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From chytrid to ranavirus: Another disease is devastating frog populations

The views expressed are those of the author and are not necessarily those of Scientific American.


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The chytrid fungus (Batrachochytrium dendrobatidis) isn’t the only thing killing frogs and amphibians around the world. Now we have word that a disease from the genus Ranavirus is devastating frog populations in the U.K. According to research published in the October 2010 issue of Animal Conservation, the rapidly spreading ranavirus is killing common frogs (Rana temporaria) in areas where it has never been seen before. And where ranavirus is present in the U.K., common frog populations have dropped 81 percent in the last 12 years. The disease causes infected frogs to bleed to death through hemorrhaging organs and skin ulcerations.

Previously restricted to southeast England, and possibly introduced to the U.K. through imported frogs or fish, ranavirus has now spread to Lancashire in the west, Yorkshire in the north, and the south coast of the country. “[What] we desperately need to solve is how the disease spreads,” co-author Trent Garner of the Zoological Society of London (ZSL) said in a prepared statement.

“Our findings show that ranavirus not only causes one-off mass-mortality events, but is also responsible for long-term population declines,” lead author Amber Teacher, also from ZSL, said. “We need to understand more about this virus if we are to minimize the serious threat that it poses to our native amphibians.”

According to the paper’s abstract, this is the first study to examine the long-term impacts of ranavirus, although other studies (such as this one from the Archives of Virology or this one in the Journal of Wildlife Diseases) have looked at mass mortality events associated with the disease. Ranavirus has also been linked to mass deaths of salamanders, turtles and other amphibians worldwide.

There is good news amidst the bad: Some U.K. common frog populations managed to bounce back from ranavirus infections. This, the authors say, suggests that there may be some ranavirus immunity already present in some frogs.

Photo: Common frog (Rana temporaria), via Wikipedia





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  1. 1. Eric Mills 12:44 pm 10/14/2010

    Troubling news, indeed. A 2009 study in BIOLOGICAL CONSERVATION is recommended: "Magnitude of the US trade in amphibians and presence of Batrachochytrium dendrobatidis and ranavirus infection in imported North American bullfrogs (Rana catesbeiana)," by Lisa M. Schloegel,, Angela M. Picco, et al.

    According to this study, between 2000 and 2005, three U.S. ports (New York City, Los Angeles, San Francisco) imported a total of 28 MILLION live American bullfrogs, mostly for human consumption, most commercially-raised in Taiwan. Of those necropsied, 62% tested positive for the chytrid fungus, and 8.5% for ranavirus.

    Possible sources of the spread would seem to include live animal food markets (often in local "Chinatowns"), the pet trade and fishermen’s bait practices. And some religious sects routinely purchase market animals for "animal liberation" ceremonies.

    x
    Eric Mills, coordinator
    ACTION FOR ANIMALS
    Oakland, California

    Link to this
  2. 2. juanmartinez 5:46 am 02/18/2011

    Today, OIe has send an alert about Ranavirus infection in Netherlands afecting to Rana ridibunda: Information received on 18/02/2011 from Dr Christianne Bruschke, Chief Veterinary Officer , Ministry of Agriculture, Nature and Food Quality, Ministry of Agriculture, Nature and Food Quality, The Hague, Netherlands

    I have published an hypotheses that links amphibian extinction and public health: An aditional pollutant not previously considered that can acts as endocrine disrupting, are estrogens and progestagens, human and /or animal origen.

    J. Martínez Hernández, López-Rodas V, Segura R.
    Are human progestagens among the causes of
    amphibian extinction? Bioscience Hypotheses (2009) 2, 186-187

    Link to this

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