The fungus in the epidermis has a thallus bearing a network of rhizoids and smooth-walled, roughly spherical, inoperculate (without an operculum) sporangia.

[8] However, the zoospores are capable of chemotaxis, and can move towards a variety of molecules that are present on the amphibian surface, such as sugars, proteins and amino acids.

[10] Once the zoospore reaches its host, it forms a cyst underneath the surface of the skin, and initiates the reproductive portion of its life cycle.

[12] Besides amphibians B. dendrobatidis also infects crayfish (Procambarus alleni, P. clarkii, Orconectes virilis, and O. immunis) but not mosquitofish (Gambusia holbrooki).

For example, before the 2003 European heat wave that decimated populations of the water frog Rana lessonae through chytridiomycosis, the fungus existed on the amphibians as spherical, unicellular organisms, confined to minute patches (80-120 μm across).

Characteristics of the organisms were suggestive of encysted zoospores; they may have embodied a resting spore, a saprobe, or a parasitic form of the fungus that is non-pathogenic.

[18] It has been suggested that B. dendrobatidis originated in Africa or Asia and subsequently spread to other parts of the world by trade in African clawed frogs (Xenopus laevis).

[20] American bullfrogs (Lithobates catesbeianus), also widely distributed, are also thought to be carriers of the disease due to their inherent low susceptibility to B. dendrobatidis infection.

[36] While most studies concerning B. dendrobatidis have been performed in various locations across the world, the presence of the fungus in Southeast Asia remains a relatively recent development.

[40] Soon thereafter, mainland Asian countries such as Thailand,[41] South Korea,[42] and China[43] reported incidents of B. dendrobatidis among their amphibian populations.

Much effort has been put into classifying herpetofauna in countries like Cambodia, Vietnam, and Laos where new species of frogs, toads, and other amphibians and reptiles are being discovered on a frequent basis.

[citation needed] Scientists simultaneously are swabbing herpetofauna in order to determine if these newly discovered animals possess traces of the fungus.

[44] Another study in Cambodia questioned the potential anthropological impact in the dissemination of B. dendrobatidis on local amphibian populations in three different areas in relation to human interaction: low (an isolated forest atop a mountain people rarely visit), medium (a forest road ~15 km from a village that is used at least once a week), and high (a small village where humans interact with their environment on a daily basis).

[45] Human influence most likely explains detection of the fungus in the medium and high areas, however it does not provide an adequate explanation why even isolated amphibians were positive for B. dendrobatidis.

Worldwide amphibian populations have been on a steady decline due to an increase in the disease chytridiomycosis, caused by the Bd fungus.

Potential effects of this pathogen are hyperkeratosis, epidermal hyperplasia, ulcers, and most prominently the change in osmotic regulation often leading to cardiac arrest.

[49][50] For example, the Fletcher frog, despite practising skin sloughing, suffers from a particularly high mortality rate when infected with the disease compared to similar species like Lim.

[51] According to a study by the Australian National University, the Bd fungus has caused the decline of 501 amphibian species—about 6.5 percent of the world's known total.