Chytridiomycosis, Amphibian Extinctions, and Lessons for the Prevention of Future Panzootics

Centre for Innovative Conservation Strategies, School of Environment, Griffith University, Gold Coast, QLD, Australia.
EcoHealth (Impact Factor: 2.27). 06/2009; 6(1):6-10. DOI: 10.1007/s10393-009-0228-y
Source: PubMed

ABSTRACT The human-mediated transport of infected amphibians is the most plausible driver for the intercontinental spread of chytridiomycosis, a recently emerged infectious disease responsible for amphibian population declines and extinctions on multiple continents. Chytridiomycosis is now globally ubiquitous, and it cannot be eradicated from affected sites. Its rapid spread both within and between continents provides a valuable lesson on preventing future panzootics and subsequent erosion of biodiversity, not only of amphibians, but of a wide array of taxa: the continued inter-continental trade and transport of animals will inevitably lead to the spread of novel pathogens, followed by numerous extinctions. Herein, we define and discuss three levels of amphibian disease management: (1) post-exposure prophylactic measures that are curative in nature and applicable only in a small number of situations; (2) pre-exposure prophylactic measures that reduce disease threat in the short-term; and (3) preventive measures that remove the threat altogether. Preventive measures include a virtually complete ban on all unnecessary long-distance trade and transport of amphibians, and are the only method of protecting amphibians from disease-induced declines and extinctions over the long-term. Legislation to prevent the emergence of new diseases is urgently required to protect global amphibian biodiversity.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The amphibian disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a major cause of worldwide amphibian declines and extinctions. Although several studies indicate that Bd prevalence and infection intensity vary seasonally, temporal variation of Bd at high-latitude sites, such as the northeastern USA, is still poorly characterized. We screened amphibians for Bd monthly at 2 study sites in New York State from April to October 2011 and used quantitative polymerase chain reaction (qPCR) to detect and quantify temporal variability in Bd infection prevalence and intensity. We found pronounced seasonal variation in both Bd infection prevalence and intensity at the community level, and our data indicate that this pattern is due to a few species (Lithobates catesbeianus, L. clamitans, and Notophthalmus viridescens) that drive temporal variability in disease dynamics. Amphibian body mass and sex were significant predictors of infection intensity but not infection prevalence. Understanding the temporal dynamics of Bd host-pathogen interactions provides important insight into regional, seasonal, and host-specific determinants of disease outbreaks. Further, our study elucidates the most relevant and informative timing for Bd surveys in temperate amphibian assemblages. Seasonal variation of infection dynamics suggests that Bd surveys from different sampling time points are not comparable, and summer surveys to evaluate chytridiomycosis may significantly underestimate Bd prevalence and intensity, leading to false conclusions about the severity of chytridiomycosis-induced amphibian mortality and population decline.
    Diseases of Aquatic Organisms 10/2014; 111(1). DOI:10.3354/dao02760 · 1.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Batrachochytrium dendrobatidis (Bd) is a fungal pathogen often responsible for amphibian declines worldwide. We report here survey on Bd in Papua New Guinea (PNG). The survey for Bd was conducted along a rainforest altitudinal gradient from Madang (50 m a.s.l.) to Mt. Wilhelm (3700 m a.s.l.). We swabbed 249 frogs of 63 native species at nine sites to quantify the number of Bd zoospore equivalents using real-time Syber Green Polymerase Chain Reaction (qPCR). We found no evidence for Bd. The lack of Bd may be due to 1) hot climate all year round inhibiting the spread of Bd in the entire lowland areas of PNG, 2) low number of non-native amphibian introductions to PNG such as Lithobates catesbeianus or Xenopus spp. or 3) the lack of invasive introductions by humans due to geographic isolation. While it is difficult to discern between these hypotheses, an effective quarantine should be devised to protect PNG from future disease outbreak. International assistance is needed in conservation education and research to assist the local scientists in monitoring and protecting these rich fauna from future Bd outbreaks.
    Herpetological Journal 02/2012; 22:183-186. · 1.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The international trade in amphibians is believed to have increased the spread of Batrachochytrium dendrobatidis (Bd), the fungal pathogen responsible for chytridiomycosis, which has caused a rapid decline in amphibian populations worldwide. We surveyed amphibians imported into Japan and those held in captivity for a long period or bred in Japan to clarify the Bd infection status. Samples were taken from 820 individuals of 109 amphibian species between 2008 and 2011 and were analyzed by a nested-PCR assay. Bd prevalence in imported amphibians was 10.3% (58/561), while it was 6.9% (18/259) in those in private collections and commercially bred amphibians in Japan. We identified the genotypes of this fungus using partial DNA sequences of the internal transcribed spacer (ITS) region. Sequencing of PCR products of all 76 Bd-positive samples revealed 11 haplotypes of the Bd ITS region. Haplotype A (DNA Data Bank of Japan accession number AB435211) was found in 90% (52/58) of imported amphibians. The results show that Bd is currently entering Japan via the international trade in exotic amphibians as pets, suggesting that the trade has indeed played a major role in the spread of Bd.
    Diseases of Aquatic Organisms 05/2014; 109(2):165-175. DOI:10.3354/dao02732 · 1.59 Impact Factor

Full-text (2 Sources)

Available from
May 29, 2014