Department of Zoology, University of Dhaka, Dhaka, 1000, Bangladesh.
Department of Anthropology, Durham University, South Road, Durham, DH1 3LE, UK.
Ecohealth. 2021 Mar;18(1):31-43. doi: 10.1007/s10393-021-01522-2. Epub 2021 May 24.
Global amphibian populations are facing a novel threat, chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), which is responsible for the severe decline of a number of species across several continents. Chytridiomycosis in Asia is a relatively recent discovery yet there have been no reports on Bd-presence in Bangladeshi amphibians. We conducted a preliminary study on 133 wild frogs from seven sites in Bangladesh between April and July 2018. Nested PCR analysis showed 20 samples (15.04%) and 50% of the tested taxa (9 species from 6 genera and 4 families) as Bd-positive. Eight of the nine species are discovered as newly infected hosts. Analysis of Bd-positive samples shows prevalence does not significantly vary among different land cover categories, although the occurrence is higher in forested areas. The prevalence rate is similar in high and low disturbed areas, but the range of occurrence is statistically higher in low disturbance areas. Maximum entropy distribution modeling indicates high probabilities of Bd occurrence in hilly and forested areas in southeast and central-north Bangladesh. The Bd-specific ITS1-5.8S-ITS2 ribosomal gene sequence from the Bd-positive samples tested is completely identical. A neighbor-joining phylogenetic tree reveals that the identified strain shares a common ancestry with strains previously discovered in different Asian regions. Our results provide the first evidence of Bd-presence in Bangladeshi amphibians, inferring that diversity is at risk. The effects of environmental and climatic factors along with quantitative PCR analysis are required to determine the infection intensity and susceptibility of amphibians in the country.
全球两栖动物种群正面临一种新的威胁，即蛙壶菌病（Batrachochytrium dendrobatidis，Bd）引起的疾病，这种疾病导致了多个大陆的许多物种严重减少。亚洲的蛙壶菌病是最近才发现的，但尚未有关于孟加拉国两栖动物存在 Bd 的报告。我们于 2018 年 4 月至 7 月期间对来自孟加拉国七个地点的 133 只野生青蛙进行了初步研究。巢式 PCR 分析显示 20 个样本（15.04%）和 50%的测试分类群（6 属 4 科的 9 种）为 Bd 阳性。在这 9 种中，有 8 种是新发现的感染宿主。对 Bd 阳性样本的分析表明，不同的土地覆盖类别之间的流行率没有显著差异，尽管森林地区的发病率较高。高干扰和低干扰地区的流行率相似，但低干扰地区的发病范围统计学上更高。最大熵分布模型表明，Bd 在孟加拉东南部和中北部丘陵和森林地区出现的概率较高。从 Bd 阳性样本中测试的 Bd 特异性 ITS1-5.8S-ITS2 核糖体基因序列完全相同。基于 ITS1-5.8S-ITS2 核糖体基因序列的邻接聚类分析树表明，所鉴定的菌株与以前在不同亚洲地区发现的菌株具有共同的祖先。我们的研究结果首次提供了孟加拉国两栖动物存在 Bd 的证据，推断多样性正面临威胁。需要结合环境和气候因素以及定量 PCR 分析来确定该国两栖动物的感染强度和易感性。
