Jean A. Paré

Pathogenicity of the Chrysosporium anamorph of Nannizziopsis vriesii for veiled chameleons (Chamaeleo calyptratus)

Veiled chameleons (Chamaeleo calyptratus) were experimentally challenged with the fungus Chrysosporium anamorph of Nannizziopsis vriesii (CANV). Chameleons were exposed to conidia in their captive environment, or were inoculated by direct application of a conidial suspension inoculum on intact and on abraded skin. The CANV induced lesions in all experimental groups and was recovered from infected animals, fulfilling Kochs postulates and confirming that it may act as a primary fungal pathogen in this species of reptile. A breach in cutaneous integrity, as simulated by mild scarification, increased the risk of infection but was not required for the CANV to express pathogenicity. Initial hyphae proliferation occurred in the outer epidermal stratum corneum, with subsequent invasion of the deeper epidermal strata and dermis. A spectrum of lesions was observed ranging from liquefactive necrosis of the epidermis to granulomatous inflammation in the dermis. CANV dermatomycosis appears to be contagious and can readily spread within a reptile collection, either directly through contact with infective arthroconidia or indirectly via fomites. Dense tufts of arthroconidiating hyphae were demonstrated histologically on the skin surface of many animals that developed dermatomycosis, and these arthroconidia may act as infective propagules involved in the transfer of disease between reptiles.

Cutaneous Mycobiota of Captive Squamate Reptiles with Notes on the Scarcity of Chrysosporium Anamorph of Nannizziopsis vriesii

ABSTRACT The Chrysosporium anamorph of Nannizziopsis vriesii (CANV) is a fungus that has been implicated in several recent cases of reptile dermatomycoses. A survey was conducted to investigate whether this fungus was present on the skins of healthy squamate reptiles. Skin was collected as aseptically as possible from actively shedding lizards (n = 36) or from freshly shed snake exuvia (n = 91) and placed on fungal culture media for selective recovery of cycloheximide-tolerant fungi. The CANV was cultured from only one animal, an African rock python, Python sebae. Fungi belonging to 50 genera were identified from 127 reptiles: Aspergillus spp., Penicillium spp., and Paecilomyces lilacinus were most frequently isolated. Keratinophilic fungi isolated from reptiles did not belong to zoophilic or anthropophilic species, inferring that the potential for acquisition of dermatophytosis from handling squamate reptiles is low.

Fungal diseases of amphibians: an overview.

Clinicians should be familiar with the most common fungal diseases of amphibians. Because lesions in mycotic diseases are nonspecific, a diagnosis cannot be established solely on the basis of clinical presentation. Bacterial, mycobacterial, chlamydial, and parasitic infections, and toxic or environmental conditions may mimic mycotic disease to various extents. Furthermore, mycoses may be masked by overwhelming secondary bacterial infection and therefore remain undiagnosed. Skin scrapings, impression smears, biopsies, and fungal culture are all useful tools in confirming or dismissing a diagnosis of mycosis. Whenever possible, an effort should be made to forward samples and biopsies for culture to appropriate laboratories. Providing the laboratory with a tentative etiologic diagnosis may allow for specific selection of more specific agars and culture conditions and maximize the chances of recovering the fungus from lesions. Identification to species level should also be encouraged, if progress is to be made in the understanding of mycoses in amphibians. The morphology of an isolate should be consistent with the microscopic features of the fungus in histological sections of affected tissues, if it is to be firmly incriminated as the cause of disease. A complete necropsy should be conducted on animals that die or are found dead, and, ideally, isolates from confirmed cases of fungal infection should be deposited in scientific collections, so that they are available for later studies. In addendum, readers should be aware that there is recent evidence to suggest that at least some published cases of amphibian basidiobolomycosis were in fact cases of chytridiomycosis [38], and therefore the validity of basidiobolomycosis as a disease entity in amphibians may be revisited in the years to come.

Thelebolus microsporus Mycelial Mats in the Trachea of Wild Brown Skua (Catharacta antarctica lonnbergi) and South Polar Skua (C. maccormicki) Carcasses

Sixteen brown skuas (Catharacta antarctica lonnbergi) and seven South Polar skuas (C. maccormicki) were found dead near Boekella Lake, Hope Bay, Antarctica, in February 1997. Postmortem examination revealed conspicuous caseous, deep yellow fungal/mycelial mats or cores in the trachea of nine of 19 carcasses that were examined. These mycelial cores, highly suggestive of aspergillomas, completely occluded the tracheal lumen in four of these nine carcasses. Thelebolus microsporus, a psychrophilic ascomycetous fungus commonly isolated from skua dung and skua nesting material, was isolated in pure culture from these tracheal plugs. Awareness of pseudolesions resulting from Thelebolus microsporus profuse postmortem growth in the trachea of dead skuas will minimize potential confusion with aspergillosis when investigating causes of epornithics in Antarctica.

An Overview of Reptile Fungal Pathogens in the Genera Nannizziopsis, Paranannizziopsis, and Ophidiomyces

Abstract Two recent molecular analyses of morphologically similar fungal isolates formerly grouped under the appellation “Chrysosporium anamorph of Nannizziopsis vriesii (CANV) complex” led to major taxonomic revisions and revealed new insights into the biology of these reptile pathogens. All CANV-complex isolates differed from N. vriesii and were assigned to 16 species, either within Nannizziopsis or within the new genera Paranannizziopsis and Ophidiomyces, and 14 of these species were newly described. From these revisions, a trend in host specificity clearly emerged that was not previously apparent. Nannizziopsis now includes nine species associated with chamaeleonid, gekkonid, cordylid, teiid, agamid, and iguanid lizards; crocodiles; and human hosts. Paranannizziopsis includes four species that infect squamates and tuataras. Ophidiomyces, with the single species Ophidiomyces ophiodiicola (formerly Chrysosporium ophiodiicola), is only associated with terrestrial or semiaquatic snakes. Nannizziopsi guarroi (formerly Chrysosporium guarroi) is the main causal agent of yellow fungus disease in captive bearded dragons (Pogona vitticeps), and O. ophiodiicola is the cause of mycoses in captive snakes and of snake fungal disease, an emergent global threat to populations of endangered wild snakes. Histopathology, polymerase chain reaction assays, and culture are crucial for confirming a diagnosis of fungal infection in reptiles; however, because fungal identification based on morphologic and physiologic features alone is difficult, sequencing should be sought to speciate reptile fungal isolates. Information gathered from PCR assays and molecular speciation will help in outlining pathogenic potential and contagion risks associated with each of these newly recognized fungal species and allow for a more comprehensive understanding of the ecology, distribution, and host range of these pathogens.

Long-term oral clarithromycin administration in chelonians with subclinical Mycoplasma spp. infection

Abstract Choanal swabs were collected three times at 2 wk intervals from 17 asymptomatic captive chelonians, eight Forstens tortoises (Indotestudo forstenii) and nine Sulawesi forest turtles (Leucocephalon yuwonoi), to document individual Mycoplasma spp. shedding patterns. Four of the Forstens tortoises and six of the Sulawesi forest turtles tested positive repeatedly for Mycoplasma spp. DNA using a PCR assay. Clarithromycin, a macrolide antibiotic, was administered orally to all animals at 20 mg/kg every 2 to 3 days for a total of 90 days. While no adverse effects were noted, this extended 3 month long course of clarithromycin failed to suppress Mycoplasma spp. shedding in all but one of the 10 Mycoplasma spp. PCR-positive animals.