The pandemic that threatens amphibians

Daniel Fernandez Guiberteau

Updated:12/07/2020 01:57h


The words emerging diseases, pandemic, biosecurity and asymptomatic carriers have become common among us in 2020, due to the misfortune of being a species affected by a highly contagious virus. But what would you tell me if I talked about ranavirus and chytridiomycosis? These two so-called emergent diseases, caused by a virus (the type 3 frog virus) and two species of highly pathogenic chytrid fungi (Batrachochytrium dendrobatidis, Bd; and Batrachochytrium salamandrivorans, Bsal), have caused the population decline of more than 500 species and more than 90 species have been taken from us in the silence of natural spaces around the world, in the last 50 years. Recent studies indicate that the origin of these diseases is Asia, assuming that the expansion of these pathogens occurs from that continent due to the animal trade. The discovery of Bd was published in 1999 and, since then, various research teams around the world have treated these diseases in the laboratory in a totally viable way. However, the habitat where these pathogens appear is forever affected; although on rare occasions and depending on the characteristics of the affected area, its eradication has been possible. When one of these chytrids comes into contact with a specimen of a vulnerable species, it settles on your skin, feeding on your keratin and growing to complete its biological cycle like all living beings. At the end of their mission, the new generations (in the form of zoospores) pass through the host’s skin, causing irreversible damage and death. After this, the zoospores (millions) wait in the water for the passage of another unfortunate animal to serve as food.

In the Iberian Peninsula, Bd was described for the first time in 2001, after causing massive mortalities since 1997 in the Sierra de Guadarrama National Park; but at present it is highly distributed throughout the peninsula, with an unstoppable advance, closely followed by ranavirus. Bsal, from the same family as the one mentioned above, was described in 2013 after wiping out almost all of the salamander populations in the Netherlands, Belgium and a strip of Germany; but recently the first case was discovered in Spain, located in the Montnegre and Corredor Park, where it has caused mortalities of urodelos (newts and salamanders).

But what can we do to stop its advance? For now, and until we have a treatment that prevents eliminating these pathogens from the natural environment, what we must do is keep our distance with these animals and not come into contact with them; disinfect all material that comes into contact with the aquatic environment, wellies, waders, fishing gear, boats …; and using biosafety measures such as nitrile gloves and hydroalcoholic gel, something that 50 years ago was unthinkable that we would do and that unfortunately is now part of our daily lives.

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