amphibian chytridiomycosis: strategies for captive management … · 2018-07-24 · amphibian...

Int. Zoo Yb. (2007) 41: 85–95

DOI:10.1111/j.1748-1090.2007.00010.x

Amphibian chytridiomycosis: strategies for captivemanagement and conservation

S. YOUNG, L. BERGER & R. SPEAREAmphibian Disease Ecology Group, School of Public Health, Tropical Medicine andRehabilitation Sciences, James Cook University, Townsville Qld 4811, AustraliaE-mail: [email protected]

Dramatic declines and extinctions of amphibian specieshave occurred worldwide over the last three decadesowing to the introduction of chytridiomycosis. This em-erging infectious disease is caused by the chytrid fungusBatrachochytrium dendrobatidis, a virulent water-bornepathogen of many amphibian species. It has causedepidemic waves of high mortality as it spread throughsusceptible wild populations in Australia, North, Centraland South America, and New Zealand, and is nowendemic in surviving populations in these continentsand in Europe and Africa. The prevalence of chytridio-mycosis in the international amphibian trade is high andimport of infected frogs into zoos has caused diseaseepidemics in established amphibian collections. Manage-ment of disease spread requires effective national andinternational quarantine and control strategies. AlthoughB. dendrobatidis is susceptible to a range of commonly useddisinfectants, there is no universally effective treatmentregime for infected amphibians. Zoological institutions canplay a key role in preventing pathogen spread betweencaptive facilities, and in disease surveillance, captive-breed-ing and reintroduction programmes, to limit the impact ofthis formidable disease on wild amphibian populations.

Key-words: amphibian; Batrachochytrium dendrobatidis;captive management; chytridiomycosis; decline; disin-fection; frog; quarantine.

INTRODUCTION

Over 30% of amphibian species are threa-tened and at least 43% are experiencingpopulation declines worldwide (Stuart et al.,2004). Since 1980, rapid declines have beenreported in over 400 species, with just overhalf of these attributed to habitat degradationand to overexploitation. In at least 200 speciesdeclines were considered enigmatic, predo-minantly affecting stream-associated frogs inprotected forests and tropical montane habi-tats in the Neotropics and Australia, whereenvironmental problems were not detected

(Stuart et al., 2004). Many of these declineshave now been linked to the formi-dable emerging infectious disease chytridio-mycosis, caused by the amphibian chytridfungus Batrachochytrium dendrobatidis(Berger et al., 1998; Bosch et al., 2001; Lipset al., 2006; Schloegel et al., 2006). Chytri-diomycosis has been detected in at least144 species, over-represented by four anuranfamilies: Bufonidae, Hylidae, Myobatrachi-dae and Ranidae (Speare & Berger, 2005).

Chytridiomycosis has been recorded inwild amphibian populations in Australia,New Zealand, the Caribbean, Europe, Africa,and South, Central and North America(e.g. Berger et al., 1998; Bosch et al., 2001;Waldman et al., 2001; Muths et al., 2003;Hanselmann et al., 2004; Weldon et al., 2004;Lips et al., 2006; Schloegel et al., 2006).Epidemiological evidence supports thehypothesis that B. dendrobatidis originated inAfrica and subsequently spread from thatcontinent via the global trade in Africanclawed frog Xenopus laevis (Weldon et al.,2004). In Australia, B. dendrobatidis has beenassociated with dramatic frog populationdeclines and extinctions, particularly in thehigh-altitude rainforest areas of Queensland(Berger et al., 1998; Schloegel et al., 2006).

EFFECTS AND DETERMINANTS OFCHYTRIDIOMYCOSIS

Infection with B. dendrobatidis occursthrough waterborne zoospores that invadethe superficial keratinized epidermal layersof amphibian skin, causing hyperkeratosis,

REVIEW: AMPHIBIANS & CHYTRIDIOMYCOSIS: STRATEGIES FOR CAPTIVE MANAGEMENT 85

Int. Zoo Yb. (2007) 41: 85–95. c� The Authors. Journal compilation c� 2007 The Zoological Society of London

sloughing and erosions of the epidermis, andoccasional ulcerations, in post-metamorphicfrogs (Berger et al., 1998, 1999). Affectedfrogs may display discoloured and reddenedskin, abnormal posture, lethargy, anorexia,delayed response to stimuli, loss of rightingreflex, seizures and death (Nichols et al.,1998, 2001; Berger et al., 1999). The me-chanisms by which the pathogen causes deathare unknown, but may include toxin releaseor host osmoregulatory disruption secondaryto skin damage (Berger et al., 1998). Batra-chochytrium dendrobatidis can be carried inthe keratinized mouthparts of tadpoles, manyof which exhibit oral abnormalities, particu-larly jaw sheath depigmentation (Bergeret al., 1999; Fellers et al., 2001; Rachowicz& Vredenburg, 2004; Obendorf, 2005; Knapp& Morgan, 2006). Populations of wild tad-poles may have a high prevalence of infection(Fellers et al., 2001; Knapp & Morgan,2006). While tadpoles of most species studieddo not die from infection, experiments havedemonstrated a reduced growth rate andsmaller size at metamorphosis (Parris, 2004).Interestingly, infection with B. dendrobatidisin Cope’s gray tree frog Hyla chrysoscelistadpoles caused slower development onlywhen predators were present, demonstratingthe cumulative effect of stressors (Parris &Beaudoin, 2004).

Morbidity and mortality rates in post-metamorphic amphibians vary greatly amongspecies (Ardipradja, 2001; Nichols et al.,2001; Woodhams et al., 2003; Berger et al.,2004; Carey et al., 2006). Mortality ratesof up to 100% have been recorded duringexperimental transmission and natural out-breaks of B. dendrobatidis in susceptiblecaptive anuran species (Berger et al., 1998,2005; Ardipradja, 2001; Nichols et al., 2001).The Common green tree frog Litoria caeruleaand Great barred frog Mixophyes fasciolatushave been shown experimentally to be highlysusceptible host species (Ardipradja, 2001).Incubation times are generally between 18and 70 days, but may be shorter (Berger,2001; Nichols et al., 2001). Some speciescan survive infection, and apparently healthyamphibians may frequently carry light infec-

tions in the wild (Hanselmann et al., 2004;Retallick et al., 2004; McDonald et al.,2005). Introduction of B. dendrobatidis tonaıve susceptible populations has causedepidemics of high mortality. If populationssurvive, the pathogen persists and becomesendemic, with reduced mortality rates and,in some cases, recovery (McDonald et al.,2005). This suggests that there is selection forhost resistance against the disease.

Experimentally, the fungus has been shownto persist and survive in environmentalsamples, independent of its host, for vary-ing periods (Johnson & Speare, 2003,2005). Suspected mechanisms of spread ofB. dendrobatidis include movement throughwater bodies and via surface water duringprecipitation, movement of individual in-fected amphibians and translocation onfomites and vectors, such as moist substrateor possibly birds (Speare et al., 2001;Johnson & Speare, 2003, 2005). The role ofalternative hosts in disease transmission iscurrently being investigated.

Survival and growth of the chytrid fungusis temperature dependent, the optimal rangebeing 17–25 1C (Piotrowski et al., 2004).Batrachochytrium dendrobatidis is highlysensitive to elevated temperatures, dying in4 hours at 37 1C (Berger, 2001; Johnson et al.,2003), and may be unable to persist outsidethe host when soil and water temperaturesexceed 25 1C for an extended period oftime. Host behaviour influences temperatureregimes experienced by the pathogen, andbasking to elevate host body temperaturemay play a curative role (Woodhams et al.,2003). Prevalence of infection and morta-lity rates in wild populations increase duringcooler months (Berger et al., 2004; Retallicket al., 2004; McDonald et al., 2005; Kriger& Hero, 2007). Experimentally, lower tem-peratures enhanced pathogen virulence inM. fasciolatus, with 100% mortality infrogs maintained at 17–23 1C, but only 50%at 27 1C (Berger et al., 2004). Woodhamset al. (2003) reported elimination of B. den-drobatidis by exposing infected Red-eyedtree frog Litoria chloris to 37 1C for two8 hour periods.

86 ANIMAL HEALTH AND CONSERVATION


DIAGNOSIS

Clinical signs of chytridiomycosis in post-metamorphic frogs manifest as abnormal be-haviour, neurological signs and skin lesions(Berger et al., 1998, 1999; Nichols et al.,1998, 2001) (Plate 1). However, these signsare non-specific and the disease cannot bediagnosed clinically. Diagnosis of chytridio-mycosis requires laboratory confirmation byroutine histological examination of skin sec-tions (e.g. toe clips), direct examination ofunstained skin smears, immunohistochemicalstaining of skin sections or polymerasechain reaction (PCR) assay of skin swabs(Berger et al., 1999, 2000, 2002; Berger,2001; Boyle et al., 2004) (Plates 2–5). Diag-nostic samples can be collected from live,frozen or preserved frogs. While all testscan accurately detect infection in sick frogswith severe chytridiomycosis, PCR assay ofskin swabs is recommended for screeninghealthy frogs owing to its increased sensitiv-ity and non-invasive nature (Table 1). Livetadpoles can be tested by collecting mouth-part swabs for PCR assay (Obendorf, 2005;A. Hyatt, unpubl. data). Visual inspectionof tadpole mouthparts may also be a reli-able indicator of B. dendrobatidis infection(Fellers et al., 2001; Rachowicz & Vreden-burg, 2004).

MANAGEMENT OFCHYTRIDIOMYCOSIS

Disinfection

Effective disinfection protocols are essentialfor the management of chytridiomycosis incaptive facilities and in the field. Batracho-chytrium dendrobatidis is susceptible to awide range of physical and chemical treat-ments (Johnson et al., 2003; Webb et al.,2007) (Table 2). It is highly sensitive totemperatures above 32 1C, with 100% mor-tality within 4 hours at 37 1C and within30minutes at 47 1C. Equipment can be disin-fected by immersion in hot water (60 1Cfor �5minutes). Desiccation is also effec-tive, but requires extended periods to ensurethat any water has evaporated completely. Acombination of heating and drying is recom-mended for some objects, such as clothingand equipment.

The pathogen is susceptible to severalchemical disinfectants, but concentration andtime of exposure are important (Johnsonet al., 2003; Webb et al., 2007). Recom-mended chemicals include the quaternaryammonium compound didecyl dimethyl am-monium chloride (DDAC), benzalkoniumchloride, Virkons, F10SC Veterinary Disin-fectants, TriGenes, ethanol and sodium

Plate 1. Captive-bred Great barred frog Mixophyes fasciolatus metamorph with naturally acquired chytridiomy-cosis in the terminal stages of disease. Note the depressed attitude, half-closed eyes and accumulations of sloughedskin over the body. Scale bar5 0 � 5 cm. Reprinted from Berger (2001).



hypochlorite (household bleach). Theseare particularly useful for disinfection ofequipment in the field, but care must be taken

to prevent environmental contamination.Although sodium hypochlorite is an effectivedisinfectant, it may damage some equipment.

Plate 2. Unstained wet mount of shedding skin from a Common green tree frog Litoria caerulea infected withBatrachochytrium dendrobatidis. Note the refractile round and oval sporangia. Most sporangia are empty but onecontains developing zoospores (arrow): E, epidermal cell; � 1000 magnification. Reprinted from Berger (2001).

Plate 3. Histological section of skin from a Common green tree frog Litoria caerulea heavily infected withBatrachochytrium dendrobatidis. Note the homogenous immature stage (I), larger multinucleate stages, zoosporangiumwith discharge tube (D) containing zoospores, and empty zoosporangium after zoospores have discharged (arrow): E,epidermis. Stained with haematoxylin and eosin, � 1000 magnification. Reprinted from Berger (2001).



Treatment

Effective treatment protocols for chytri-diomycosis are necessary to ensure success

of captive-breeding programmes for threa-tened species and to reduce risks associatedwith amphibian movements. Infected tad-poles survive and remain at sites after

Plate 4. Live cultured Batrachochytrium dendrobatidis sporangia. The infective zoospores form internally and thenescape by swimming out through the discharge tubes when the plugs dissolve. Scale bar5 20 mm. Reprinted fromBerger (2001).

Plate 5. Scanning electron micrograph of a Batrachochytrium dendrobatidis zoosporangium on agar releasing azoospore through a long discharge tube. Scale bar5 10 mm. Reprinted from Berger (2001).

DIAGNOSTIC TESTUNSTAINED SKINSCRAPINGS/SMEARS

HISTOLOGYOF SKIN SECTIONS

IMMUNOSTAININGOF SKIN SECTIONS

PCR ASSAYOF SKIN SWABS

Complexity and costof preparation

11 21 31 41

Resources required 11 21 31 51Ease of interpretation 11 21 31 51Sensitivity 21 21 31 51Use for healthy frogs Limited use Limited use Limited use Very useful

Table 1. Comparison of the characteristics of diagnostic tests for amphibian chytridiomycosis. All four methodsof diagnosis are useful, but each has various advantages and disadvantages. Note that frogs with clinically severedisease typically have very heavy Batrachochytrium dendrobatidis infections and highly sensitive tests are notrequired for diagnosis: 11 5 lowest, 51 5highest; PCR, polymerase chain reaction. Adapted from AustralianGovernment Department of the Environment and Heritage (2006) and Berger et al. (2007).



adults have declined or disappeared follow-ing an outbreak of chytridiomycosis. Treat-ment of tadpoles collected from thesesites would enable an emergency responseto mortality and declines in threatened spe-cies through captive rearing of tadpoles andthrough reintroduction. Effective treatmentwould also prevent pathogen spread duringtranslocation of amphibians between wildand captive populations (Australian Govern-ment Department of the Environment andHeritage, 2006). To date, no treatments havebeen consistently effective across species.

Itraconazole has been used successfullyboth orally (2–13mgkg� 1 daily for 9–28days)and via shallow immersion (0.01% suspen-sion for 5minutes daily for 11 days) to treatsome adult amphibians (Taylor et al., 1999;Nichols & Lamirande, 2000; Taylor, 2001).A commercial solution of malachite green(0.1mg litre� 1) and formaldehyde (25 p.p.m.)(Formalite IIIs) effectively treated Africanclawed frog Xenopus tropicalis (Parker et al.,2002), but malachite green can cause devel-opmental deformities and is therefore notrecommended for use in threatened species.Although temperature elevation to 37 1C waseffective in treating L. chloris (Woodhamset al., 2003), this treatment has not workedin other species (G. Marantelli, unpubl. data).Furthermore, some species may not toleratethese high temperatures. Itraconazole, fluco-nazole and F10SC Veterinary Disinfectants

baths for tadpoles were either ineffective ortoxic (Marantelli et al., 2000; B. McMeekin,unpubl. data). Treatment of water with

terbinafine hydrochloride (2–4mg litre� 1 for7 days) appears to be non-toxic to tadpolesand its efficacy in eliminating infection iscurrently being investigated (B. McMeekin,unpubl. data).

Quarantine

Routine quarantine procedures are critical forcontrolling chytridiomycosis in captivity, inthe field and during translocations. Infectedfrogs may appear clinically normal and theirtransport internationally has been implicatedin disease spread. There is a high prevalenceof chytridiomycosis in the international am-phibian trade including the pet trade (Bergeret al., 1999; Cunningham et al., 2005),the scientific trade (e.g. Weldon et al., 2004),the food trade (e.g. Mazzoni et al., 2003;Hanselmann et al., 2004), the ornamentaltrade (Daszak et al., 1999) and the introduc-tion of frogs into zoological collections(Nichols et al., 1998, 2001; Pessier et al.,1999; Banks & McCracken, 2002; Schloegelet al., 2006). Infected frogs imported intozoos have caused epidemics of chytridiomy-cosis in established amphibian collections,but few of these cases have been published(Nichols et al., 1998; Pessier et al., 1999).This may reflect potential problems withquarantine and hygiene procedures withinzoological collections.

Amphibians should be maintained in quar-antine as individuals in separate containersfor at least 2months, whether moving be-tween field sites, captive collections or

DISINFECTANT CONCENTRATION EXPOSURE TIME

Ethanol 70% 1minuteVirkons 1mgml� 1 1minuteBenzalkonium chloride 1mgml� 1 1minuteSodium hypochlorite 1% 1minuteDidecyl dimethyl ammonium chloride 1:1000 dilution 30 secondsF10SC Veterinary Disinfectants 1:1000 dilution 1minuteTriGenes 1:5000 dilution 1minuteComplete drying – 3 hours or moreHeat 60 1C 5minutes

Table 2. Disinfection methods suitable for killing Batrachochytrium dendrobatidis, showing minimum effectiveconcentrations and exposure times. From Johnson et al. (2003) and Webb et al. (2007).



countries. During quarantine, individualsshould be regularly examined for signs ofdisease and a thorough necropsy must beperformed on any animals that die during thequarantine period (Daszak et al., 2001;Lynch, 2001). Published protocols suggesttemperature during quarantine should bemaintained between 17 and 23 1C to increasethe chance of infection becoming clinicallyapparent (Lynch, 2001). However, owing tothe sensitivity of B. dendrobatidis to elevatedtemperatures and the high sensitivity of thePCR assay, the authors recommend holdingheat-tolerant species at the maximum tempera-ture they can tolerate, and collecting skinswabs for PCR assay on arrival and 7weekspost-arrival.

Important hygiene practices include wear-ing disposable gloves and changing glovesbetween enclosures, disinfection of equip-ment between use, attending to animals in aconsistent order starting with threatened spe-cies and those least likely to be infected, useof automated husbandry systems and disin-fection of water used in enclosures beforedisposal (Marantelli & Berger, 2000; Lynch,2001). Adhering to quarantine guidelines canprevent transmission of chytridiomycosis be-tween frogs housed in close proximity, buteven small numbers of zoospores are highlyinfectious and great care must be taken toprevent contamination of groups of animalswith drops of water.

Hygiene protocols for fieldwork should bestringently followed, including disinfectionof footwear and equipment between sites, theuse of disposable gloves and plastic bags forhandling frogs and disinfection of equipmentbetween frogs. Adults should never be heldtogether in the same container, and tadpolesfor release should never be held with batchesof tadpoles from other sites, even if theyoriginate from a common water body (NewSouth Wales National Parks and WildlifeService, 2000; Speare et al., 2004).

Control

‘Infection of amphibians with chytrid fungusresulting in chytridiomycosis’ was listed as a

‘key threatening process’ in Australia in July2002 under the Environment Protection andBiodiversity Protection Act. This led to thedevelopment of a Threat Abatement Plan,which aims to minimize the impact of chy-tridiomycosis on amphibian populationsthrough prevention of pathogen spread, recov-ery of at-risk threatened species, control ofinfection, education and coordination of man-agement activities (Australian GovernmentDepartment of the Environment and Heritage,2006). Effective management of chytridiomy-cosis requires national surveillance to determineaccurately disease distribution, protection ofdisease-free populations, rapid detection of andresponse to new outbreaks, restriction of am-phibianmovements, implementation of nationalhygiene and quarantine protocols, and routinemonitoring of stock for chytridiomycosis.

Captive breeding can play a critical role inlimiting the impact of chytridiomycosis onwild amphibian populations by providingsupplemental numbers of threatened speciesfor restocking and research (Australian Gov-ernment Department of the Environment andHeritage, 2006). It may be possible to selectfor innate disease resistance by collectingtadpoles from declining populations, breed-ing from individuals that survive metamor-phosis and restocking field sites with theirprogeny. Individuals must not be returnedto their point of origin unless they can beshown to be disease-free, and diagnosticscreening procedures must be implementedto ensure this. Augmenting remnant popula-tions through restocking has been success-fully used in Australia with Corroboree frogPseudophryne corroboree and this strategyappears to have played an important role inslowing the decline of this Critically Endan-gered species (IUCN, 2006; G. Marantelli,unpubl. data). An intensive captive-breedingprogramme for the last remaining Wyomingtoad Bufo baxteri population in Wyomingprevented extinction and efforts to reintro-duce this species to the wild are under way(AmphibiaWeb, 2006). The success of thisprogramme was largely a result of earlyrecognition of the precarious status of wildpopulations, extensive collaborative captive-



breeding efforts involving government andzoological institutions, and habitat protectionthrough land purchase. The urgent need forcaptive-breeding programmes for a numberof other threatened species has been recog-nized but many of these programmes are intheir infancy owing to limited captive-breed-ing success.

Restocking of threatened species may in-crease their chance of survival when highmortality rates threaten to cause extinction.This strategy can increase the time availablefor a species to develop disease resistance andmaintain population numbers during adverseconditions that favour the pathogen. Captive-reared amphibians used for restocking mustbe kept disease-free, and restocking must beimplemented before the final population of aspecies is under threat, or extinction may notbe preventable (Australian Government De-partment of the Environment and Heritage,2006). This is demonstrated by the case ofSharp-snouted day frog Taudactylus acutir-ostris in Australia, where frogs and tadpoleswere transferred from the last remainingpopulation into captivity. As the wild popula-tion crashed from chytridiomycosis, the cap-tive specimens also died from the disease,resulting in extinction of the species (Banks& McCracken, 2002; Schloegel et al., 2006;Australian Government Department of theEnvironment and Heritage, 2007).

Batrachochytrium dendrobatidis continuesto spread through naıve populations in Pana-ma, causing severe declines and threateninglarge numbers of frog species (Lips et al.,2006). Emergency response to this situationhas involved moving as many individuals aspossible into captivity (B. Goodman, ‘Tostem widespread extinction, scientists airliftfrogs in carry-on bags’, New York Times, 6June 2006, http://www.nytimes.com/2006/06/06/science/06frog.html?ex=1307246400&en=7eadca40d157485d&ei=5088&partner=rssnyt&emc=rss), but without establishedcaptive-breeding programmes and treatmentand quarantine protocols, this strategy maynot be successful in preventing extinctions.Until successful treatments are identified,prevention of pathogen spread, captive breed-

ing for restocking well in advance of diseaseoutbreaks in the wild and captive rearing andbreeding from tadpoles to select for innateresistance are the most important strategies tolimit the impact of chytridiomycosis on wildpopulations.

FUTURE DIRECTIONS

Dedicated resources on a global scale must bemade available in zoological and other insti-tutions for captive breeding of threatenedspecies and for emergency response to popu-lation declines. Researching the natural his-tory and biology of these species in the wildand in captivity must be prioritized to enablecaptive-breeding success. To date, few cap-tive-breeding programmes for threatened spe-cies have been successful owing to a lack ofcritical knowledge about the species. Cap-tive-breeding programmes must be well-planned and implemented in advance of thethreat to survival of a species, and there mustbe extensive collaboration between partici-pating institutions worldwide. Althoughcryopreservation of amphibian semen hasbeen achieved, the large size and thick cap-sules of eggs and embryos make successfulfreezing unlikely (Sargent & Mohun, 2005).

Further research is needed to determineeffective treatments for tadpoles and adults,and whether selection for innate disease re-sistance is a feasible management strategy forboth captive and wild populations. Surveil-lance of amphibian populations must be co-ordinated nationally and internationally todetermine accurately the distribution of chy-tridiomycosis and to rapidly detect and re-spond to outbreaks (Australian GovernmentDepartment of the Environment and Heritage,2006). Increased efforts to educate the publicshould be undertaken to reduce diseasetransmission through human activity andthrough accidental translocation of infectedamphibians and other materials. Zoologicalinstitutions can play an important role insupporting these activities, both internallyand externally.

Finally, while zoos can play a key role incontributing to amphibian conservation,



maintaining threatened species in captivitymust be recognized as only a short-termsolution because of space limitations and theinability to maintain genetically viable popu-lations indefinitely. Resources must be madeavailable immediately to preserve and restorethe natural habitats of amphibians. Removingother significant threats to amphibians suchas habitat loss and degradation will maximizepopulation sizes and may assist in survivaland recovery from the impact of chytridio-mycosis. Habitat protection will ultimatelypreserve whole ecosystems, not just indivi-dual threatened species, and should be apriority in the global response to chytridio-mycosis.

For detailed information about chytridiomy-cosis, including diagnosis and management,see the Amphibian Disease Home Page: http://www.jcu.edu.au/school/phtm/PHTM/frogs/ampdis.htm

Some related amphibian conservation websites include:� AmphibiaWeb: http://www.amphibiaweb.org� Declining Amphibian Populations Task

Force: http://www.open.ac.uk/daptf/index.htm

� IUCN Global Amphibian Assessment:http://www.globalamphibians.org

� IUCN Species Survival Commission Con-servation Breeding Specialist Group:http://www.cbsg.org/amphibian/php

� World Association of Zoos and Aqua-riums: http://www.waza.org/conservation/campaigns21.php?view=campaigns&id=1

ACKNOWLEDGEMENTSWe wish to thank Robert Puschendorf for input regardingmanagement, and Bonnie McMeekin and Gerry Marantel-li for allowing us to use their unpublished treatment data.

PRODUCTS MENTIONED IN THE TEXTF10SC Veterinary Disinfectants: broad-spectrum mul-ti-purpose disinfectant and sanitizer, manufactured byHealth and Hygiene Pty Ltd, PO Box 34, Sunninghill,2157, South Africa.Formalite IIIs: aquarium antimicrobial in-water treat-ment, manufactured by Aquatronics, PO Box 2457,Oxnard, CA 93034, USA.TriGenes: broad-spectrum disinfectant concentrate,manufactured by MediChem International (Manufactur-

ing) Ltd, Unit 3, Stalham Business Centre, RushendenRd, Queenborough, Kent ME11 5HE, UK.Virkons: broad-spectrum disinfectant effective againstviruses, bacteria and fungi, manufactured by AntecInternational Ltd, Sudbury, Suffolk CO10 2XD, UK.

DIAGNOSTIC SERVICES OFFERING CHYTRIDPCR TESTINGAustralian Animal Health Laboratory: CSIRO Divisionof Livestock Industries, 5 Portarlington Road, GeelongVIC 3220, Australia. Contact Alex Hyatt ([email protected]) before sample submission.Institute of Zoology: Zoological Society of London, Re-gent’s Park, London NW1 4RY, UK. Contact Matt Perkins([email protected]) and Clyde Hutchinson([email protected]) before sample submission.Pisces Molecular: 5311 Western Avenue, Suite E,Boulder CO 80301, USA. Contact John Wood ([email protected]) before sample submission.

REFERENCESAMPHIBIAWEB (2006): Information on amphibian biologyand conservation. Berkeley, CA: AmphibiaWeb. http://www.amphibiaweb.org/declines/zoo.index.htmlARDIPRADJA, K. (2001): A study of resistance towards theemerging pathogen Batrachochytrium dendrobatidis infour species of Australian frogs. BSc honours disserta-tion, University of Melbourne, Australia.AUSTRALIAN GOVERNMENT DEPARTMENT OF THE ENVIRON-

MENT and HERITAGE (2006): Threat abatement plan forinfection of amphibians with chytrid fungus resulting inchytridiomycosis: background document. Canberra:Commonwealth of Australia. http://www.deh.gov.au/bio-diversity/threatened/publications/tap/chytrid/index.htmlAUSTRALIAN GOVERNMENT DEPARTMENT OF THE ENVIRON-

MENT AND HERITAGE (2007): Taudactylus acutirostris inspecies profile and threats database. Canberra: Com-monwealth of Australia. http://www.deh.gov.au/spratBANKS, C. & MCCRACKEN, H. (2002): Captive manage-ment and pathology of sharp-snouted day frogs, Taudac-tylus acutirostris, at Melbourne and Taronga zoos. InFrogs and the community, proceedings of the Brisbanesymposium: 94–102. Natrass, A. E. O. (Ed.). Brisbane:Queensland Frog Society.BERGER, L. (2001): Diseases in Australian frogs. PhD dis-sertation, James Cook University, Townsville, Australia.BERGER, L., SPEARE, R., DASZAK, P., GREEN, D. E.,CUNNINGHAM, A. A., GOGGIN, C. L., SLOCOMBE, R.,RAGAN, M. A., HYATT, A. D., MCDONALD, K. R., HINES,H. B., LIPS, K. R., MARANTELLI, G. & PARKES, H. (1998):Chytridiomycosis causes amphibian mortality associatedwith population declines in the rainforests of Australiaand Central America. Proceedings of the National Acad-emy of Sciences of the United States of America 95:9031–9036.BERGER, L., SPEARE, R. & HYATT, A. (1999): Chytrid fungiand amphibian declines: overview, implications andfuture directions. In Declines and disappearances ofAustralian frogs: 23–33. Campbell, A. (Ed.). Canberra:Environment Australia.



BERGER, L., SPEARE, R. & KENT, A. (2000): Diagnosis ofchytridiomycosis of amphibians by histological examina-tion. Zoos’ Print Journal 15: 184–190. http://www.jcu.edu.au/school/phtm/PHTM/frogs/histo/chhisto.htmBERGER, L., HYATT, A. D., OLSEN, V., HENGSTBERGER, S.G., BOYLE, D., MARANTELLI, G., HUMPHRIES, K. & LONG-

CORE, J. E. (2002): Production of polyclonal antibodies toBatrachochytrium dendrobatidis and their use in animmunoperoxidase test for chytridiomycosis in amphi-bians. Diseases of Aquatic Organisms 48: 213–220.BERGER, L., SPEARE, R., HINES, H., MARANTELLI, G., HYATT,A. D., MCDONALD, K. R., SKERRATT, L. F., OLSEN, V.,CLARKE, J. M., GILLESPIE, G., MAHONY, M., SHEPPARD, N.,WILLIAMS, C. & TYLER, M. J. (2004): Effect of season andtemperature on mortality in amphibians due to chytridio-mycosis. Australian Veterinary Journal 82: 31–36.BERGER, L., MARANTELLI, G., SKERRATT, L. F. & SPEARE, R.(2005): Virulence of the amphibian chytrid fungus Ba-trachochytrium dendrobatidis varies with the strain.Diseases of Aquatic Organisms 68: 47–50.BERGER, L., LONGCORE, J. E., SPEARE, R., HYATT, A. &

SKERRATT, L. F. (2007): Fungal diseases of amphibians. InAmphibian biology: conservation and decline. Heatwole,H. & Wilkinson, J. (Eds). Chipping Norton: SurreyBeatty Sons. (In press).BOSCH, J., MARTINEZ-SOLANO, I. & GARCIA-PARIS, M.(2001): Evidence of a chytrid fungus infection involvedin the decline of the common midwife toad (Alytesobstetricans) in protected areas of central Spain. Biologi-cal Conservation 97: 331–337.BOYLE, D. G., BOYLE, D. B., OLSEN, V., MORGAN, J. A. T.& HYATT, A. D. (2004): Rapid quantitative detection ofchytridiomycosis (Batrachochytrium dendrobatidis) inamphibian samples using real-time Taqman PCR assay.Diseases of Aquatic Organisms 60: 141–148.CAREY, C., BRUZGUL, J. E., LIVO, L. J., WALLING, M. L.,KUEHL, K. A., DIXON, B. F., PESSIER, A. P., ALFORD, R. A.& ROGERS, K. B. (2006): Experimental exposures ofboreal toads (Bufo boreas) to a pathogenic chytrid fungus(Batrachochytrium dendrobatidis). EcoHealth 3: 5–21.CUNNINGHAM, A. A., GARNER, T. W. J., AGUILAR-SANCHEZ,V., BANKS, B., FOSTER, J., SAINSBURY, A. W., PERKINS, M.,WALKER, S. F., HYATT, A. D. & FISHER, M. C. (2005):Emergence of amphibian chytridiomycosis in Britain.Veterinary Record 157: 386–387.DASZAK, P., BERGER, L., CUNNINGHAM, A. A., HYATT, A.D., GREEN, D. E. & SPEARE, R. (1999): Emerging infec-tious diseases and amphibian population declines. Emer-ging Infectious Diseases 5: 735–748.DASZAK, P., CUNNINGHAM, A. A. & HYATT, A. D. (2001):Draft guidelines for international translocation of amphi-bians with respect to infectious diseases. In Developingmanagement strategies to control amphibian diseases:decreasing the risks due to communicable diseases: 171–178. Speare, R. (Ed.). Townsville: School of PublicHealth and Tropical Medicine, James Cook University.http://www.jcu.edu.au/school/phtm/PHTM/frogs/adms/attach6.pdfFELLERS, G. M., GREEN, D. E. & LONGCORE, J. E.(2001): Oral chytridiomycosis in the mountain

yellow-legged frog (Rana mucosa). Copeia 2001(4):945–953.HANSELMANN, R., RODRIGUEZ, A., LAMPO, M., FAJARDO-RA-

MOS, L., AGUIRRE, A. A., KILPATRICK, A. M., RODRIGUEZ, J. P.& DASZAK, P. (2004): Presence of an emerging pathogen ofamphibians in introduced bullfrogs Rana catesbeiana inVenezuela. Biological Conservation 120: 115–119.IUCN (The World Conservation Union) (2006): Globalamphibian assessment. Gland and Cambridge: IUCN;Arlington, VA: Conservation International; Arlington,VA: NatureServe.JOHNSON, M. L. & SPEARE, R. (2003): Survival of Batra-chochytrium dendrobatidis in water: quarantine and dis-ease control implications. Emerging Infectious Diseases9: 922–925.JOHNSON, M. L. & SPEARE, R. (2005): Possible modes ofdissemination of the amphibian chytrid Batrachochy-trium dendrobatidis in the environment. Diseases ofAquatic Organisms 65: 181–186.JOHNSON, M. L., BERGER, L., PHILLIPS, L. & SPEARE, R.(2003): Fungicidal effects of chemical disinfectants, UVlight, desiccation and heat on the amphibian chytrid,Batrachochytrium dendrobatidis. Diseases of AquaticOrganisms 57: 255–260.KNAPP, R. A. & MORGAN, J. A. T. (2006): Tadpolemouthpart depigmentation as an accurate indicator ofchytridiomycosis, an emerging disease of amphibians.Copeia 2006(2): 188–197.KRIGER, K. M. & HERO, J.-M. (2007): Large-scale seaso-nal variation in the prevalence and severity of chytridio-mycosis. Journal of Zoology 271: 352–359.LIPS, K. R., BREM, F., BRENES, R., REEVE, J. D., ALFORD,R. A., VOYLES, J., CAREY, C., LIVO, L., PESSIER, A. P. &

COLLINS, J. P. (2006): Emerging infectious disease and theloss of biodiversity in a Neotropical amphibian commu-nity. Proceedings of the National Academy of Sciences ofthe United States of America 103: 3165–3170.LYNCH, M. (2001): Amphibian quarantine protocols:Melbourne Zoo. In Developing management strategiesto control amphibian diseases: decreasing the risks dueto communicable diseases: 179–183. Speare, R. (Ed.).Townsville: School of Public Health and Tropical Med-icine, James Cook University. http://www.jcu.edu.au/school/phtm/PHTM/frogs/adms/attach6.pdfMARANTELLI, G. & BERGER, L. (2000): Quarantine meth-ods for captive collections. In Getting the jump! onamphibian disease: conference and workshop compen-dium: 26. Moore, K. & Speare, R. (Eds). Cairns: Rain-forest CRC.MARANTELLI, G., BERGER, L. & MCINNES, K. (2000):Investigations into the treatment of Batrachochytriumin frogs and tadpoles. In Getting the jump! onamphibian disease: conference and workshop compen-dium: 27. Moore, K. & Speare, R. (Eds). Cairns: Rain-forest CRC.MAZZONI, R., CUNNINGHAM, A. A., DASZAK, P., APOLO, A.,PERDOMO, E. & SPERANZA, G. (2003): Emerging pathogenof wild amphibians in frogs (Rana catesbeiana) farmedfor international trade. Emerging Infectious Diseases 9:995–998.



MCDONALD, K. R., MENDEZ, D., MULLER, R., FREEMAN, A.B. & SPEARE, R. (2005): Decline in the prevalence ofchytridiomycosis in upland frog populations in NorthQueensland, Australia. Pacific Conservation Biology 11:114–120.

MUTHS, E., CORN, P. S., PESSIER, A. P. & GREEN, D. E.(2003): Evidence for disease-related amphibian declinein Colorado. Biological Conservation 110: 357–365.NEW SOUTHWALES NATIONAL PARKS AND WILDLIFE SERVICE(2000): Threatened species management, InformationCircular 6, hygiene protocol for the control of disease infrogs. New South Wales: National Parks and WildlifeService.NICHOLS, D. K. & LAMIRANDE, E. W. (2000): Treatment ofcutaneous chytridiomycosis in blue-and-yellow poisondart frogs (Dendrobates tinctorius). In Getting the jump!on amphibian disease: conference and workshop com-pendium: 51. Moore, K. & Speare, R. (Eds). Cairns:Rainforest CRC.NICHOLS, D. K., PESSIER, A. P. & LONGCORE, J. E. (1998):Cutaneous chytridiomycosis: an emerging disease? Pro-ceedings of the American Association of Zoo Veterinar-ians 1998: 269–271.NICHOLS, D. K., LAMIRANDE, E. W., PESSIER, A. P. &

LONGCORE, J. E. (2001): Experimental transmission ofcutaneous chytridiomycosis in dendrobatid frogs. Jour-nal of Wildlife Diseases 37: 1–11.OBENDORF, D. L. (2005): Application of field and diag-nostic methods for chytridiomycosis in Tasmanian frogs.Birralee, Tasmania: Central North Field Naturalists Inc.http://www.deh.gov.au/biodiversity/invasive/publications/tasmanian-frogs.pdfPARKER, J. M., MIKAELIAN, I., HAHN, N. & DIGGS, H. E.(2002): Clinical diagnosis and treatment of epidermalchytridiomycosis in African clawed frogs (Xenopustropicalis). Comparative Medicine 52: 265–268.PARRIS, M. J. (2004): Hybrid response to pathogeninfection in interspecific crosses between two amphibianspecies (Anura: Ranidae). Evolutionary Ecology Re-search 6: 457–471.PARRIS, M. J. & BEAUDOIN, J. G. (2004): Chytridiomycosisimpacts predator–prey interactions in larval amphibiancommunities. Oecologia 140: 626–632.PESSIER, A. P., NICHOLS, D. K., LONGCORE, J. E. & FULLER,M. S. (1999): Cutaneous chytridiomycosis in poison dartfrogs (Dendrobates spp.) and White’s tree frogs (Litoriacaerulea). Journal of Veterinary Diagnostic Investiga-tions 11: 194–199.PIOTROWSKI, J. S., ANNIS, S. L. & LONGCORE, J. E. (2004):Physiology of Batrachochytrium dendrobatidis, a chytridpathogen of amphibians.Mycologia 96: 9–15.RACHOWICZ, L. J. & VREDENBURG, V. T. (2004): Transmis-sion of Batrachochytrium dendrobatidis within and be-tween amphibian life stages. Diseases of AquaticOrganisms 61: 75–83.RETALLICK, R. W., MCCALLUM, H. & SPEARE, R. (2004):Endemic infection of the amphibian chytrid fungus in afrog community post-decline. Public Library of ScienceBiology 2: e351.

SARGENT, M. G. & MOHUN, T. J. (2005): Cryopreservationof sperm of Xenopus laevis and Xenopus tropicalis.Genesis 41: 41–46.SCHLOEGEL, L. M., HERO, J.-M., BERGER, L., SPEARE, R.,MCDONALD, K. & DASZAK, P. (2006): The decline of thesharp-snouted day frog (Taudactylus acutirostris): thefirst documented case of extinction by infection in a free-ranging wildlife species? EcoHealth 3: 35–40.SPEARE, R. & BERGER, L. (2005). Global distribution ofchytridiomycosis in amphibians. Accessed at: http://www.jcu.edu.au/school/phtm/PHTM/frogs/chyglob.htmSPEARE, R., ALFORD, R., APLIN, K. BERGER, L. CULLEN, B.,DOVEY, L., HALLIDAY, T., HINES, H., HYATT, A., LYNCH, M.,MARANTELLI, G., MCDONALD, K., ORCHARD, S. & OWENS,L. (2001): Nomination for listing of amphibian chytri-diomycosis as a key threatening process under theEnvironment Protection and Biodiversity ConservationAct 1999. In Developing management strategies tocontrol amphibian diseases: decreasing the risks due tocommunicable diseases: 185–196. Speare, R. (Ed.).Townsville: School of Public Health and Tropical Med-icine, James Cook University.SPEARE, R., BERGER, L., SKERRATT, L. F., ALFORD, R.,MENDEZ, D., CASHINS, S., KENYON, N., HAUSELBERGER, K.& ROWLEY, J. (2004): Hygiene protocol for handlingamphibians in field studies. http://www.jcu.edu.au/school/phtm/PHTM/frogs/field-hygiene.pdfSTUART, S. N., CHANSON, J. S., COX, N. A., YOUNG, B. E.,RODRIQUES, A. S. L., FISCHMAN, D. L. & WALLER, R. W.(2004): Status and trends of amphibian declines andextinctions worldwide. Science 306: 1783–1786.TAYLOR, S. K. (2001): Mycoses. In Amphibian medicineand captive husbandry: 181–191. Wright, K. M. &Whitaker, B. R. (Eds). Malabar: Kreiger Publishing.TAYLOR, S. K., WILLIAMS, E. S., THORNE, E. T., MILLS, K.W., WITHERS, D. I. & PIER, A. C. (1999): Causes ofmortality of the Wyoming toad. Journal of WildlifeDiseases 35: 49–58.WALDMAN, B., VAN DE WOLFSHAAR, K. E., KLENA, J. D.,ANDJIC, V., BISHOP, P. J. & NORMAN, R. J. DE B. (2001):Chytridiomycosis in New Zealand frogs. Surveillance28: 9–11.WEBB, R., MENDEZ, D., BERGER, L. & SPEARE, R. (2007):Additional disinfectants effective against the amphibianchytrid fungus, Batrachochytrium dendrobatidis. Dis-eases of Aquatic Organisms 74: 13–16.WELDON, C. L., DU PREEZ, H., HYATT, A. D., MULLER, R.& SPEARE, R. (2004): Origin of the amphibian chytridfungus. Emerging Infectious Diseases 10: 2100–2105.WOODHAMS, D. C., ALFORD, R. A. & MARANTELLI, G.(2003): Emerging disease of amphibians cured by ele-vated body temperature. Diseases of Aquatic Organisms55: 65–67.

Manuscript submitted 28 September 2006;revised 12 January 2007; accepted 7 February2007



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