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webwheeler
at Sat May 22 15:42:24 2010 [ Email Message ] [ Show All Posts by webwheeler ]
"Due to its recent, and largely simultaneous, recognition as a globally widespread pathogen, chytridiomycosis has been designated an emerging infectious disease (Daszak et al. 2003). Two hypotheses have been advanced to account for the emerging nature of disease caused by Bd; on one hand, the ‘novel pathogen hypothesis’ (NPH) states that Bd has recently spread into new geographic areas, and host species, as a result of the anthropogenically-mediated spread of Bd. On the other hand, the ‘endemic pathogen hypothesis’ (EPH) states that the emergence of chytridiomycosis has been caused by amphibian hosts becoming more susceptible to pre-existing infections as a consequence of changes in the environment.
The purpose of this review is not to weigh up the evidence for the NPH versus the EPH; this was ably undertaken by Rachowicz et al. (2005). Ours, and other, research show that both hypotheses contribute to explaining the current pandemic. The NPH receives support from the fact that epidemic fronts of introduction have been identified (Lips et al. 2006), that globally-recovered isolates of Bd show little genetic diversity suggestive of a recent expansion from a point-origin (Morehouse et al. 2003) and that infected amphibians are detected in the amphibian trade (Mazzoni et al. 2003; Weldon et al. 2004; Garner et al. 2006). The EPH receives support from data showing that Bd was present in global amphibian populations decades ago [USA 1974; Canada 1961; Australia 1978; South Africa 1938 (Rachowicz et al. 2005)] and that there are measurable associations between amphibian condition (Reading 2006), global warming and the onset of chytridiomycosis (Bosch et al. 2006; Pounds et al. 2006)."
Source: www.jcu.edu.au/school/phtm/PHTM/frogs/papers/fisher-2007.pdf
The proposed rule change ignores the Endemic Pathogen Hypothesis (EPH).
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