Marcer Federica, Cassini Rudi, Parisotto Nancy, Tessarin Cinzia, Marchiori Erica
Department of Animal Medicine, Production and Health, University of Padova, Legnaro, Italy.
Front Vet Sci. 2022 Jun 27;9:908486. doi: 10.3389/fvets.2022.908486. eCollection 2022.
Free-ranging cetaceans are considered sentinels for the marine ecosystem's health. New and non-invasive methods have been set up for the collection of fecal samples from free-ranging big whales at sea, permitting to gain an excellent epidemiological picture of parasitic infections in wild populations. To select the best protocol to be used for copromicroscopic examination in cetaceans stool samples, we evaluated the sensitivity of two commonly used techniques, i.e., a sedimentation-floatation method and the Mini-FLOTAC through validation by helminth isolation from the digestive tract. For this aim, gastrointestinal content and fecal samples were collected during necropsy from 44 cetaceans, including bottlenose dolphins (), striped dolphins (), sperm whales (), Risso's dolphins (), Cuvier's beaked whales (), pilot whale (), and fin whales (). Helminths were recovered through washing and filtering of the gastrointestinal contents and morphologically identified. Copromicroscopic examinations were performed on formalin-preserved fecal samples, using a sodium nitrate, sodium thiosulphate, and sucrose solution (s.g. = 1.450) for both methods. Helminths belonging to 9 taxa (i.e., the trematodes , the nematode sp., cestodes of the family Tetrabothriidae and the acanthocephalan sp.) were isolated. Eggs referable to the same taxa, with the exception of cestodes, were found in copromicroscopic analyses. Sensitivity of the Mini-FLOTAC method appeared higher or equal for all taxa, proving superior to the sedimentation-flotation method for the detection of all except sp. The concordance of the two tests indeed revealed a moderate to perfect agreement ( values 0.42-1). Not excluding the limitations inherent to the techniques themselves, explanations for false-negative results at copromicroscopy could be linked to parasite-related factors, including prepatent infections, low parasitic burdens, or intermittent egg shedding. Notwithstanding these limitations, this study evidenced that the Mini-FLOTAC protocol approximates more accurately the composition of the gastrointestinal helminthic community of cetaceans from copromicroscopic examination, providing at the same time a quantitative estimation.
自由放养的鲸类动物被视为海洋生态系统健康状况的哨兵。现已建立了新的非侵入性方法，用于在海上从自由放养的大型鲸鱼身上采集粪便样本，从而得以全面了解野生种群中寄生虫感染的流行病学情况。为了选择用于鲸类粪便样本粪便显微镜检查的最佳方案，我们通过从消化道分离蠕虫进行验证，评估了两种常用技术的敏感性，即沉淀浮选法和Mini-FLOTAC法。为此，在尸检期间从44头鲸类动物身上采集了胃肠道内容物和粪便样本，其中包括宽吻海豚、条纹海豚、抹香鲸、里氏海豚、柯氏喙鲸、领航鲸和长须鲸。通过冲洗和过滤胃肠道内容物回收蠕虫，并进行形态学鉴定。使用硝酸钠、硫代硫酸钠和蔗糖溶液（比重=1.450）对福尔马林固定的粪便样本进行两种方法的粪便显微镜检查。分离出了属于9个分类群的蠕虫（即吸虫、线虫属、四叶目绦虫和棘头虫属）。在粪便显微镜分析中发现了除绦虫外可归为相同分类群的虫卵。Mini-FLOTAC方法对所有分类群的敏感性似乎更高或相同，事实证明，除属外，该方法在检测所有其他分类群时均优于沉淀浮选法。两种检测方法的一致性确实显示出中度至完全一致（值为0.42-1）。尽管不排除技术本身固有的局限性，但粪便显微镜检查出现假阴性结果的原因可能与寄生虫相关因素有关，包括潜伏期感染、低寄生虫负荷或间歇性排虫卵。尽管存在这些局限性，但本研究证明，Mini-FLOTAC方案通过粪便显微镜检查能更准确地近似鲸类动物胃肠道蠕虫群落的组成，同时提供定量估计。
