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Global Frog Pandemic May Become Even Deadlier as Strains Combine

Animals
The pumpkin toadlet (Brachycephalus ephippium), endemic to Brazil's Atlantic Forest, is highly susceptible to the hybrid Bd fungus. Gui Becker

By Morgan Erickson-Davis

A fungus that has decimated frog populations around the world could get even deadlier, according to new research. The study found that hybridization of different types of the fungus creates strains that can cause greater mortality in frogs. And it warns that deforestation could make this impact worse.


The fungus is called Batrachochytrium dendrobatidis—Bd for short—and it causes a disease called chytridiomycosis that affects a frog's ability to absorb water and electrolytes through its skin. Scientists first started to take notice in the 1970s when frog populations in Central and South America started disappearing.

By the 1990s Bd had spread around the world, likely aided by the laboratory trade in African clawed frogs and invasions of American bullfrogs. By 2007 it had been implicated in the decline or extinction of some 200 species.

Today, biologists consider it one of the biggest threats to amphibians globally.

Some research has offered a bit of hope for frogs, with a study published earlier this year in Science finding populations may be able to develop resistance to Bd.

But a new study published last week in Scientific Reports adds another hurdle for frogs, finding that hybridization between a native strain of Bd in Brazil and the one that's caused the global pandemic can lead to greater infection rates and illness strength than either can alone.

The study was conducted by researchers from universities in Brazil and the U.S. who looked at infection in several frog species native to Brazil's Atlantic Forest. They chose that region because of its high amphibian biodiversity (despite being one of the most deforested ecosystems on the planet) and because it's the only known region in the world where multiple strains of Bd coexist and hybridize.

Deforestation for agriculture and other development has reduced Brazil's Atlantic Forest to less than 15 percent of its original extent.Mongabay

Scientists believe the Brazilian strain of Bd (Bd-Brazil) evolved along with amphibian populations there and, because of this, is not as harmful to them as the Global Pandemic Lineage (Bd-GPL). But when the team compared infection and illness rates of the two types of Bd and a third hybridized one, they found that the latter had a significantly worse impact on two of the three frog species they examined.

The researchers write that this effect may be due to a phenomenon called "hybrid vigor" (also referred to as "heterosis"), by which the sudden surge in genetic diversity caused by hybridization leads to a more dramatic expression of advantageous physical traits. Take, for example, mules, which tend to be stronger (and smarter, according to at least one study) than either their horse or donkey parents. The same might be happening for Bd. Combining the genes of different strains of Bd could make a hybrid strain even stronger than Bd-GPL.

Another reason why hybrid Bd may be affecting frogs so profoundly is reduced genetic diversity in the frogs themselves. The authors write the pumpkin toadlet (Brachycephalus ephippium), one of the frog species that experienced high death rates when infected with the strain, lives in isolated, patchy habitats that "may have limited its exposure to pathogens throughout its evolutionary history or lowered its immunogenetic diversity."

The study's results appear to be already playing out in the real world, with previous research from the team finding that frog populations are declining and disappearing more quickly in the zone where the two Bd strains are known to hybridize.

And they warn that deforestation "may tip the host-pathogen balance further in favor of the pathogen" as habitat loss stands to increasingly isolate frog populations, further reducing their genetic diversity, while "even the most fragmented landscapes in the Atlantic Forest" don't seem to be a barrier to Bd.

The researchers say their results indicate frogs may face a future even more dire than anticipated as different strains of Bd spread around the world and combine into more harmful forms. They call for increasing global monitoring efforts to detect these shifts before they lead to new outbreaks.

"With globalization facilitating pathogen spread across continents, hybridization of chytrids might lead to new epidemic waves reducing amphibian biodiversity in both tropical and temperate regions," said study coauthor Gui Becker, assistant professor of biological sciences at the University of Alabama.

Reposted with permission from our media associate Mongabay.

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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.

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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.


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"We've moved the needle a lot, especially on environmental justice and upping Biden's ambition," said Sunrise Movement co-founder and executive director Varshini Prakash, a member of the Biden-Sanders Climate Task Force. "But there's still more work to do to push Democrats to act at the scale of the climate crisis."

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In a series of tweets Wednesday night, Ocasio-Cortez—the lead sponsor of the House Green New Deal resolution—noted that the Climate Task Force "shaved 15 years off Biden's previous target for 100% clean energy."

"Of course, like in any collaborative effort, there are areas of negotiation and compromise," said the New York Democrat. "But I do believe that the Climate Task Force effort meaningfully and substantively improved Biden's positions."

 

The 110 pages of policy recommendations from the six eight-person Unity Task Forces on education, the economy, criminal justice, immigration, climate change, and healthcare are aimed at shaping negotiations over the 2020 Democratic platform at the party's convention next month.

Sanders said that while the "end result isn't what I or my supporters would've written alone, the task forces have created a good policy blueprint that will move this country in a much-needed progressive direction and substantially improve the lives of working families throughout our country."

"I look forward to working with Vice President Biden to help him win this campaign," the Vermont senator added, "and to move this country forward toward economic, racial, social, and environmental justice."

Biden, for his part, applauded the task forces "for helping build a bold, transformative platform for our party and for our country."

"I am deeply grateful to Bernie Sanders for working with us to unite our party and deliver real, lasting change for generations to come," said the former vice president.

On the life-or-death matter of reforming America's dysfunctional private health insurance system—a subject on which Sanders and Biden clashed repeatedly throughout the Democratic primary process—the Unity Task Force affirmed healthcare as "a right" but did not embrace Medicare for All, the signature policy plank of the Vermont senator's presidential bid.

Instead, the panel recommended building on the Affordable Care Act by establishing a public option, investing in community health centers, and lowering prescription drug costs by allowing the federal government to negotiate prices. The task force also endorsed making all Covid-19 testing, treatments, and potential vaccines free and expanding Medicaid for the duration of the pandemic.

"It has always been a crisis that tens of millions of Americans have no or inadequate health insurance—but in a pandemic, it's potentially catastrophic for public health," the task force wrote.

Dr. Abdul El-Sayed, a former Michigan gubernatorial candidate and Sanders-appointed member of the Healthcare Task Force, said that despite major disagreements, the panel "came to recommendations that will yield one of the most progressive Democratic campaign platforms in history—though we have further yet to go."

 

Observers and advocacy groups also applauded the Unity Task Forces for recommending the creation of a postal banking system, endorsing a ban on for-profit charter schools, ending the use of private prisons, and imposing a 100-day moratorium on deportations "while conducting a full-scale study on current practices to develop recommendations for transforming enforcement policies and practices at ICE and CBP."

Marisa Franco, director of immigrant rights group Mijente, said in a statement that "going into these task force negotiations, we knew we were going to have to push Biden past his comfort zone, both to reconcile with past offenses and to carve a new path forward."

"That is exactly what we did, unapologetically," said Franco, a member of the Immigration Task Force. "For years, Mijente, along with the broader immigrant rights movement, has fought to reshape the narrative around immigration towards racial justice and to focus these very demands. We expect Biden and the Democratic Party to implement them in their entirety."

"There is no going back," Franco added. "Not an inch, not a step. We must only move forward from here."

Reposted with permission from Common Dreams.