Environmental Futures Research Institute, School of Environment, Griffith University, Gold Coast Campus, Queensland, Australia.
Environmental Futures Research Institute, School of Environment, Griffith University, Nathan Campus, Queensland, Australia.
PLoS One. 2014 Mar 19;9(3):e92499. doi: 10.1371/journal.pone.0092499. eCollection 2014.
Batrachochytrium dendrobatidis (Bd), a cutaneous amphibian fungus that causes the lethal disease chytridiomycosis, has been implicated as a cause of many amphibian declines. Bd can tolerate low temperatures with an optimum thermal range from 17-24°C. It has been shown that Bd infection may result in species extinction, avoiding the transmission threshold presented by density dependent transmission theory. Prevalence of Bd during autumn and winter has been shown to be as low as 0% in some species. It is currently unclear how Bd persists in field conditions and what processes result in carry-over between seasons. It has been hypothesised that overwintering tadpoles may host Bd between breeding seasons. The Great Barred Frog (Mixophyes fasciolatus) is a common, stable and widespread species in Queensland, Australia, and is known to carry Bd. Investigation into Bd infection of different life stages of M. fasciolatus during seasonally low prevalence may potentially reveal persistence and carry-over methods between seasons. Metamorphs, juveniles, and adults were swabbed for Bd infection over three months (between March and May, 2011) at 5 sites of varying altitude (66 m-790 m). A total of 93 swabs were analysed using Polymerase Chain Reaction (PCR) real-time analysis. PCR analysis showed 6 positive (1 excluded), 4 equivocal and 83 negative results for infection with Bd. Equivocal results were assumed to be negative using the precautionary principle. The 5 positive results consisted of 4 emerging (Gosner stage 43-45) metamorphs and 1 adult M. fasciolatus. Fisher's exact test on prevalence showed that the prevalence was significantly different between life stages. All positive results were sampled at high altitudes (790 m); however prevalence was not significantly different between altitudes. Infection of emerging metamorphs suggests that individuals were infected as tadpoles. We hypothesise that M. fasciolatus tadpoles carry Bd through seasons. Thus, Mixophyes fasciolatus may act as disease reservoirs at multiple life stages.
蛙壶菌（Batrachochytrium dendrobatidis，Bd）是一种导致致命疾病壶菌病的皮肤两栖真菌，被认为是许多两栖动物减少的原因。Bd 可以耐受低温，最适温度范围为 17-24°C。已经表明，Bd 感染可能导致物种灭绝，避免了密度依赖传播理论提出的传播阈值。在一些物种中，秋季和冬季的 Bd 流行率低至 0%。目前尚不清楚 Bd 如何在野外条件下持续存在，以及哪些过程导致了季节之间的传播。有人假设，越冬蝌蚪可能在繁殖季节之间携带 Bd。大斑蟾（Mixophyes fasciolatus）是澳大利亚昆士兰州常见、稳定和广泛分布的物种，已知携带 Bd。在季节性低流行率下调查 M. fasciolatus 不同生命阶段的 Bd 感染情况，可能会揭示季节之间的持久性和传播方法。在三个月（2011 年 3 月至 5 月）内，在 5 个不同海拔（66 米-790 米）的地点，对变态期、幼体和成体进行了 Bd 感染的拭子检测。使用聚合酶链反应（PCR）实时分析对总共 93 个拭子进行了分析。PCR 分析显示，有 6 个阳性（1 个排除）、4 个不确定和 83 个阴性结果感染了 Bd。根据谨慎原则，不确定结果被假定为阴性。5 个阳性结果包括 4 个正在发育的（戈斯纳阶段 43-45）变态期和 1 个成年 M. fasciolatus。对流行率进行 Fisher 精确检验表明，不同生命阶段的流行率存在显著差异。所有阳性结果均在高海拔（790 米）处采样；然而，海拔之间的流行率没有显著差异。正在发育的变态期个体的感染表明，个体在蝌蚪阶段就感染了 Bd。我们假设 M. fasciolatus 蝌蚪通过季节携带 Bd。因此，Mixophyes fasciolatus 可能在多个生命阶段充当疾病储主。
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