# "Scientists discover method to eliminate killer fungus in amphibians" - ZSL



## rvsur (Dec 13, 2010)

I came across this article by the Zoological Society of London and thought you all might be interested in giving it a read. The method described sounds a bit intensive but it is a huge step in the right direction from what I can gather. I was hoping some of you might be able to expand on what this might mean.


Scientists discover method to eliminate killer fungus in amphibians - Zoological Society of London

Theres a brief summary video included in the article that gave a pretty good rundown.


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## Rushthezeppelin (Oct 6, 2015)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

Just saw this in a FB group and was coming to post. Possibly promising for sure. I'm just wondering what the sterilization chemical does or doesn't do to the rest of the micro-diversity in the soil. Have they developed something that only fights the chytrid? If they get it wrong it could end up killing phib populations anyway due to the destruction of their food chain.


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## adolph123 (Feb 24, 2016)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

Hopefully this works which out causing more problems. I once saw something similar on treatment of other amphibians

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## Ed (Sep 19, 2004)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

Unfortunately its only likely to be effective on very small locations that are isolated from other infected sites (which is why they did it on an island). 

Its been detected in rainfall, the feet of water fowl

Kolby, Jonathan E., et al. "Presence of amphibian chytrid fungus (Batrachochytrium dendrobatidis) in rainwater suggests aerial dispersal is possible." Aerobiologia 31.3 (2015): 411-419.

Garmyn, An, et al. "Waterfowl: potential environmental reservoirs of the chytrid fungus Batrachochytrium dendrobatidis." PLoS One 7.4 (2012): e35038.

There was a paper a number of years back that indicated that crayfish could harbor chytrid but it was subsequently retracted but now it looks like another group has nailed it. 

McMahon, Taegan A., et al. "Chytrid fungus Batrachochytrium dendrobatidis has nonamphibian hosts and releases chemicals that cause pathology in the absence of infection." Proceedings of the National Academy of Sciences 110.1 (2013): 210-215.

I have serious doubts given the above data that the island will remain chytrid free in the long-term. 

Some comments 

Ed


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## Woodswalker (Dec 26, 2014)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

I was wondering about the risk for reinfection, too. 

That some host species (crayfish, according to your article) can release chemicals that cause damage to amphibians in the absence of infection is also troubling. 

What's interesting about that, however, is that it may open another avenue for exploring a solution. I did not read the article, so I may be entirely off base, but the headline at least suggests that the toxins could be isolated, and _iff_ that is indeed what causes illness, that might be promising. By identifying the toxin produced by the fungus, perhaps the currently harmful strain(s) of Bd could be manipulated favorably.

If strains of Bd could be bred that did not produce the toxins that cause harm, it may be worth studying the possibility of introducing modified, innocuous strains of Bd in the hopes that they outcompete the pathogenic strain(s). Even if that were successful, the law of unintended consequences could always intervene, of course. I hope there's already similar research underway. 

[Iff = if and ONLY if]


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## Ed (Sep 19, 2004)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

The problem is that the infection of the keratin in the skin also disrupts the electrolyte/osmotic functions of the skin. see Campbell, Craig R., et al. "Frog skin epithelium: electrolyte transport and chytridiomycosis." The international journal of biochemistry & cell biology 44.3 (2012): 431-434.

some comments 

Ed


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## Woodswalker (Dec 26, 2014)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

Do you know where I might be able to read that online? I'd be interested to see what that says about the mechanism of disease. If you don't know offhand, I will see if one of my local libraries has that. UM is nearby, so I may find it there.


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## Woodswalker (Dec 26, 2014)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

Ooh, hey! I found it! I hope this is the same one.

Frog skin epithelium: electrolyte transport and chytridiomycosis


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## Woodswalker (Dec 26, 2014)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

That's interesting. So, from the article, "So far, the mechanism underlying the development of hypokalemia in Bd-infected frogs remains elusive." 

The cause of death seems to be that the frogs' levels of potassium (K+, the cation) fall below acceptable levels. Yet, they don't know what is causing that to occur. I think that still leaves open the possibility that the toxin secreted by the fungus could be what's affecting the sodium and potassium channels.


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## Woodswalker (Dec 26, 2014)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

The crayfish study cited above sounds really exciting. After reading it, it does appear that they're getting closer to identifying the mechanism for disease. It looks like this is the current avenue of study. "Whether these pathology-inducing chemicals released by B. dendrobatidis are known proteases (22, 29⇓–31) and are the cause of B. dendrobatidis–induced electrolyte imbalance and cardiac arrest in amphibians (37) remains to be tested."


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## Ed (Sep 19, 2004)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

The problem with attempting to replace the virulent populations with non-virulent strain(s) is that the lab strains are going to be adapted to maximal growth in the labs. If you attempt to culture and test them where the pathogen can escape to the wild, you could actually make the entire system worse as there can be an exchange of genes which can make the entire problem worse (which is the scenario they suspect drives the current crisis). 

There is good evidence that the hypervirulent stains are due to recombination/hybridization and that there are less virulent or avirulent strains (or possibly cryptic species). 
see http://plantpath.wsu.edu/wp-content/uploads/2014/01/PNAS-2011-Farrer-Multiple-emergences-.pdf

Farrera, Rhys A., et al. "Multiple emergences of genetically diverse amphibian-infecting chytrids include a globalized hypervirulent recombinant lineage."

some comments 

Ed


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## Trojan (Oct 15, 2014)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

After reading this, I am very weary of resistance. Dont get me wrong, this is very exciting, I am just curious how to treat populations on a large scale without creating a more resistant pathogen. I feel like even without the development of a resistant strain the process of clearing wild populations would be ongoing. I am more curious to see if there is a way to treat the pathogen through competition of another microbe. Does anyone know if that has been looked into?


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## Ed (Sep 19, 2004)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*



Trojan said:


> After reading this, I am very weary of resistance. Dont get me wrong, this is very exciting, I am just curious how to treat populations on a large scale without creating a more resistant pathogen. I feel like even without the development of a resistant strain the process of clearing wild populations would be ongoing. I am more curious to see if there is a way to treat the pathogen through competition of another microbe. Does anyone know if that has been looked into?


I'm not as concerned about resistance as I am about the contact of multiple strains/species which can continue the evolution of a hypervirulent strain. 
This is why that all waste water should be bleached and all solid materials double bagged and placed into the correct waste stream and not composted. 

To answer your question yes there have been studies for competing microbes and yes they have found bacterial populations that inhibit/prevent the fungus from infecting/killing the frogs. see
The ISME Journal - Abstract of article: Skin microbes on frogs prevent morbidity and mortality caused by a lethal skin fungus

Harris, Reid N., et al. "Skin microbes on frogs prevent morbidity and mortality caused by a lethal skin fungus." The ISME journal 3.7 (2009): 818-824. 

The problem is that the bacteria in this case are not found as a common presence in a wide number of bacterial populations. So while this can be effective in the lab there are practical issues with the implementation of it. For example, frogs treated with it can survive but that doesn't enable vertical transmission of the bacteria so that subsequent generations are able to benefit. It doesn't mean that it will persist in the wild but most importantly you have to directly dose the frogs. 

some comments 

Ed


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## Trojan (Oct 15, 2014)

*Re: "Scientists discover method to eliminate killer fungus in amphibians" - ZSL*

Thanks Ed that was great. I used to work with a herpetologist and icthyologist from Utah and we would study wild frog populations with chytrid and we looked into large poplulations. Eventually (with large populations) by exposing a pathogen to selection pressure, either a more virulent strain (as you said) or a resistant strain is bound to appear. When treating lake fish species for example this is not as big of an issue because there is less transfer between species so even if a strain arose it would likely be more isolated. But with frogs or amphibians as a whole I am concerned with transfer of the new strain after it occurs. Either way it is exciting that people are making progress and spending time on this.

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