Batrachochytrium dendrobatidis infection and treatment in the salamanders Ambystoma andersoni , A . dumerilii and A . mexicanum

B dendrobatidis (Bd; Longcore et al., 1999) is a major fungal pathogen known to infect all orders of amphibian (Gower et al., 2013) and is a driver of population declines (Bosch et al., 2001; Lips et al., 2006; Briggs et al., 2010; Scheele et al., 2017). The recently described congener B. salamandrivorans (Bsal; Martel et al., 2013) also causes disease and its spread is a cause for major concern (Martel et al., 2014; Richgels et al., 2016; Spitzen-van der Sluijs 2016; Laking et al., 2017). Bsal is thought to be less cosmopolitan than the globally distributed Bd (Fisher et al., 2009; Sabino-Pinto et al., 2016); however, surveys of captive and free-living populations are far from comprehensive. In captivity, a variety of chemical treatments as well as heat therapy (27-37 ̊C) have been used to treat the chytrid infections caused by both agents (e.g. Berger et al., 2004; Bowerman et al., 2010; Chatfield and RichardsZawacki 2011; Martel et al., 2011; Woodhams et al., 2003, 2012; Brannelly et al., 2012; Blooi et al., 2015a; b). However, urodelan amphibians tend to exhibit low tolerances to elevated temperatures (e.g. Liu et al., 2006; Bury, 2008), which often precludes heat treatment as a viable method to clear Bd infection. It is therefore imperative that the efficacy of other treatment options is tested. Successful therapy using itraconazole has been documented in numerous amphibian species from all three orders (Forzan et al., 2008; Tamukai et al., 2011; Brannelly et al., 2012; Rendle et al., 2015), but different species respond differently to the drug. Itraconazole toxicosis has been reported in some amphibian species treated at ‘routine’ doses of the drug (Garner et al., 2009; Woodhams et al., 2012). It has therefore been recommended to record the effects of Bd on host animals and to develop and test protocols for treating this widespread pathogen in a variety of species of amphibian (Woodhams et al., 2012). We present data following Bd diagnosis and subsequent treatments of 40 Ambystoma dumerilii, 26 A. mexicanum and 10 A. andersoni in captivity (see Supplementary Materials for details). Animals were maintained according to the protocols outlined in Table 1 at the Zoological Society of London (ZSL), Chester Zoo (CZ), Parc de Thoiry (PT) and a private breeder in the UK (PB). Salamanders were sampled initially and post treatment (see Table 1) for Bd/Bsal screening by swabbing dorsum, In order to better understand the impacts and treatment of infection with Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) it is important to document host species, the effect of infection and response to treatment protocols. Here we report asymptomatic Bd infection detected through duplex qPCR screening of three Mexican ambystomatid salamanders; Ambystoma andersoni, Ambystoma dumerilii and Ambystoma mexicanum at three zoo collections, and A. andersoni and A. mexicanum in a private collection. Bsal was tested for but not detected. We also report the effectiveness and side effects of five treatment protocols in these species. Using the antifungal agent itraconazole, A. dumerilii were cleared of infection without side-effects using the granulated preparation (Sporanox). Morbidity and mortality occurred when A. dumerilii and A. andersoni were treated using a liquid oral preparation of the itraconazole (Itrafungol); infection was successfully cleared in surviving specimens of the latter species. Ambystoma mexicanum was successfully cleared without any side-effects using Itrafungol. Mortality and morbidity were likely caused by toxic effects of some component on the liquid preparation of itraconazole, but aspects of water quality and husbandry cannot be ruled out.