Like improving pandemic preparedness.
09:11We want to understand how threatening newly emerging viruses from animals, like birds, actually are.
09:17Virologists hope this research will help them better predict new diseases and future pandemics, and develop medicines.
09:27To do that, they sometimes modify viral genes to see how dangerous a pathogen might become.
09:34In 2012, virologist Ron Fouchier altered highly pathogenic H5N1 avian flu viruses, so they could spread through airborne droplets.
09:43The backlash came quickly.
09:46A New York Times editorial even described the work as an engineered doomsday.
09:53Years later, during the COVID-19 pandemic, the debate resurfaced, as people questioned whether SARS-CoV-2 might have emerged from risky gain-of-function research.
10:03In 2022, a group of scientists released a joint statement calling for an end to high-risk gain-of-function research on pandemic-capable viruses.
10:14Geneticist Günther Tyson also signed the statement.
10:17If I want to prove that a virus needs three mutations to become truly dangerous, I first have to create that dangerous virus.
10:29It's like messing around in my basement with wires, chemicals, batteries and timers, just to see whether my children could accidentally build a bomb.
10:39And in the process, I end up blowing my own hands off.
10:42The NGO Biosafety Now is calling for a global ban, or at least stricter regulation, of research involving pandemic-capable viruses.
10:57German bioengineer Valentin Brudel is an active member of the group.
11:01In the United States, Biosafety Now was involved in efforts that led to a temporary ban, at least on publicly funded gain-of-function research.
11:12The same happened in the UK.
11:14In Germany, unfortunately, that hasn't happened.
11:18I've repeatedly tried to reach out to politicians from the Greens, the Free Democrats and the Christian Democrats.
11:24In May 2025, a US presidential order sharply restricted high-risk biological research, effectively stopping several dangerous experiments.
11:37So, is research like this happening in Germany?
11:40We asked Berlin's Charité University Hospital if it conducts gain-of-function research.
11:48No one would speak on camera, but in writing, they stated,
11:53Such experiments are not conducted at the Charité's Institute of Virology.
12:00Yet the Charité website says that researchers work with dangerous MERS viruses and use gain-of-function techniques.
12:07And more questions remain.
12:11Can mutations really be predicted?
12:14And will scientists create drugs for diseases that don't exist yet?
12:19There's also a potential overlap between gain-of-function research and bioweapons work.
12:25But for scientists, this kind of work can be rewarding.
12:29Publishable results, funding, new professorships, and career advancement,
12:34as seen in the studies that made avian flu viruses more transmissible.
12:41They took five ferrets, infected one with a virus,
12:44then passed that virus on to the next one, and so forth.
12:48Technically, it wasn't complicated or costly.
12:52The study became highly cited, and research like this can really advance a career,
12:57even lead to a lifetime professorship.
13:02Millions poured into the field.
13:05There's a lot of money and many jobs tied to it.
13:09Even with strict safety rules, accidents still happen.
13:16In the U.S., from 2010 to 2014, biosafety level 3 and 4 labs,
13:23which handle the most dangerous pathogens,
13:26average two accidents a week, mostly due to human error.
13:34These accidents aren't always dramatic.
13:37But sometimes infected mice escape and are later found.
13:41Or mislabeled samples get shipped.
13:44A scientist might mistakenly send a sample that wasn't inactivated.
13:49Or a sample simply goes missing.
13:53So, should gain-of-function research be banned entirely?
13:57Or could a blanket ban actually cause more harm than good?
14:03You can't simply ban all gain-of-function research.
14:08You have to understand what that would mean.
14:13It would effectively ban 98% of meaningful research as well.
14:22At Münster's Molecular Virology Institute,
14:26researchers warn that broad restrictions on gain-of-function work
14:29could slow scientific progress.
14:34That's why evaluating gain-of-function studies is so challenging.
14:37You have to assess each one.
14:40The virus is used, the models applied,
14:42the resulting variants and their risk.
14:45A blanket ban isn't the answer.
14:52A new International Biosafety Authority,
14:55similar to the International Atomic Energy Agency
14:58under the United Nations,
15:00is one idea.
15:01That could help create the transparency
15:04that global research has been missing.
15:06Bacteria and viruses are constantly mutating out in nature.
15:12That's just what they do.
15:14But predicting which of these mutations
15:16might become dangerous to us is incredibly hard.
15:20Testing mutated pathogens on animals only gets us so far
15:23because the diseases they cause
15:25can look very different in humans.
15:27That's why researchers sometimes work with organoids,
15:32amazing miniature organs grown from human stem cells.
15:36So how does that actually work?
15:39This may look like a black spot,
15:47but it's actually a tiny heart.
15:49No bigger than the head of a pin,
15:51yet a major step forward for medical research.
15:56We've recently learned how to extract stem cells
16:00and how to make human-like tissue from them.
16:02That's revolutionizing science,
16:04everything from neurobiology to infection research.
16:09Organoids are miniature organs
16:11grown from human stem cells.
16:13At the Helmholtz Center for Infection Research in Germany,
16:17there are thousands of them,
16:18largely thanks to MOLI,
16:20an AI-based robot that works around the clock.
16:24Producing tiny hearts, lungs, and even brains,
16:27almost like an assembly line,
16:29MOLI can generate up to 30,000 organoids a month.
16:33Training the robot took time,
16:35but it's had a big payoff.
16:38It's freed up a lot of capacity for other work.
16:41The pipetting the robot does
16:43is very repetitive and quite strenuous.
16:46My arms get tired after a while,
16:48but for the robot it's no big deal,
16:50even with only one arm.
16:53That lets us produce far more organoids per day,
16:56which we can then use for real infection experiments.
16:59The team uses these organoids
17:02for early-stage drug development.
17:04From thousands of potential compounds
17:06stored in containers like these,
17:09they identify the most promising candidates.
17:12The organoids are infected with viruses
17:14and exposed to different substances
17:16in varying doses.
17:18Researchers observe how the miniature organs respond,
17:21determining which compounds are effective.
17:24But this approach also has its limits.
17:26With an organoid,
17:30I can tell whether my active ingredient works,
17:32whether it protects the cell or not.
17:35But I can't test whether it reaches its target in the body,
17:38since it still has to be taken orally or injected.
17:42I also can't see if it might help the heart,
17:45but harm the kidneys.
17:46But the lab-grown tissues have no immune system
17:52and don't interact with other organs.
17:54So complex processes still have to be studied
17:57in a living body.
18:00We still have to carry out animal experiments
18:02for certain things.
18:04For example,
18:04more complex interactions,
18:06like an infection that affects not only one tissue,
18:09but the entire body.
18:10COVID is a good example.
18:12So this doesn't replace animal testing,
18:15but using these organoids
18:17does allow us to develop better,
18:19much more precise drugs.
18:20And that, of course,
18:21makes it possible to do less animal testing.
18:25The team hopes to make their organoids
18:28available to other projects,
18:30reducing the need for animal experiments
18:32and helping ensure cages like these
18:34stay empty more often.
18:38More than 60% of all known infectious diseases
18:42are zoonoses,
18:43illnesses that spread from animals to humans.
18:46And the closer humans and animals live together,
18:49the greater the chances that a pathogen
18:51makes that leap.
18:53In Germany,
18:54the Friedrich Löffler Institute
18:55studies the health of livestock
18:57like sheep, chickens, ducks, cows and pigs.
19:00But they're also interested
19:02in the welfare of our house pets,
19:05the companions we share our homes and lives with.
19:11At the Friedrich Löffler Institute,
19:14we move to the second part of our story
19:16on animals and human health,
19:18with scientists hard at work in the lab.
19:24Before analysis,
19:25samples have to be prepared.
19:27And that's not always exactly a fun job.
19:29This one is dog poop.
19:34But the researchers' curiosity
19:36is stronger than their disgust.
19:42Under the microscope,
19:43a different sample proves
19:44to be loaded with parasites.
19:48This one is sporulated,
19:50so it's infectious.
19:52The sample came from a cat.
19:54They might be adorable,
19:55but our fairy-feline friends
19:57can transmit pathogens.
19:59An infected cat will shed millions
20:01into the environment
20:02in those sort of 10 to 14 days
20:04that they're infectious.
20:05Yeah.
20:06The researchers have identified
20:08the pathogen that causes toxoplasmosis,
20:11Toxoplasma gondii.
20:12It's a parasite mainly spread by cats.
20:17The WHO estimates a third
20:18of the global population
20:20is infected with it.
20:22In humans,
20:23often it's an asymptomatic infection,
20:25meaning that we really don't see
20:26the effects of the infection.
20:28But where the real concern is
20:30is that when pregnant ladies
20:31become infected,
20:33depending on what stage
20:34of gestation that they're at,
20:36it can have some pretty
20:37serious consequences
20:39on the fetus.
20:40So that's where our real concern
20:42around Toxoplasma gondii
20:44comes from.
20:46This is Johanna Dubz-Bergmann,
20:48an epidemiologist
20:49who specializes in parasites.
20:54How can infections
20:55like Toxoplasma gondii
20:57be prevented?
20:59The researchers
21:00don't just publish their findings,
21:02they also provide information
21:03and tips for pet owners.
21:06The goal?
21:07To stop zoonoses.
21:09Of all our emerging
21:12infectious diseases
21:13that we're seeing currently,
21:15about 75% of them
21:16are coming from
21:17an animal reservoir.
21:18They're zoonotic diseases,
21:19which means,
21:20really thinking of it
21:21from a numbers perspective,
21:23there is a good chance
21:23that the next pandemic
21:25may come from
21:26an animal reservoir
21:26or an infection
21:28or a disease
21:28that is circling
21:29animals at the moment
21:30and is able to cross
21:31that species barrier
21:32into humans.
21:33So that is where
21:34the idea of One Health
21:35comes in,
21:36which is saying
21:36we can no longer look
21:38at these infectious diseases
21:39in isolation.
21:40We need to look at them
21:42on the more holistic area
21:44to understand
21:44where can we have
21:46effective interventions
21:47to try and protect
21:48the health of humans
21:49through protecting
21:50the health of animals,
21:52you know,
21:52via protecting
21:53our environment as well,
21:54because each of those elements
21:55will work together
21:56to allow something
21:58to potentially cross
21:59the species barrier
22:00and become another pandemic
22:03or something.
22:06Back to our silky Bantams.
22:09The check-up took
22:10about an hour.
22:12In total,
22:121,100 pets
22:14were examined
22:15during the study.
22:16Preventing outbreaks
22:17is hard work
22:18and if efforts are successful,
22:20the success goes unnoticed.
22:22For Astrid Puppe,
22:28two things have become
22:29really clear.
22:30First,
22:31pet owners need
22:32more information
22:33about vaccinations,
22:35parasites
22:35and deworming.
22:37And second,
22:38We have a lot of
22:40chicken owners
22:41living in the city
22:43and just housing
22:44their chicken
22:44in the backyard.
22:46But concerning
22:47an outbreak,
22:48this is of course
22:49really interesting
22:49because you would never
22:51actually expect
22:52an outbreak
22:52of avian influenza
22:53just within the city,
22:55more on the countryside.
22:57And in this case,
22:58that was really interesting
23:00for me in the study
23:01to see where chicken
23:02are kept and held.
23:04And we also give feedback
23:06to the veterinary authority
23:07and from my part of view,
23:11there could be an improvement
23:12to actually monitor
23:13these chicken owners
23:14more that live
23:15within the city.
23:16The vet is satisfied
23:20with how the silky
23:21Bantam check-up went.
23:23Look, an egg.
23:25I even found an egg.
23:31Time for a preliminary
23:32assessment.
23:33The animals look good,
23:35although the lab
23:36still has to analyze
23:37the samples.
23:39So in general,
23:40all street chickens
23:41are bright and healthy.
23:43If I have a specific finding,
23:45I will call the owner
23:47if we don't find
23:49anything specific.
23:51He only gets the results
23:53per post in a few weeks.
24:01Back in the coop,
24:02life goes on.
24:05Yeah, yeah,
24:06we are leaving now.
24:08Goodbye, chickens.
24:09And while we're at it,
24:19we've got an answer
24:20to a very important question.
24:24Which came first,
24:25the chicken or the egg?
24:28For the longest time,
24:29science was in favor
24:30of the egg,
24:31but researchers
24:32aren't so sure anymore.
24:34How come?
24:35If we talk about evolution,
24:36chickens evolved from
24:38other birds,
24:39which evolved from
24:40dinosaurs.
24:41And guess what?
24:42Those dinosaurs laid eggs.
24:44We have proof of that
24:45in the form of
24:46fossilized dinosaur eggs.
24:48So yes,
24:49the first chicken
24:50hatched from an egg.
24:52Case closed.
24:53Or not?
24:54Because when you think about it,
24:56the question actually is
24:57when and how did eggs evolve?
24:59And was it before
25:01or after life birth?
25:02Which would be the other option
25:04for bringing your offspring
25:05into the world?
25:06And here it gets tricky.
25:08The established theory
25:09is that eggs were first
25:11and were a super important
25:12adaptation that allowed
25:13our early ancestors
25:14to make the move
25:15from water to land.
25:18But newer fossil finds
25:19and research suggest
25:20that conventional eggs
25:22might,
25:22over several steps,
25:24have evolved from life birth.
25:26So how does this help us
25:28with the chicken and egg conundrum?
25:30Yes,
25:30chickens are evolutionarily
25:32younger than eggs.
25:34But when and how eggs evolved,
25:36we don't really know yet.
25:37So it might be
25:38that the early ancestors
25:40of dinosaurs and chickens
25:41didn't lay eggs
25:42but gave birth.
25:44And in that case,
25:45you could argue
25:46that the chicken
25:47kind of came before the egg.
25:49And that's all for now.
25:54Thanks for watching.
25:55See you next time
25:56on Tomorrow Today,
25:58your science show on DW.
26:00.
26:03.
26:16.
26:25.
26:28.
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