Disease Forms - Amphibian Chytrid Fungus Disease

Question 1

What is Amphibian Chytrid Fungus Disease?

Answer 1

(Batrachochytrium dendrobatidis) - infects and kills amphibians.

Question 2

How does the disease work?

Answer 2

Infects the skin - outer keratin layers are damaged, disrupting respiration, salt regulation and osmoregulation. Can also produce a toxin that enters the bloodstream - attacking the nervous system and disrupting regular behaviour.

Question 3

What are the symptoms of this disease?

Answer 3

• Discoloured skin
• Skin layers peeling
• Sitting in exposed areas
• Sluggish, reduced activity - no appetite
• Legs spread lighty away from body
• Sometimes; body is rigid, back legs will trail behind

Question 4

Outline its lifecycle.

Answer 4

• Lives in water/soil - reproduces asexually.
• Zoospore - singular prosterior flaggelum (motile in water).
• Zoospores released from infected frogs - attach and penetrate skin of new host.
• Zoospore absorb nutrients in the skin & develop into a thallus (sporangium).
• In the thallus, new zoospores produced; once matured (4-6 days) it bursts, releasing the zoospores into the water and host.

Question 5

Outline recent trends of the disease; particularly toward its distribution and environmental effect.

Answer 5

• Discovered in Aus in 1993, existing since the 70’s
• 90 species gone extinct
• Further 124 species in decline

Question 6

How is the disease transmitted to other amphibians?

Answer 6

The disease is transferred by direct contact between frogs & tadpoles or indirect contact from infected water.
Doesn’t kill the amphibian immediately - spreading more fungal spores (higher infectious rate).

Question 7

How may this be caused?

Answer 7

• More suitable environmental conditions for growth and survival.
• Reduced resistance to infection.
• Environmental change - climate change (?).