Batrachochytrium spp. are fungi which are being held responsible for large losses in amphibians.
The chytrid fungus Batrachochytrium (B.) dendrobatidis was first identified in Australia in 1998 and named in 1999. This fungus causes chytridiomycosis in anurans and salamanders and is thought to be partly responsible for the population decline and the global extinction of >200 amphibian species.
Infections with B. dendrobatidis are often associated with very high mortality rates (in lab up to 100%), but the fungus is not necessarily lethal. Other factors such as stress or co-infections with other pathogens also seem to play a role.
B. dendrobatidis multiplies in keratinised tissue and therefore affects primarily the outer skin of adult animals (stratum corneum to stratum granulosum).
In larvae the keratinised mouthparts are affected. During metamorphosis the infections can lead to dramatically high mortality rates. The clinical signs are often non-specific and may affect the skin (often appear macroscopically unchanged or “dull” or depigmented; hyperkeratosis and excessive episodes of skin shedding, mixed infections with severe erosions of the skin) as well as the behaviour (atypical behavior, such as prolonged stay in the water, ataxia and CNS problems). Spontaneous deaths without previous clinical manifestation are also observed.
Batrachochytrium salamandrivorans is a recently described highly-contagious and deadly chytrid fungus that has massively infested and killed fire salamanders especially in North-West Europe.
Infected animals show anorexia, apathy and ataxia as well as skin lesions with superficial erosions and deep ulcerations all over the body. Batrachochytrium salamandrivorans can also infect other salamanders, but has not yet been detected in anurans.