Department of Biosciences, College of Science, Swansea University, Swansea SA2 8PP, Wales, UK.
Department of Biosciences, College of Science, Swansea University, Swansea SA2 8PP, Wales, UK.
J Invertebr Pathol. 2020 Mar;171:107338. doi: 10.1016/j.jip.2020.107338. Epub 2020 Feb 6.
Sacculina carcini is a common parasite of the European shore crab, Carcinus maenas. Following successful penetration of the host, numerous rootlets are formed that permeate through the hosts' tissues. Ultimately, these form an externa that houses the developing nauplii larvae of the parasite. Most studies have quantified levels of infection by counting the presence of reproductive externae and their breakdown structures, called scars. However, the diagnosis of the disease based only on external features may lead to underreporting the prevalence of the parasite. In the current study, we examined the presence and severity of S. carcini in C. maenas (n = 221) in the Prince of Wales Dock, South Wales, U.K. using a range of diagnostic approaches to give an accurate representation of temporal dynamics of infection. Parasitized crabs were found with a mean prevalence of 24% as determined by histological examination of the hepatopancreas. However, the prevalence of S. carcini based on the presence of externae and scars was only 6.3% and 1.8%, respectively. Overall, parasitism was associated with smaller crabs, crabs later in the moulting cycle that were orange in colour (as opposed to green or yellow), and those with a higher number of bacteria in the haemolymph. Interestingly, only 7.5% of infected crabs showed evidence of distinct host (cellular) response to the presence of rootlets in the hepatopancreas.
藤壶是欧洲滨蟹（Carcinus maenas）的一种常见寄生虫。在成功穿透宿主后，会形成许多根状突起，穿透宿主组织。最终，这些根状突起形成一个外部结构，容纳寄生虫的幼体桡足幼虫。大多数研究通过计数生殖外囊及其分解结构（称为疤痕）的存在来量化感染水平。然而，仅基于外部特征诊断疾病可能导致寄生虫的流行率被低估。在本研究中，我们使用一系列诊断方法检查了英国南威尔士王子码头的欧洲滨蟹（n=221）中藤壶的存在和严重程度，以准确反映感染的时间动态。通过对肝胰腺的组织学检查，发现寄生蟹的平均患病率为 24%。然而，根据外囊和疤痕的存在来确定藤壶的患病率仅为 6.3%和 1.8%。总体而言，寄生虫感染与体型较小的螃蟹、处于蜕皮周期后期的螃蟹（呈橙色而非绿色或黄色）以及血淋巴中细菌数量较多的螃蟹有关。有趣的是，只有 7.5%的受感染螃蟹显示出对肝胰腺中根状突起存在的明显宿主（细胞）反应的证据。
