Trichodiniasis is one of the most serious ectoparasitic diseases disturbing tilapia aquaculture worldwide, causing deleterious effects and significant economic losses. This study aimed to characterize two Trichodina species concomitantly infecting farmed Nile tilapia Oreochromis niloticus based on integrated morphological, molecular, and immunological approaches. One hundred and eighty of 250 examined Nile tilapia were found to be infected with trichodinids belonging to the family Trichodinidae, with an overall prevalence rate of 72%. The morphological characterization of trichodinids fixed on Giemsa-stained smears revealed that fish were concomitantly infected with Trichodina heterodentata and T. centrostrigeata. Subsequently, the phylogenetic analysis of the 18S rRNA gene of the two investigated trichodinids confirmed the detected species’ identities. The gene expression levels of MHCIIβ and CD4 gens were increased during the trichodinid infection. Furthermore, potassium permanganate and hydrogen peroxide chemicals, which have well-known records for treating ectoparasites infections in farmed fish, were successfully verified to control trichodiniasis in a small-scale trial.

中文翻译：

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两种毛虫共感染（纤毛虫：毛虫科）的形态分子鉴定及其对养殖尼罗罗非鱼的免疫学影响

滴虫病是世界范围内扰乱罗非鱼养殖业的最严重的外寄生虫病之一，造成有害影响和重大经济损失。本研究旨在基于综合形态学、分子学和免疫学方法表征同时感染养殖的尼罗罗非鱼Oreochromis niloticus的两种毛滴虫。经检查的 250 条尼罗罗非鱼中有 180 条感染了属于Trichodinidae科的Trichodinids，总体流行率为 72%。固定在吉姆萨染色涂片上的木霉的形态特征表明，鱼同时感染了异齿木霉和T。中心纹亚目。随后，对两个被研究的毛虫的 18S rRNA 基因的系统发育分析证实了被检测物种的身份。MHCIIβ 和 CD4 基因的基因表达水平在毛虫感染期间增加。此外，高锰酸钾和过氧化氢化学品在治疗养殖鱼类体外寄生虫感染方面有着众所周知的记录，在小规模试验中成功地控制了滴虫病。