Joseph M. Groff; Albert Mughannam; Terry McDowell; Fredric L. Frye; Ronald P.
Hedrick
Morbidity and mortality approaching 100% occurred in Dwarf African Clawed
frogs Hymenochirus curtipes from a recirculating water culture facility in central
California. Moribund frogs exhibited preference for a terrestrial environment rather than their
normal aquatic environment. Affected animals had a slight pallor of the integument but were
otherwise grossly nonremarkable. Microscopic examination revealed a fungal infection of the
integument primarily characterized by the presence of surface and intraepidermal spores. Skip
cultures of the affected animals yielded an organism identified as Basidiobolus
meristosperus based on the production of sporangiospores. Electron microscope examination
of skin sections from infected animals wan consistent but not conclusive of B.
meristosporus. The organism was transmitted to healthy frogs via cohabitation with infected
frogs but not by short term immersion exposure of healthy frogs to homogenized culture isolates
of the fungus. Benzalkonium chloride at 4 ppm was efficacious in controlling the infection.
Although Basidiobolus is normally found in the intestinal tract of amphibians, the
severity of this epizootic indicates that B. meristosporus may be an important pathogen
of amphibians in culture facilities.