Riems — an island in
the Bay of Greifswald in northeast Germany. It measures just
1-point-3 kilometers long and three hundred meters wide — and is home to the oldest
virological research institute in the world. The Friedrich Loeffler Institute. The FLI is unique in Europe and one of just three
facilities world-wide where research is carried
out on large animals at the highest
level of biosecurity. 80 different animal diseases
are under investigation here, including pathogens requiring the strictest level
of containment. And those deadly
germs cannot be allowed to escape from the lab
under any circumstances. Climate change and globalization are among the factors driving
the advance of diseases, such as the West Nile
Virus spread by mosquitoes, and Borna Disease. Researchers work in
laboratories and animals sheds that are hermetically
sealed off from the outdoors. Working under the highest
biosafety conditions, BSL-4, their aim is to protect
animals from deadly diseases. They need to strike
a delicate balance between immediate animal welfare and the long-term
necessities of research. But the impact of diseases
on humans is, of course, also an issue. That’s why the experts
are doing all they can to gain insights into
the ways — or vectors — via which the pathogens spread. It’s a battle against
an invisible enemy as well as a race against time. In October 2020 Sandra
Blome, laboratory supervisor at the FLI’s Institute
of Diagnostic Virology, received a package with
extremely hazardous contents. The delivery had to be
handled with the utmost caution. It contained tissue samples
from a dead wild boar. It was possible the animal
had died from a plague that has recently been
spreading in Germany. The ominous news first
came in September 2020. The carcass of a wild boar was
discovered to the east of Berlin, close to the Polish border. The animal seemed to
have died of a disease that infects domestic
and wild pigs — and is nearly always fatal. The news came as a
shock, but not as a surprise. It’s a virus that has
been rampaging in Eastern Europe for
years, including in Poland. Tens of thousands of
domestic and wild pigs had already died from it. The virus was African
Swine Fever, or ASF. For humans: it’s not a threat. In Africa, ASF is transmitted
by ticks from warthogs and bush pigs to domestic pigs. The animals become
infected through direct contact, mainly via the blood
of infected members of the same species. Viruses of this kind are
comprised only of a protein shell and their genetic material
— so from DNA or RNA. They aren’t able to
reproduce on their own. To do that, they need a
living host — such as a pig. The pathogen penetrates
what is called the “host cell”. Once inside, the
genetic material then programs the cell to
produce more, new viruses. The cell dies and releases
thousands of pathogens that go in search of new host cells. Frequently, the animal
can ward off the invader and only becomes
slightly ill — if at all. But sometimes, the
virus encounters a host whose immune system is
overwhelmed by the virus. The disease is one
among many in Africa that might make warthogs
and bush pigs sick — but not fatally so. But Eurasian pigs have
yet to adapt to the pathogen. If an animal becomes infected, it will die in
practically every case. The new tissue sample
from the dead wild boar in Germany was
analyzed in the lab. If it turned out to be
positive for the virus, that meant the disease was
spreading further westward. And the sample was positive. The disease was on the march. The virus’s journey to
Europe began in 2007. A freighter from East Africa
was heading for Georgia. In the port of Poti, it
unloaded meat scraps at a rubbish dump. Soon, more and more
domestic pigs in the region were becoming seriously sick. And a short time later, wild boars — here marked in blue —
fell ill as well. Since then the plague
has spread relentlessly — via Russia and the Baltic
states toward Western Europe. In Germany, alarm bells
started ringing in 2019, when the first cases were
detected in western Poland. To prevent the virus
spreading further, the authorities set
up electric fencing near the border to
keep out wild boars. But by 2018, the virus had
already reached Belgium — after seemingly
“jumping” over Germany. And even today,
France is disease-free. Humans likely made a
contribution to the pathogen skipping certain
countries in Europe. Researchers suspect that
the virus spreads in food — because the ASF
is particularly stable. Even in processed pork, it can
remain infectious for months. But there is still
no definitive proof. Nevertheless, it’s highly
probable the disease reached Belgium in just that way — via left-over meat
transported by humans. Wild boars are omnivorous — and don’t turn their
snouts up at meaty scraps. And there was a
conspicuously higher rate of outbreaks of ASF along
transregional routes. In the end, the
precautions failed to help. African Swine Fever
reached the eastern German states of Brandenburg
and Saxony in September ... and October 2020. Up to now, the
disease has only spread among wild boar in Germany, but the risk is great that
the virus will eventually infect hog fattening farms. An outbreak would be an
economic disaster for Germany, which is the world’s third
largest producer of pork. But how can the further
spread of ASF be prevented? Because of a warm winter and
an increase in available fodder, the numbers of wild boar in
Europe have mushroomed. There are more than
90 thousand of them in Brandenburg alone. Authorities there have been
relying on a radical strategy to stem the tide of wild boars —
via culling ... and using
unconventional methods. By the end of April 2020, ASF had been raging for months on the Polish side of the river Oder — which infected animals
were able to cross without too much trouble. Egbert Gleich is a wildlife biologist who works for the local
authorities in Brandenburg. He’s also an expert in very
special “hunting” techniques. The method he uses is ideally suited to rapidly decimating
wild boar populations — like the one overrunning
the Oder Valley. He’s one of the few specialists who hunt with cage traps. Trapping is controversial. But criticism takes a back seat — given the spread of the plague and the unmatched
effectiveness of the method. Here in these areas, we
want to get the wild boar population down as low as possible. So we’ve got to take
measures that for now essentially mean the elimination of the wild boar population. Thinning out the wild
boar population is vital in the bid to slow the
spread of the virus. But ultimately, ASF can
only really be stopped by a vaccine for wild
boars and domestic pigs. There have been years of
research, but so far in vain. The virus that causes
African Swine Fever is a tough and tricky foe. ASF is a very large virus with a very, very, complex structure. The virus is
— as I always tell students — a battleship. It’s loaded with factors
that allow it to alter the immune system
in favor of the virus. That makes it all extremely difficult. So ... Sandra Blome and her team are investing their
hopes in a new strategy. They’re using
genetically altered viruses. We’ve taken certain characteristics from the viruses we’re
using as vaccine candidates. For one, they outwit
the immune system, making it difficult for
the immune system to recognize the virus. Then there are “virulence
factors”, which are — or we hope they are — what ultimately
makes the animal sick. The pathogen that
causes ASF has tools that prevent the immune
system from recognizing it. They’re called immune modulators, and allow the virus to
reproduce unhindered. To create a vaccine, the researchers are using
genetically altered viruses with the help of this “camouflage”. The result —
after just a short time, the immune defenses
recognized the altered viruses. They block multiplication and form immune
cells and anti-bodies. When the body is then
confronted with genuine pathogens, the immune system has
learned to dodge the ruse and strike back. The potential vaccine has proved to be very promising in the lab. The next step:
trials on live pigs. It’s the only way Sandra
Blome and her team can find out if the vaccine
really does protect animals from the virus. With camera teams not
allowed in the bio-secure lab, the scientists filmed the
experiments themselves. Half of the pigs were injected with the genetically altered virus. A control group was
left unvaccinated. Three weeks later, the
researchers would infect the animals with the genuine and up to now deadly virus. Egbert Gleich has been
waiting for two hours to sight wild boars in
the Lower Oder Valley. And suddenly, they appear. The morsels of grain have lured
eight specimens into the trap. The young animals
still don’t suspect a thing. Now Egbert Gleich has to move fast, so that their suffering
is kept to a minimum. It takes him less than two
minutes to get from the car to the trap. A minute later the animals are dead. This is not “hunting.”
It’s execution. But the wild boars’ speedy demise could save thousands
of their taxonomic cousins from an otherwise agonizing
death caused by ASF. Egbert Gleich and a
colleague now check whether the wild boars
that have been killed are indeed carrying the
African Swine Fever virus. They draw blood
from the cadavers and take the samples to the
local veterinary inspection office. What counts for the
researchers, however, is the appearance
of the internal organs. They indicate whether
the animal was sick or not. The spleen is totally
flat, with normal coloring. If swollen, the color
would tend to be darker. And here we have the kidneys. Usually they’re light-colored, and there would be loads
of little spots on them. So there aren’t any
noticeable signs in this animal. Back at the institute on Riems, three weeks have gone by ... Sandra Blome and her
team are getting ready to infect pigs, who’ve
been vaccinated once: with the real, deadly virus. The virus kills almost all
unprotected domestic hogs — after days of torment
from high fever, diarrhea, breathing difficulties
and hemorrhaging. Most of the vaccinated
pigs show no symptoms — while the unvaccinated
animals in the control group become severely ill. Sandra Blome has also
tested vaccines on wild boars. But another strategy
is needed to prevent the spread of the virus in the wild. You can’t really tell wild boars that they’ve got an
appointment to be vaccinated, so we always need a vaccine that can be administered orally. We need a safe live virus vaccine that is nevertheless effective, so the genetically altered organisms need to be tested
for a long time before we can really release
them in the field. The researchers say they’ll
have a functioning vaccine by 2022 at the earliest. The history of “plague
island” is closely linked to another devastating
animal disease. At the end of the 19th century, Germany’s farmyards were haunted by a devastating specter. Hundreds of thousands of
cattle and hogs were killed by a mysterious sickness —
foot and mouth disease. The cause was unknown. In 1897, the then Prussian
government commissioned virologist Friedrich Loeffler
to research the disease. Loeffler set up sheds in two arches underneath Berlin’s elevated railway and began his experiments. Loeffler was a pupil of
the famous bacteriologist, Robert Koch. And at first, he and his colleagues were searching for bacteria. But they soon observed
that the usual filters failed to stop the pathogen, which therefore had to be
much smaller than bacteria. The scientists had discovered a new, previously unknown type of microbes — viruses. Loeffler was aiming to find a
cure for foot and mouth disease. He continued his
experiments in Greifswald at a farm on the
city’s outskirts. But the disease repeatedly
spread to neighboring farms. The government stopped the research. Loeffler needed a place where he could carry out
his experiments without risk, and found it on the island of Riems, off the German Baltic coast. In 1910, he set up
laboratory buildings and barns. The new institute was cordoned off, and could only be reached by boat. Friedrich Loeffler had
founded the world’s first virological research institute. He died in 1915. But work on Riems
continued after his death — and really gained
momentum in the 1920s, with new labs, animal
sheds, living quarters and entertainment facilities
for the institute’s workers. As in the past, foot
and mouth disease was the primary
focus of research. But they were
joined in in the 1930s by other viral
livestock diseases, such as avian — or bird —
flu and classic swine fever. But the first vaccine against
foot and mouth disease wasn’t finalized until
the end of the 1930s. Nevertheless, there
were repeated outbreaks of the disease after
the Second World War. In 1950, East Germany
became the first country to require vaccination
against the viral illness. There haven’t been
any cases in Germany for more than three decades. In neighboring France, the last
outbreaks were seen in 2001. Today, on Riems, the “plague island,” researchers are also examining viruses hailing from other
parts of the world — because in the meantime, the pathogens have
become globetrotters. Doctoral candidate Lorenz Ulrich is setting up an experiment
that needs to take place at the highest biosecurity level, because this virus is
active and highly infectious. The new coronavirus pandemic has cost the lives
of millions of people — with further millions infected. SARS-CoV-2 — an RNA virus
from the coronavirus family. It’s believed to have originally
infected a species of bats and “jumped” to humans
via an intermediate host. But can the disease
travel in reverse — from human to animal? We know that it infects
humans primarily. We know that it emerged
from an animal source, probably from bats, and
maybe came to infect humans via an intermediate animal host. But we don’t know if
other species of animals can become infected. So can the virus jump
from humans to animals? In the meantime, it’s known
this is possible with cats. From experimental studies we know that household cats
can be infected by strays. But we’re waiting for more field data. At the moment, we’re
examining the statistical distribution of feline samples in order to get an
idea of how many cats really have become infected. What percentage
of them have actually been exposed to SARS-CoV-2? But what about livestock — with hogs or cattle for example? We want to know if
this virus can infect pigs, chickens and cattle. If the virus can
spread in the animal, then we would have a new reservoir, and in some cases
a very large reservoir. So there might again be the threat of infection from
animal to human. There are almost a
billion cattle in the world — many of them in close
contact with humans. Can the animals catch
the Sars-CoV-2 virus? Researchers at the
Friedrich Loeffler Institute have been looking at
how great the risk is. Experiments on
cattle are conducted in a high-security
area of the institute. For safety reasons, filming is only allowed
until the researchers go through the
decontamination station. After that, the scientists record
their experiments themselves. There are nine test cattle
in the high-security shed. Six of them are set to be infected. The virologists want to
find out if the pathogen will multiply. Three additional calves
serve as contact animals, to see if the virus can move
from animal to the other. The researchers
administer the virus to the animals’ nasal mucosa as humanely as possible. After a six-day incubation
period the researchers will test the animals to determine whether the virus has multiplied, and if the cattle are
already exhibiting symptoms. Just how serious
the effects of the virus can be on animals is
shown by the example of the white mink. It’s been proved that
some have been infected via contact with humans. Scientists have also
discovered that the virus can mutate once it is in the mink — and then spread
back to humans again. At least twelve people in
Denmark became infected with this new variant of the virus. Millions of the fur-farm animals then had to be culled in Denmark. Meanwhile, back at the
bio-security facility in Germany, after six days the
cattle aren’t showing any apparent
symptoms of the disease. The researchers
are now interested in the viral load
in tissue samples. Have the pathogens reproduced? They also take blood
samples to detect antibodies. Their presence would indicate that the immune system
had been activated. Everything is painstakingly
disinfected after the testing - to ensure none of
the pathogens escape. Over in the lab, other researchers are tracking the virus genome. That would also indicate whether the virus has multiplied in an infected animal. And by checking antibodies,
they are able to determine if the animal had
contact with the virus even after a longer time period — and also when the
pathogen is no longer present. In the end the results
showed that the virus did multiply in the cattle’s bodies — but only in two of the
six that were infected. The scientists also
detected antibodies, although the infected animals did not spread the pathogen. Plagues like the
coronavirus pandemic are by no means
uncontrollable natural events. On the contrary: humans themselves
often create ideal conditions for the spread of viruses
from animals to humans by intervening in natural processes. Studies show that the
destruction of habitats and the loss of global biodiversity are decisive forces driving the
transmission of new pathogens. Human encroachment
on previously untouched ecosystems and the constantly growing, global movement of people
and goods are a toxic mix. They contribute
significantly to diseases spreading further and
further and ever more rapidly. Seventy percent of all
new infectious diseases come from animals. A majority of them are carried
and transmitted by viruses. Mandy Schäfer and Helge Kampen are hunting mosquitoes. Now, at the beginning of fall, as the mosquito
season comes to an end, the entomologists have
trapped a few of the insect pests. There are similar traps in
35 places across Germany. The scientists from
Riems want to find out how the mosquito population
is changing in the country. For some time now, they’ve been seeing
a growing number of mosquitos that didn’t
used to be present here. Over the last ten years, the two entomologists
have identified six of these invasive species: including the Asian bush mosquito, the Korean bush mosquito and the Asian tiger mosquito. Among the viruses carried
by the Asian tiger mosquito are Dengue, chickungunya, and zika — plus another pathogen that most people
will not have heard of. In early autumn 2020, Berlin was getting ready to face the second
coronavirus wave. With attention focused
on the pandemic, another development
went largely unnoticed. A man was diagnosed
with a disease that likewise came
from a new virus. The case was the
seventh in Germany. Yet the scientists estimate
that the real number is about 100 times higher. The disease only becomes severe — resulting in fever,
encephalitis, and even death — in only some of those infected. The disease is caused by
the West Nile Virus or WNV. It’s generally spread by mosquitoes. WNV originated in Africa,
but in recent years it’s spread from southern to central Europe — probably and first and
foremost by migratory birds. Previously in Germany, those infected were just travelers who came back from tropical regions
with the disease. But this time it’s different. All of the patients picked
up the disease in Germany. How did a tropical pathogen like WNV become settled in Germany? And is there a connection
to the Asian tiger mosquito? In the insectarium at the
Friedrich Loeffler Institute, new generations of
the Asian tiger mosquito are being bred for research purposes. To ensure that they grow and thrive — and above all
reproduce in big numbers — entomologist Mandy
Schäfer feeds them with fresh animal blood. The researchers on Riems want to improve
their understanding of this species of mosquito. The insects from the tropics are currently settling in Germany, as they’ve been doing for
years in southern France. Thanks to the increasingly
warm summers, the Asian tiger mosquito is feeling increasingly at home here, too. Above all in southern Germany, where stable populations
have already formed. But West Nile fever broke out in the northeast of the country ... in 2018 in animals and
then in the following two years in people for the first time
— marked here in orange. But there aren’t actually any Asian tiger mosquito
populations up here. Research showed that by contrast, another species of mosquito
was spreading the virus — the common house mosquito. So how was it able to
transmit a “foreign” virus? The solution to the
apparent enigma was that the West Nile Virus isn’t foreign to the
common house mosquito — because this species
came from Africa too. Except that in Europe, virus and insect hadn’t
yet had the chance to meet. And that’s precisely
what’s happening now, driven by warming temperatures. Plus, it’s merely a question of time until the other viruses
carried by mosquitoes begin to spread as well. In October 2019 in
Bavaria, a girl we’ll call “Lisa” was on her way to sports practice. The thirteen-year-old
had had a bad headache since the morning. Lisa was a good archer — but that day, things
were different. She was unable to
focus on the target, and was experiencing
double vision. It was clear something
was very wrong, and the coach sent the girl home. On the way home, the
headache got worse. Then Lisa collapsed
and lost consciousness. The doctors diagnosed
acute encephalitis. Lisa never regained consciousness. She died after two days in a coma. Lisa’s death was one of several that had gone unexplained
after running a similar course — sudden encephalitis,
followed by coma and death. The cause remained unknown. But there IS a virus that
has similar symptoms of brain dysfunction. It’s called Bornavirus or B-o-D-V-1. It’s long been known that
the disease infects horses — but for humans, Borna disease was thought to pose no threat. Researchers know that the
actual reservoir of infection is another, smaller animal
— the bicolored shrew. In Germany, shrews
that carry the virus can be found in the
states of Bavaria, Thuringia and Brandenburg. That’s also where the
deaths have been occurring. In France, for example,
there have been no signs of it in either animals or people. Researchers on Riems
have been looking for clues together with
virologist Martin Beer. And they’ve managed to
identify the Borna disease virus in tissue samples from
the fourteen people who’ve died, including young Lisa. Once it’s reached the human brain, it becomes a deadly virus. That’s when those
who’ve been infected have about a 90
percent chance of dying. The good news is that
the event of actually reaching the brain
is evidently very rare. This is the brain of a
bicolored shrew from Bavaria. If it tests positive for the virus, this is where the researchers
would expect to find it. They want to find
out how the pathogen jumps from the shrews to humans. Has the virus changed genetically? The genetic material
from the virus in the shrew is compared with tissue
from the human victims — using a new, more
comprehensive method. It turns out that the
bicolored shrew was positive — and, more importantly,
that the virus type is the same one that
led to the death of Lisa. That said, however ... We still don’t know what
the precise route was — for example if there
was direct contact, because they picked up a
dead shrew in the garden or the cat brought one in ... Another theory would be
that the bicolored shrew excretes the virus,
including in its urine, and that people
were then infected by eating freshly
picked lettuce or herbs, or maybe hanging around
outside in the garden. We’ve also seen a
pattern in the patients — that they actually did
do outdoor activities and lived in very rural areas. But that’s no reason
to lock yourself indoors. We also know that the
virus stays in specific areas — the precise dispersal area
of the bicolored shrew ... So it’s a very deadly
virus that is apparently only rarely transferred
and then not very easily. Unlike Borna disease, the pathogens for African Swine
Fever can’t jump to humans. Nevertheless, the disease
threatens the livelihoods of many people —
and the lives of millions of pigs. The Friedrich Loeffler Institute has teamed up with the
Bavarian Forest National Park to gain more information
on how the virus spreads. Carolina Probst and Marco Heurich are looking for clues
that would indicate how long ASF has
been present in a region and how far it may have spread. They’ve picked various
sites in the national park for their experiment — places
that are as far as possible from streets and hiking trails. This dead boar is one of several being used for their field study. We suspect that
wild boar carcasses play a very central
role in the epidemiology of this animal plague. And we’re using
these experiments to try to find out how the
process of decay occurs. That will show us
how long the ASF virus can remain alive in a carcass. How quickly does a
dead wild boar decompose in different surroundings — on dry or moist earth, for example. And: how long is it
a source of infection? We know that
unlike other viruses, this one stays stable out in
nature for a very long time — perhaps even for months. The virus is present
in large amounts, in tissue and especially
in the blood and muscles. These are places
well-supplied with blood. Also the spleen, for example, and other internal organs. A camera documents
the decay of the wild boar. It takes one image a day ... After seven days of warm weather, the carcass is already in
an advanced state of decay — thanks to swarms of
insects and their maggots. One key finding is that after
several weeks have passed, only one specific part of the cadaver remains dangerous
as a source of infection. The bones are our big
worry, especially the ribs. And preceding studies
show that the ribs are very appetizing
for other wild boar, especially for young animals because their bones
are still growing. And that’s our biggest concern: that ASF will remain in
the wild boar population for a very long period
in an affected region. It will till take months for
the research to be complete. But one thing is already clear — wild boar carcasses
are viral time bombs. And in order to stem the
spread of African Swine Fever, it’s necessary to defuse
them as fast as possible. That’s easier said than done — because the dead
boars often lie undetected for weeks or months
in the undergrowth. This is the site of an outbreak in the Brandenburg region
of northeast Germany. Teams working with dogs are trying to find wild
boar that have died of ASF. They also have high-tech
tools at their disposal. Former soldier Steffen Franzeck is using a drone in an attempt to find wild boar in the
forest — dead or alive. The drone is fitted
with a normal camera, and a thermal imaging device. Look, there’s something
lying back there in the corner. Yep, and it’s still warm, too.
Eleven degrees. They are indeed boars —
albeit still very much alive. In normal mode, you
can often see wild boars. There’s one right up there. Wildlife expert Julian
Dorsch is also in the team. There are three lying there. The camera images
show that the animals are apparently still healthy. But the thermal imaging
device can find cadavers as well. Even days after an animal has died, the body can emit extremely high decomposition temperatures. It’s very likely the animal
died of African Swine Fever — and is as such an infection reservoir that would’ve remained
hidden for weeks or months without the help of the drone. The researchers at the
virological institute on Riems will have plenty of work
to do in the years to come. Because viruses have long
since become global agents. On “Plague Island” and in the field, the scientists are doing all they can to beat them at their own game.
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