We already have a very sensitive test for Bsal which is a major step towards being able to effectively deal with this problem. The diagnostic test protocol is to swab individual salamanders and then use TaqMan qPCR with primers designed to detect Bsal. [vc_row][vc_column width=”2/3″][text_output]This method is published and uses the same qPCR technique used to detect Bd, except with Bsal primers instead of Bd primers. The technique is very sensitive for Bd and Bsal detection (down to 0.1 zoospore genome equivalents). TaqMan qPCR is the most sensitive method to detect Bd (as opposed to histology and immunology methods) (Hyatt et al. 2007).
Effective treatments are still being developed and tested however a recent paper by Blooi et al. demonstrated that heat treatment might be an option for some species.
The question has arisen: would clean trade measures need to apply “order-wide” or only to some high-risk imported species? The answer is complicated by the limited testing of salamander susceptibility to Bsal that has occurred to date.
Imagine this scenario: ten airliners arrive in the U.S. on the same day from the same country that is experiencing an outbreak of a lethal and highly contagious disease such as Ebola. Minimal testing is conducted of passengers on five of the planes and Ebola is found on four of those five planes. Would a Federal health official be comfortable allowing all the passengers on all ten planes to enter without further measures to ensure they did not have Ebola, even from the untested planes?
Of course the answer would be no, therefore we felt the situation should be no different for salamanders. Working with scientists, we identified two key reasons why we felt order-wide emergency regulations are necessary:
Evolutionary reasons: A member of the family Sirenidae, Siren, and a member of the family Hynobiidae, Salamandrealla, were found to be a carrier of Bsal. These are ancient families strongly suggesting that the ability to carry Bsal is an early-evolved, primitive trait, and therefore that it will occur in all species in all salamander families unless it is shown not to.
Statistical reasons: There are ten families of salamanders of which five have been minimally tested for ability to be infected. Four of the five families had members that can be infected (carriers).
Importantly, a positive result with minimal sampling does prove members of the family can be infected, while a negative result with minimal sampling does not provide strong evidence that the family cannot be infected. In laboratory testing, only one family (the Ambystomatidae) out of five was found to be “not infectible”. However, it is important to note that this result is based on minimal sampling: ten individuals of two species in this family. With such a small sample size it is impossible to make a definitive conclusion about whether members of this family can carry infection, and it would be inaccurate to generalize this to all species in this family. Therefore, the best evidence is that species in four of four families can be infected, and we are not sure about the other six families because testing has not been completed or has not begun.
The statistical argument for order-level regulation is that we are sure that species in four tested families can be infected and act as carriers, including a species in an ancient lineage (Sirenidae). Thus, it is highly probably that the other six families for which testing is not complete will include species that can be infected and act as carriers.
At this point, we want to stress that all evidence currently available suggests that Bsal has not yet arrived in the U.S. and so our primary focus is to push forward policy actions and work with importers to keep it out. However, we just don’t know how effective existing voluntary measures are in keeping diseases from invading wild populations when amphibians are imported.
By James P. Lewis, Reid Harris, Candace M. Hansen-Hendrikx & Peter Jenkins
[/text_output][text_output]In part three of this blog series we will take a look at the roles the pet industry and pet keepers alike can play in keeping both captive and wild salamanders safe from emerging amphibian diseases, the development of an international disease-monitoring portal and how we move forward as a community from here.
Read Part 1 of this series here and Part 3 of this series here.[/text_output][/vc_column][vc_column width=”1/3″][text_output]Photo: Slimy salamander (Plethodon glutinosus) © Jason Ross[/text_output][text_output]References:
A. Martel et al., Science 346, 630–631 (2014). DOI: 10.1126/science.1258268
A. D. Hyatt et al., Dis. Aquat. Organ. 73, 175–192 (2007).
M. Blooi et al., Sci. Rep. 5, 1 (2015) DOI: 10.1038/srep08037
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