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Coronavirus Pandemic Linked to Destruction of Wildlife and World's Ecosystems

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A farmer shifts through soil after a burn session in China's Xishuangbanna region, once home to tropical rain forests. Ryan Pyle / Corbis / Getty Images

By Charli Shield

After the novel coronavirus broke out in Wuhan, China in late December 2019, it didn't take long for conspiracy theorists to claim it was manufactured in a nearby lab.


Scientific consensus, on the other hand, is that the virus — SARS-CoV-2 — is a zoonotic disease that jumped from animal to human. It most likely originated in a bat, possibly before passing through another mammal.

While the virus was certainly not engineered in a laboratory, this doesn't mean we haven't played a role in the current pandemic. Human impingement on natural habitats, biodiversity loss and ecosystem degradation are making virus spillover events much more likely, a major new study from scientists in Australia and the US has found.

The number of emerging infectious disease outbreaks has more than tripled every decade since the 1980s. More than two thirds of these diseases originate in animals, and about 70% of those come from wild animals. Many of the infectious diseases we're familiar with — Ebola, HIV, swine and avian flu — are zoonotic.

Aided by a hyper-connected global population, SARS-CoV-2 and the disease it causes, COVID-19, has also demonstrated how quickly modern outbreaks can become pandemics.

While the speed at which COVID-19 has spread across the world has shocked many, scientists have long been warning of such a pandemic.

By disrupting ecosystems, we have created the conditions that allow animal viruses to cross over into human populations, says Joachim Spangenberg, ecologist and vice-president of the Sustainable Europe Research Institute.

"We are creating this situation, not the animals," Spangenberg told DW.

Deforestation, habitat encroachment

As people move further into the territories of wild animals to clear forests, raise livestock, hunt and extract resources, we are increasingly exposed to the pathogens that normally never leave these places and the bodies they inhabit.

"We're getting closer and closer to wild animals," says Yan Xiang, professor of virology at the University of Texas Health Science Center, "and that brings us into contact with these viruses."

"As you increase human population density and increase encroachment onto natural habitats, not just by people but by our domesticated animals, you're increasing the rolls on the die," David Hayman, professor of infectious disease ecology at Massey University in New Zealand, told DW.

But, as well as increasing the likelihood of transfer, ecosystem disruption also has an impact on how many viruses exist in the wild and how they behave.

In the last century, tropical forests, home to around two thirds of the world's living organisms, have been halved. This profound loss of habitat has ripple effects throughout the entire ecosystem, including on the "parts we tend to forget — infections," says Hayman.

In some cases, scientists have observed that when animals at the top of the food chain disappear, the animals at the bottom of the food chain, like rats and mice that carry more pathogens, tend to fill that space.

"It's not just about how many species we have in an ecosystem," says Alice Latinne at the Wildlife Conservation Society, "it's about which species."

"Each species plays a different role in the ecosystem and sometimes, if you just replace one species with another, this can have a huge impact in terms of disease risk. And sometimes we can't predict it," she told DW.

Habitat changes can also force animals — and their pathogens — to go elsewhere, including areas populated by people.

Latinne draws on the example of the emergence of Nipah virus in Malaysia in the late 1990s, where deforestation drove fruit bats from their forest habitat to mango trees on pig farms. Bats often carry pathogens that don't bother them, but in this case when the pigs came into contact with bat droppings and saliva, they became infected. The pigs then went on to infect farmers.

Evidence linking disruption of ecosystems to increased risk of novel infection transfer is why, Spangenberg says, experts talk about the importance of the "One Health" concept; the idea that the health of animals, the ecosystem and humans are all interlinked, and when one is out of balance, others follow suit.

Wildlife trade

So-called "wet markets" selling produce, meat and live animals provide another incubator for the emergence of infectious disease. Scientists believe there's a strong possibility SARS-CoV-2 emerged at a wet market in Wuhan, China.

Cramming stressed, sick animals into cages together is, in many ways, the "perfect setting" to incubate new pathogens, Spangenberg says, and "an excellent way to transfer diseases from one species to another." For that reason, many scientists, including Spangenberg, say the world needs, at the very least, to introduce strict regulations for live animal markets.

That's the message from Elizabeth Maruma Mrema, the United Nations' biodiversity chief, who has called for a global ban on wildlife markets.

But as Mrema also pointed out, millions of people — particularly in low-income communities — rely on the food and income sources these markets provide.

That's part of what makes solutions to preventing disease outbreak complex, according to Hayman. Animal exploitation is one part of it, he says. But "poverty, access to jobs, how people are treated in remote areas, the way people engage with food" also contribute to conditions that lead to spillovers.

Even just on an economic level, Latinne believes, "we will be forced to change — because the cost of disease emergence and spillover from wildlife will be much higher than the economic benefit of our exploitation of the environment."

"We are part of nature — we're part of the ecosystem where our health is linked to the health of wildlife, the health of livestock and the health of the environment," Latinne says. "We have to find a better way to live together safely."

Reposted with permission from Deutsche Welle.

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Guillain-Barre syndrome occurs when the body's own immune system attacks and injures the nerves outside of the spinal cord or brain – the peripheral nervous system. Niq Steele / Getty Images

By Sherry H-Y. Chou, Aarti Sarwal and Neha S. Dangayach

The patient in the case report (let's call him Tom) was 54 and in good health. For two days in May, he felt unwell and was too weak to get out of bed. When his family finally brought him to the hospital, doctors found that he had a fever and signs of a severe infection, or sepsis. He tested positive for SARS-CoV-2, the virus that causes COVID-19 infection. In addition to symptoms of COVID-19, he was also too weak to move his legs.

When a neurologist examined him, Tom was diagnosed with Guillain-Barre Syndrome, an autoimmune disease that causes abnormal sensation and weakness due to delays in sending signals through the nerves. Usually reversible, in severe cases it can cause prolonged paralysis involving breathing muscles, require ventilator support and sometimes leave permanent neurological deficits. Early recognition by expert neurologists is key to proper treatment.

We are neurologists specializing in intensive care and leading studies related to neurological complications from COVID-19. Given the occurrence of Guillain-Barre Syndrome in prior pandemics with other corona viruses like SARS and MERS, we are investigating a possible link between Guillain-Barre Syndrome and COVID-19 and tracking published reports to see if there is any link between Guillain-Barre Syndrome and COVID-19.

Some patients may not seek timely medical care for neurological symptoms like prolonged headache, vision loss and new muscle weakness due to fear of getting exposed to virus in the emergency setting. People need to know that medical facilities have taken full precautions to protect patients. Seeking timely medical evaluation for neurological symptoms can help treat many of these diseases.

What Is Guillain-Barre Syndrome?

Guillain-Barre syndrome occurs when the body's own immune system attacks and injures the nerves outside of the spinal cord or brain – the peripheral nervous system. Most commonly, the injury involves the protective sheath, or myelin, that wraps nerves and is essential to nerve function.

Without the myelin sheath, signals that go through a nerve are slowed or lost, which causes the nerve to malfunction.

To diagnose Guillain-Barre Syndrome, neurologists perform a detailed neurological exam. Due to the nerve injury, patients often may have loss of reflexes on examination. Doctors often need to perform a lumbar puncture, otherwise known as spinal tap, to sample spinal fluid and look for signs of inflammation and abnormal antibodies.

Studies have shown that giving patients an infusion of antibodies derived from donated blood or plasma exchange – a process that cleans patients' blood of harmful antibodies - can speed up recovery. A very small subset of patients may need these therapies long-term.

The majority of Guillain-Barre Syndrome patients improve within a few weeks and eventually can make a full recovery. However, some patients with Guillain-Barre Syndrome have lingering symptoms including weakness and abnormal sensations in arms and/or legs; rarely patients may be bedridden or disabled long-term.

Guillain-Barre Syndrome and Pandemics

As the COVID-19 pandemic sweeps across the globe, many neurologic specialists have been on the lookout for potentially serious nervous system complications such as Guillain-Barre Syndrome.

Though Guillain-Barre Syndrome is rare, it is well known to emerge following bacterial infections, such as Campylobacter jejuni, a common cause of food poisoning, and a multitude of viral infections including the flu virus, Zika virus and other coronaviruses.

Studies showed an increase in Guillain-Barre Syndrome cases following the 2009 H1N1 flu pandemic, suggesting a possible connection. The presumed cause for this link is that the body's own immune response to fight the infection turns on itself and attacks the peripheral nerves. This is called an "autoimmune" condition. When a pandemic affects as many people as our current COVID-19 crisis, even a rare complication can become a significant public health problem. That is especially true for one that causes neurological dysfunction where the recovery takes a long time and may be incomplete.

The first reports of Guillain-Barre Syndrome in COVID-19 pandemic originated from Italy, Spain and China, where the pandemic surged before the U.S. crisis.

Though there is clear clinical suspicion that COVID-19 can lead to Guillain-Barre Syndrome, many important questions remain. What are the chances that someone gets Guillain-Barre Syndrome during or following a COVID-19 infection? Does Guillain-Barre Syndrome happen more often in those who have been infected with COVID-19 compared to other types of infections, such as the flu?

The only way to get answers is through a prospective study where doctors perform systematic surveillance and collect data on a large group of patients. There are ongoing large research consortia hard at work to figure out answers to these questions.

Understanding the Association Between COVID-19 and Guillain-Barre Syndrome

While large research studies are underway, overall it appears that Guillain-Barre Syndrome is a rare but serious phenomenon possibly linked to COVID-19. Given that more than 10.7 million cases have been reported for COVID-19, there have been 10 reported cases of COVID-19 patients with Guillain-Barre Syndrome so far – only two reported cases in the U.S., five in Italy, two cases in Iran and one from Wuhan, China.

It is certainly possible that there are other cases that have not been reported. The Global Consortium Study of Neurological Dysfunctions in COVID-19 is actively underway to find out how often neurological problems like Guillain-Barre Syndrome is seen in hospitalized COVID-19 patients. Also, just because Guillain-Barre Syndrome occurs in a patient diagnosed with COVID-19, that does not imply that it was caused by the virus; this still may be a coincident occurrence. More research is needed to understand how the two events are related.

Due to the pandemic and infection-containment considerations, diagnostic tests, such as a nerve conduction study that used to be routine for patients with suspected Guillain-Barre Syndrome, are more difficult to do. In both U.S. cases, the initial diagnosis and treatment were all based on clinical examination by a neurological experts rather than any tests. Both patients survived but with significant residual weakness at the time these case reports came out, but that is not uncommon for Guillain-Barre Syndrome patients. The road to recovery may sometimes be long, but many patients can make a full recovery with time.

Though the reported cases of Guillain-Barre Syndrome so far all have severe symptoms, this is not uncommon in a pandemic situation where the less sick patients may stay home and not present for medical care for fear of being exposed to the virus. This, plus the limited COVID-19 testing capability across the U.S., may skew our current detection of Guillain-Barre Syndrome cases toward the sicker patients who have to go to a hospital. In general, the majority of Guillain-Barre Syndrome patients do recover, given enough time. We do not yet know whether this is true for COVID-19-related cases at this stage of the pandemic. We and colleagues around the world are working around the clock to find answers to these critical questions.

Sherry H-Y. Chou is an Associate Professor of Critical Care Medicine, Neurology, and Neurosurgery, University of Pittsburgh.

Aarti Sarwal is an Associate Professor, Neurology, Wake Forest University.

Neha S. Dangayach is an Assistant Professor of Neurology and Neurosurgery, Icahn School of Medicine at Mount Sinai.

Disclosure statement: Sherry H-Y. Chou receives funding from The University of Pittsburgh Clinical Translational Science Institute (CTSI), the National Institute of Health, and the University of Pittsburgh School of Medicine Dean's Faculty Advancement Award. Sherry H-Y. Chou is a member of Board of Directors for the Neurocritical Care Society. Neha S. Dangayach receives funding from the Bee Foundation, the Friedman Brain Institute, the Neurocritical Care Society, InCHIP-UConn Center for mHealth and Social Media Seed Grant. She is faculty for emcrit.org and for AiSinai. Aarti Sarwal does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Reposted with permission from The Conversation.