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Two New Ways To Prevent Cholera: Microbes Fighting Microbes

The research has so far only been done in animals

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A woman draws water from an unprotected well in Chigwirizano, a peri-urban area hit by a Cholera outbreak in Malawi.
A woman draws water from an unprotected well in Chigwirizano, a peri-urban area hit by a Cholera outbreak in Malawi. VOA
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Two promising new ways to prevent cholera are on the horizon. One is an entirely new kind of vaccine. The other is as simple as a cup of yogurt.

Both may offer fast, cheap protection from explosive outbreaks of a disease that claims tens of thousands of lives each year.

The research has so far only been done in animals. Human studies are yet to come.

Cholera declawed

Cholera causes such serious diarrhea that it can kill within hours. Current vaccines take at least 10 days to work, don’t provide complete protection and don’t work well for young children.

One group of scientists working to create a better vaccine engineered cholera bacteria that are missing the genes that make the microbe toxic.

The researchers fed the modified bacteria to rabbits. The microbes colonized the animals’ guts but did not make them sick.

When the scientists then fed rabbits normal, disease-causing cholera 24 hours later, most of the animals survived.

Those that did get sick took longer to do so than rabbits given unmodified bacteria, or modified bacteria that had been killed. Those animals died within hours.

Doctors Giving vaccines
Doctors Giving vaccines, Pixabay

The engineered cholera bacteria provided protection much faster than a conventional vaccine. They acted as a probiotic: colonized the animals’ intestines in less than a day and prevented the disease-causing microbes from getting a foothold.

The researchers expect that the modified bacteria will also act like a typical vaccine, stimulating the body’s immune system to fight a future cholera infection.

“This is a new type of therapy,” Harvard University Medical School microbiologist Matthew Waldor said. “It’s both a probiotic and a vaccine. We don’t know the right name for it yet.”

The research is published in the Science Translational Medicine journal.

Yogurt solution

In another study in the same journal, a group of researchers discovered that a microbe commonly found in yogurt, cheese and other fermented dairy products can prevent cholera infection.

Bioengineer Jim Collins at the Massachusetts Institute of Technology and colleagues had been working on genetically modifying the bacteria, known as Lactococcus lactis, to treat cholera.

It hadn’t been working.

But they accidentally discovered that unmodified L. lactis keeps cholera germs in check by producing acid that the disease-causing microbes can’t tolerate.

Feeding mice doses of L. lactis bacteria every 10 hours nearly doubled their survival rate from cholera infection.

“It was remarkably surprising and satisfying,” Colllins said. “We were really getting frustrated.”

They also designed a strain of L. lactis that turns a cholera-infected mouse’s stool red. It could be a useful diagnostic, for example, to identify those carrying the bacteria but not showing symptoms.

Collins said pills of L. lactis bacteria — or simply ample supplies of fermented milk products — could be “a very inexpensive, safe and easy-to-administer way to keep some of these outbreaks in check.”

Waldor said his group’s modified-cholera vaccine also could be grown and packaged in pills quickly and easily in case of an outbreak.

Both caution that these animal studies are a long way from new treatments for human patients. They need to be proven in clinical trials.

Microscopic Image Of a Virus
Microscopic Image Of a Virus, Pixabay

Beyond cholera

The two studies could not only have an impact on cholera, but could also influence how doctors treat other intestinal diseases and manage gut health, according to Robert Hall, who oversees research funded by the National Institute of Allergy and Infectious Diseases.

While fermented foods promising better health are widely available, “the studies with probiotics in the field have really seldom shown great effectiveness when they’re done scientifically,” Hall said.

The work Collins’s group did not only shows effectiveness, but explains how it works: by “making the intestine inhospitable” to cholera, he added.

Hall wrote a commentary accompanying the two studies.

Other gut diseases work the same way as cholera, he noted, so it’s possible that other microbes could be developed that block harmful germs from gaining a foothold while acting as vaccines at the same time.

Also read: Lack of Toilets, Clean Drinking Water Pose Cholera Threat in Rohingya Refugee Camps

“It’s a very exciting principle,” Hall said. (VOA)

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Invasive Species May Not Be All Bad: Scientists

An active debate among biologists about the role of invasive species in a changing world is going on

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Invasive Species
The invasive European green crab is tearing down ecosystems in Newfoundland and building them up on Cape Cod. VOA

Off the shores of Newfoundland, Canada, an ecosystem is unraveling at the hands (or pincers) of an invasive crab.

Some 1,500 kilometers (930 miles) to the south, the same invasive crab — the European green crab — is helping New England marshes rebuild.

Both cases are featured in a new study that shows how the impacts of these alien invaders are not always straightforward.

Around the world, invasive species are a major threat to many coastal ecosystems and the benefits they provide, from food to clean water. Attitudes among scientists are evolving, however, as more research demonstrates that they occasionally carry a hidden upside.

“It’s complicated,” said Christina Simkanin, a biologist at the Smithsonian Environmental Research Center, “which isn’t a super-satisfying answer if you want a direct, should we keep it or should we not? But it’s the reality.”

Simkanin co-authored a new study showing that on the whole, coastal ecosystems store more carbon when they are overrun by invasive species.

Good news, crab news

Take the contradictory case of the European green crab. These invaders were first spotted in Newfoundland in 2007. Since then, they have devastated eelgrass habitats, digging up native vegetation as they burrow for shelter or dig for prey. Eelgrass is down 50 percent in places the crabs have moved into. Some sites have suffered total collapse.

That’s been devastating for fish that spend their juvenile days among the seagrass. Where the invasive crabs have moved in, the total weight of fish is down tenfold.

The loss of eelgrass also means these underwater meadows soak up less planet-warming carbon dioxide from the atmosphere.

In Cape Cod, Massachusetts, the same crab is having the opposite impact.

Off the coast of New England, fishermen have caught too many striped bass and blue crabs. These species used to keep native crab populations in check. Without predators to hold them back, native crabs are devouring the marshes.

But the invasive European green crab pushes native crabs out of their burrows. Under pressure from the invader, native crabs are eating less marsh grass. Marshes are recovering, and their carbon storage capacity is growing with them.

Invasive species
In this May 8, 2016 photo, eelgrass grows in sediment at Lowell’s Cove in Harpswell, Maine. VOA

Carbon repositories

Simkanin and colleagues compiled these studies and more than 100 others to see whether the net impact on carbon storage has been positive or negative.

They found that the ones overtaken by invasive species held about 40 percent more carbon than intact habitats.

They were taken by surprise, she said, because “non-native species are thought of as being negative so often. And they do have detrimental impacts. But in this case, they seem to be storing carbon quicker.”

At the Smithsonian Environmental Research Center where she works, the invasive reed Phragmites has been steadily overtaking a marsh scientists are studying.

Phragmites grows much taller, denser and with deeper roots than the native marsh grass it overruns.

But those same traits that make it a powerful invader also mean it stores more carbon than native species.

“Phragmites has been referred to as a Jekyll and Hyde species,” she said.

Not all invaded ecosystems stored more carbon. Invaded seagrass habitats generally lost carbon, and mangroves were basically unchanged. But on balance, gains from marsh invaders outweighed the others.

Invasive species
Phragmites plants growing on Staten Island draft in a breeze in the Oakwood Beach neighborhood of Staten Island. VOA

Not a lot of generalities

To be clear, Simkanin said the study is not suggesting it’s always better to let the invaders take over; but, it reflects an active debate among biologists about the role of invasive species in a changing world.

“One of the difficult things in the field of invasion biology is, there aren’t a lot of generalities,” said Brown University conservation biologist Dov Sax, who was not involved with the research. “There’s a lot of nuance.”

The prevailing view among biologists is that non-native species should be presumed to be destructive unless proven otherwise.

When 19 biologists wrote an article in 2011 challenging that view, titled, “Don’t judge species on their origins,” it drew a forceful rebuke from 141 other experts.

Sax said the argument is likely to become more complicated in the future.

Also Read: Climate Change Not A Hoax: Trump

“In a changing world, with a rapidly changing climate, we do expect there to be lots of cases where natives will no longer be as successful in a region. And some of the non-natives might actually step in and play some of those ecosystem services roles that we might want,” he said.

“In that context, what do we do? I definitely don’t have all the answers.” (VOA)