A fungal ‘superbug’ causes global amphibian declines

by Anonymous (not verified) on

  Find out how ZSL scientists discovered the link between the frog trade and a killer fungus seriously effecting amphibians worldwide with Frog Blog

My name is Rhys and I am a postgraduate student at Imperial College London and the Zoological Society of London (ZSL). For the past two years I have been studying a chytrid fungus known as Bd, which is responsible for likely hundreds of extinctions and local extinctions (extirpations) in amphibians worldwide. Our group is interested in understanding how -until recently- an unknown disease can emerge to become a major driver of population declines in vertebrates world-wide. To answer this question, we have travelled to habitats across the globe to both sample and record the prevalence of this fungus in wild populations, focussing in particular on amphibian populations in Europe. We have taken samples from amphibians across a diverse range of habitats from the mountains of the French Pyrenees to northern Mallorca, recovering isolates of Bd that appeared to be markedly different from one another in their microscopic characteristics.

Collecting Alytes obstetricans tadpoles from a Bd+ site in Switzerland

But why do they appear different? To explain, we compared the differences between their genomes (genetic history). This showed us that Bd consists of at least three separate and divergent lineages, each likely to have been spread, and potentially to have come into contact with one another via the global trade of amphibians. The global trade of live amphibians supplies amphibians for human consumption, the pet trade, lab animal trade and zoos and in many ways is largely unregulated. One of these Bd lineages also has features within the genome that may have resulted from hybridization between two parental strains of the disease. Our data shows that this is the most common type of Bd, and also the type associated with mass-death and extinction of whole species. Lab experiments show that this lineage is hyper-virulent when compared with the other identified lineages. These findings raise an interesting possibility: that extinctions from Bd are not solely caused by introduction into naive populations, but that the largely unregulated trade in amphibians has inadvertently created this fungal super-bug. Preventing future panzootics therefore may rest in readdressing the measures used to prevent transmission of infectious diseases (biosecurity) in the amphibian trade to prevent accelerated evolution and spread of hyper-virulent diseases in the future.   Rhys Farrer

Select a blog

Videographer Blog

One man is boldly going where no other ZSL videographer has gone before - the land of Mountain Chicken Frogs. Armed with nothing more than a camera and some factor 60 suncream, he will share with you his adventures in the Caribbean as he follows ZSL's work with this endangered amphibean. 

Discovery and Learning in the Field

Join the ZSL Discovery and Learning team as they venture out of the zoo and in to the wild.

Conservation

Catch up on our latest Conservation Blogs

Tiger conservation

Read about conservation of tigers in Asia.

Wild Science

From the field, to the lab, to the analysis, catch up with the scientists at ZSL’s Institute of Zoology, our world-renowned research centre working at the cutting edge of conservation biology.

Wildlife Wood Project Cameroon

The Wildlife Wood Project has been working in Cameroon since 2007 to encourage better wildlife management in logging concessions.

Penguin expedition blog

Updates from penguin conservation expeditions to Antarctica

Amur Leopard

Amur leopard conservation blog

Baby Giraffe Diaries

Meet ZSL Whipsnade Zoo's latest (and leggiest) arrival, a baby giraffe!

Biodiversity and Palm Oil

Follow the ZSL Biodiversity and Palm Oil team, based in Bogor, Indonesia.

Chagos Expedition

The Chagos marine reserve, designated in 2010 and currently the world’s largest no take marine reserve, is a sought-after spot for marine research.

Frog Blog

Follow ZSL’s amphibian experts in their quest to find out why 41% of the world’s amphibians are threatened and what can be done to stop more species becoming extinct.

Tsaobis Baboon Blog

Follow ZSL conservationists studying desert baboons in Namibia.