# acquired immunity towards chytrid



## Rain_Frog (Apr 27, 2004)

This is an interesting article, and illustrates the increasing body of evidence that immunosuppression from pollutants or environmental / climatic stressors triggers chytrid outbreaks:

Amphibians May Develop Immunity To Fatal Fungus


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## MonarchzMan (Oct 23, 2006)

I saw something like this mentioned in the Nature documentary, and found it rather intriguing. There was a massive captive breeding program of Spotted Treefrogs in Australia and subsequent release of many of them into a chytrid-infected area. Losses were great, but few animals did manage to survive and have immunity towards the disease. I wonder if this could be done with species like Atelopus zeteki here in the U.S. and do a massive release. Most would likely die, but there's the chance that some could develop immunity, and then use those animals to re-establish the populations. It would seem a good use of the animals since at this point zoos can't breed them due to their amazing success in captivity. There would be causalties, sure, but they're euthanizing excess animals anyway, might as well see if they could be used to re-establish populations.


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## Rain_Frog (Apr 27, 2004)

Yah, I saw that too in the Thin Green Line, about the treefrogs.

However, the article discusses how frogs can be "toughened up" by exposure to chytrid when it's weakened, or once they are cured of it the first time.

I think we'll eventually figure out what pollutant / environmental change is immunosuppressing frogs and find probiotics or other techniques to make them resistant.

I suspect that chytrid is more present in our collections than we think, but our frogs may have developed some form of immunity towards it, making them potential vectors.


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## Otis (Apr 16, 2006)

MonarchzMan said:


> I saw something like this mentioned in the Nature documentary, and found it rather intriguing. There was a massive captive breeding program of Spotted Treefrogs in Australia and subsequent release of many of them into a chytrid-infected area. Losses were great, but few animals did manage to survive and have immunity towards the disease. I wonder if this could be done with species like Atelopus zeteki here in the U.S. and do a massive release. Most would likely die, but there's the chance that some could develop immunity, and then use those animals to re-establish the populations. It would seem a good use of the animals since at this point zoos can't breed them due to their amazing success in captivity. There would be causalties, sure, but they're euthanizing excess animals anyway, might as well see if they could be used to re-establish populations.


I remember reading somewhere that the Australian (Taudactylus eubgellensis) showed a low immunity to the fungus in past years, but more recently healthy populations was found in an area where the fungi was still present. 

Nothing huge, but it's certainly better than nothing.


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## MonarchzMan (Oct 23, 2006)

Rain_Frog said:


> I suspect that chytrid is more present in our collections than we think, but our frogs may have developed some form of immunity towards it, making them potential vectors.


I totally agree. I know that MI has chytrid, and I would be incredibly surprised if it didn't find its way into my collection. I would guess that the nutrients, pampered lifestyle, and being well fed all contribute to them not displaying symptoms of the disease. I'd guess that any continual stress over time leads them to display symptoms.


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## Rain_Frog (Apr 27, 2004)

Sometimes pumilio are infected with chytrid when they are imported. I have strong suspicions that many pumilio are asymptopic because they prefer warmer and drier temperatures than most darts.


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## MonarchzMan (Oct 23, 2006)

Rain_Frog said:


> Sometimes pumilio are infected with chytrid when they are imported. I have strong suspicions that many pumilio are asymptopic because they prefer warmer and drier temperatures than most darts.


There was a paper done by Richards et al last year that did a chytrid assay on Bastimentos frogs. She sampled 84 frogs (I believe) across the island and didn't find chytrid at all in the population, which I found surprising. I hope to do a chytrid assay through many populations to see if it's true throughout the archipelago. I'm guessing that chytrid is there, but pumilio (and likely other darts) are not affected by it (or affected very minimally) because they breed in small amounts of water and because they do not have the traditional amplexus which has been shown to pass chytrid fairly efficiently due to the contact of the moist venter. I'm gonna try to do an assay on Cane Toads too which, if chytrid is there, should have it because they're pond breeders.


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## Rain_Frog (Apr 27, 2004)

also keep in mind that chytrid stops growing at above 76 degrees F-- and many pumilio can be found in habitats where temps regularly exceed 80 degrees.


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## MonarchzMan (Oct 23, 2006)

Rain_Frog said:


> also keep in mind that chytrid stops growing at above 76 degrees F-- and many pumilio can be found in habitats where temps regularly exceed 80 degrees.


Right, but if they contracted it, they would show infection, I'd assume, just not the symptoms of it because it was being suppressed by the temperatures.


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## Ed (Sep 19, 2004)

Pumilio has been documented as having chytrid in the wild. Asymptomatic infections occur at temperatures above 76 F and by definition do not show symptoms. 

I believe this paper has references to pumilio being infected (I don't have it in front of me so I can't be sure off hand) ScienceDirect - Biological Conservation : The amphibian chytrid fungus along an altitudinal transect before the first reported declines in Costa Rica
As noted in the paper chytrid is infecting amphibians at lower warmer altitudes, it just isn't killing them as it remains asymptomatic. 

and you can check out the statement here IUCN 2008 Red List - Oophaga pumilio on it being found in museum specimens of pumilio. 


Ed


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## ZeFrog (Apr 9, 2009)

Thanks for the link. I saw a documentary on this a few weeks ago, it was pretty devastating. I found it amazing that one man, one frog at a time decided upon himself that it was time to make a difference and do his part in saving the frogs.


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