Batrachochytrium dendrobatidis is a fungus belonging to the Phylum Chytridiomycota, Class Chytridiomycetes, Order Chytridiales, and is the highly infectious aetiological agent responsible for a potentially fatal disease, chytridiomycosis, which is currently decimating many of the world's amphibian populations. The fungus infects 2 amphibian orders (Anura and Caudata), 14 families and at least 200 species and is responsible for at least 1 species extinction. Whilst the origin of the agent and routes of transmission are being debated, it has been recognised that successful management of the disease will require effective sampling regimes and detection assays. We have developed a range of unique sampling protocols together with diagnostic assays for the detection of B. dendrobatidis in both living and deceased tadpoles and adults. Here, we formally present our data and discuss them in respect to assay sensitivity, specificity, repeatability and reproducibility. We suggest that compliance with the recommended protocols will avoid the generation of spurious results, thereby providing the international scientific and regulatory community with a set of validated procedures which will assist in the successful management of chytridiomycosis in the future.

Mounting evidence implicates the disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis, in global amphibian declines and extinctions. While the virulence of this disease has been clearly demonstrated, there is, as yet, no mechanistic explanation for how B. dendrobatidis kills amphibians. To investigate the pathology of chytridiomycosis, blood samples were collected from uninfected, aclinically infected and clinically diseased amphibians and analyzed for a wide range of biochemical and hematological parameters. Here, we show that green tree frogs Litoria caerulea with severe chytridiomycosis had reduced plasma osmolality, sodium, potassium, magnesium and chloride concentrations. Stable plasma albumin, hematocrit and urea levels indicated that hydration status was unaffected, signifying depletion of electrolytes from circulation rather than dilution due to increased water uptake. We suggest that B. dendrobatidis kills amphibians by disrupting normal epidermal functioning, leading to osmotic imbalance through loss of electrolytes. Determining how B. dendrobatidis kills amphibians is fundamental to understanding the hostpathogen relationship and thus the population declines attributed to B. dendrobatidis. Understanding the mechanisms of mortality may also explain interspecific variation in susceptibility to chytridiomycosis. KEY WORDS:Amphibian declines · Chytridiomycosis · Batrachochytrium dendrobatidis · Pathogenesis · Mortality · Osmoregulation Resale or republication not permitted without written consent of the publisherDis Aquat Org 77: [113][114][115][116][117][118] 2007 Amphibian skin is well studied due to its unique functions (Deyrup 1964, Heatwole & Barthalmus 1994, Jorgensen 1997. The integument is a site of regulated transport for water, ions (electrolytes) and respiratory gases (Deyrup 1964, Heatwole & Barthalmus 1994, Jorgensen 1997. Permeability of frog skin varies over the body surface of an individual and also among species (Deyrup 1964, Heatwole & Barthalmus 1994. In some species osmotic permeability is greatest in an area of ventral integument commonly referred to as the pelvic patch (Czopek 1965, Baldwin 1974, Word & Hillman 2005, where there is dense cutaneous vasculature (Czopek 1965). Concomitantly, Batrachochytrium dendrobatidis occurs more commonly and at higher density in the ventral integument of infected frogs (Berger et al. 2005b, Puschendorf & Bolaños 2006. B. dendrobatidis grows within the keratinized cells of the superficial epidermis and causes irregular skin sloughing, hyperplasia and hyperkeratosis (Berger et al. 1998, 2005b, 2007. Other pathological changes including cytoplasmic degeneration and vacuolation in scattered cells have been observed by light and electron microscopy, but these changes are not usually severe (Berger et al. 2007). Thus, it is unclear how a superficial skin infection kills frogs.The aim of this research was to investigate pathogenesis in amphibians with chytridiomycosis. We evaluated changes in physiological parameters...

ABSTRACT. A total of 104 farmed turtles (102 Chelonia mydas and 2 Eretmochelys inlbricata) were examined for signs of chnical disease. They were obtained from the Torres Strait where they were housed in 250 1 fibreglass tanks and 50 1 plasbc basins and fed a diet of fish by islanders. Altogether, 28 diseases were diagnosed including 1 2 bactenal, 4 parasitic and 4 nutritional diseases. Less common were those of genetlc and environmental origin. Skin lesions due to biting (traumatic ulcerative dermatitis) were almost universal in farmed turtles. They were concentrated on the tips and trailing edges of the front and rear flippers and also on the neck and tail as well as the axillary and inguinal regions. Morb~dity and mortality rates of 100 and 30 %, respectively, were recorded in the first month of life. Juveniles and yearlings rarely succumbed to the disease. Cultures of lesion material yielded a variety of bacteria VIZ Vibrio alg~nolyticus, Pseudomonas fluorescens, Flavobacteriurn sp., Micrococcus sp. and Bacillus sp. Ulcerative stomatitis was the most important bacterial disease of farmed turtles after traumatic ulcerative dermatitis. It occurred as an epizootic in hatchlings 5 to 8 wk old. A plug of caseopurulent material in the oral cavity was usually the first overt sign of the disease. Debridement somebmes caused bleeding, indicating the presence of false membranes. Obstructive rhinltis and pneumonia were complications of the original condition. Turtles with these diseases showed loss of equilibrium and laboured respiration. Plugs of caseous material were lodged in the tracheahronchi and/or external nares. Focal pneumonia was characterised by nodular lesions in the apical or medial portion of the lung. Microscopic sections and cultures showed bacteria were mainly responsible. V. alginolyticus, Aeromonas hydroph~la, Flavobacterium sp. and Pseudomonas sp. were isolated from the upper and lower respiratory tract as well as the oral cavity. Fungal isolates viz PenicilLium sp., Paecilornyces sp., Fusarium sp. and Rhodotorula sp. were of secondary importance. Acid fast bacilli (Mycobacterium sp.) were seen in the lungs of 2 farmed turtles but were not isolated. Salmonellosis was diagnosed on only one occasion, when Salmonella enteritidis was isolated from the liver of a juvenile turtle. Eye lesions (keratoconjunctivitis -ulcerative blepharitis) were caused by rubbing against the side of the tank. Adenitis (salt-secreting gland infection) resulted from the introduction of forceps into the duct leading from the posterior orbit. Peritonitis was an extension of ulcerative shell disease. Pseudomonas spp. and Flavobacterium spp. were common to the last 3 hseases. Septicaemia-toxaemia was secondary to chronic bacterial and parasitic infections. V. alginolyticus, A. hydrophila and Flavobacterium sp. were isolated from the heart blood and caused toxic changes in the heart and kidneys. V. alginolyticus was cultured from a case of ulcerative shell disease and osteomyelitis. Gastritis-serositis syndrome was the most importa...

Abstract. Pythiosis (204 cases, 77%), basidiobolomycosis (48 cases, 18%), and conidiobolomycosis (14 cases, 5%) were diagnosed morphologically from 266 horses with phycomycosis. All lesions were cutaneous ulcerative granulomas and three horses with pythiosis had metastatic lesions in regional lymph nodes. Lesions of pythiosis contained characteristic yellow, coral-like coagula and had a fibrotic surface containing sinus tract openings. Basidiobolomycosis was characterized by infrequent small yellow coagula and a yellow line of fungal invasion beneath an edematous surface. Lesions of conidiobolomycosis had numerous small coagula and a nasal location. There were minor differences in inflammatory cell populations within the granulomatous lesions. Most differences were associated with coagula size and fungal morphology. Coagula were composed of collagen, fibrin, cellular debris, degranulated and whole eosinophils and hyphae. Histochemistry revealed no major differences among the three diseases. Pythium sp hyphae were 2.6 to 6.4 pm in diameter, had thick walls, and occasionally were septate. Basidiobolus haptosporus hyphae were 5.1 to 20.5 pm in diameter, had thin walls, and commonly were septate. Conidiobolus coronatus hyphae were 5.1 to 12.8 pm in diameter, had thin walls, and commonly were septate. A perihyphal eosinophilic cuff (Splendore-Hoeppli phenomenon) with a radius of up to 20 pm was associated with the latter two fungi. Ultrastructurally, Pythium sp was composed of a thick, single density cell wall while B. haptosporus and C. coronatus had thin, double-layered cell walls.