bD

Bd is an abbreviation that appears in different fields. In biology and conservation, Bd most commonly refers to Batrachochytrium dendrobatidis, a pathogenic chytrid fungus responsible for chytridiomycosis in amphibians. Bd belongs to the phylum Chytridiomycota and was described in 1999. The organism infects the keratinized epidermis of amphibians, disrupting skin function and osmoregulation, often leading to death. Its life cycle alternates between motile zoospores that swim in aquatic environments and thalli that colonize host skin. Bd has been detected in hundreds of amphibian species across multiple continents, and is implicated as a major driver of global amphibian declines and extinctions. Transmission occurs through direct contact and contaminated water or substrates. Diagnosis commonly uses quantitative PCR on skin swabs; histology and culture can be used in research settings. In captive populations, antifungal treatments (such as itraconazole) have been used, and management focuses on surveillance, biosecurity, and the maintenance of amphibian refugia to support resistant populations. Conservation programs emphasize monitoring, rapid response to outbreaks, and habitat management to reduce Bd transmission risk. Research continues on environmental reservoirs, host susceptibility, and potential vaccines or probiotics, though no universally effective field remedy exists.

Bd may also refer to the country Bangladesh in some contexts, using the ISO 3166-1 alpha-2 code BD and the internet domain suffix .bd; however, formal abbreviations typically use BD (uppercase) for the country, not Bd.