Amphibian Parasites and Conservation
In general frogs harbour a lot of different parasites from protozoans, roundworms, flukes to tapeworms. In most cases frogs play an important role as intermediate or definitive host for many parasites. The clawed frog (Xenopus laevis) alone is host for no less than 25 different genera of parasites including all major parasitic groups except acanthocephalans. Monogeneans are mainly parasitic in fish but the family Polystomatidae radiated onto the tetrapods and are known from the skin and gills of the Australian lungfish, kidneys and urinary bladders of frogs, gills and skin of salamanders, cloaca and phallodeum of caecilians, on the eye, in the nose, mouth or urinary bladder of freshwater turtles and on the eye of the hippopotamus. These parasites vary from 2mm to more than 30mm in length. The body is elongated or somewhat pyriform, tapering anteriorly, with a haptor posteriorly.
Chytrid and Amphibian declines
Amphibians worldwide are currently experiencing a biodiversity crisis. For the past three decades, amphibian populations have been declining because of anthropogenic influences (most notably habitat loss), but also because of unknown causes in protected areas. One third of species are currently under threat and the rate of species extinction is the highest in recorded history. A large proportion of population declines during the past two decades has been attributed to the disease chytridiomycosis, caused by the amphibian chytrid fungus, Batrachochytrium dendrobatidis. Pathogenic infections of frogs by B. dendrobatidis often lead to amphibian population declines and occasional extirpations. Furthermore, recent evidence suggests that chytridiomycosis is spreading rapidly, sometimes resulting in the disappearance of rare and endemic amphibians.