Uma Arumugam, Subash Palaniappan, Praveenraj Jayasimhan
Department of Aquatic Animal Health Management, Dr. M.G.R. Fisheries College and Research Institute, Tamil Nadu Dr. J. Jayalalithaa Fisheries University, Ponneri, Tamil Nadu, 601204, India.
State Referral Laboratory for Aquatic Animal Health, Tamil Nadu Dr. J. Jayalalithaa Fisheries University, Madhavaram Campus, Madhavaram milk colony, Chennai, Tamil Nadu, 600 051, India.
Acta Parasitol. 2025 Jan 7;70(1):13. doi: 10.1007/s11686-024-00961-5.
Henneguya sp. is a crucial myxosporean parasite known to cause milky flesh or tapioca disease in the freshwater fish population, leading to heavy mortality. Studies to investigate its host range and to monitor their prevalence in wild and aquacultured fish are necessary.
The infected orange-spotted snakehead (Channa aurantimaculata) fish samples showing clinical signs such as severe ulceration and open wounds on the mouth and operculum were collected from an ornamental fish-rearing unit in Chennai, Tamil Nadu. The sample was diagnosed with myxosporean infection by microscopic observation, morphological records and DNA sequencing followed by phylogenetic analysis.
The Henneguya infection was identified in C. aurantimaculata for the first time. Necropsy of the infected fish revealed characteristic multifocal whitish-yellow, oval-shaped cysts measuring 3-5 mm in length on the liver and spleen. The wet mount of cysts showed numerous mature Henneguya spores that were uninucleate, elongated, lenticular and ellipsoidal with the bluntly rounded anterior end gradually tapering off to the posterior with a caudal elongation. The spore body measured 12.1 ± 0.9 μm (10.1-14.7 μm) × 7.1 ± 0.6 μm (5.3-8.5 μm) with two slightly unequal pyriform polar capsules of 6.1 ± 0.5 μm (5.1-7.4 )× 2.5 ± 0.4 μm (1.6-3.9) (large); 6.0 ± 0.4 μm (5.2-6.4) × 2.5 ± 0.3 μm (1.7-3.1) (small) and a caudal elongation of 16.1 ± 1.2 μm in length. The parasite was confirmed to be a Henneguya sp. by PCR amplification of SSrRNA followed by gene sequencing. The sequence generated was submitted in the GenBank under accession number PP852214.1 The maximum likelihood analysis revealed that the obtained sequence is a close relative of H. exilis with pairwise sequence variation of 3.3% and a homology of 99.04%.
The findings highlight the potential impact of Henneguya sp. on ornamental fish health, underscoring the need for vigilant monitoring and management in India.
亨内古亚属（Henneguya sp.）是一种重要的黏孢子虫寄生虫，已知会在淡水鱼种群中引发乳白肉病或木薯病，导致大量死亡。开展研究以调查其宿主范围并监测其在野生和养殖鱼类中的流行情况很有必要。
从泰米尔纳德邦金奈的一个观赏鱼养殖单位收集了感染的橙斑鳢（Channa aurantimaculata）鱼样本，这些样本表现出严重溃疡以及嘴部和鳃盖有开放性伤口等临床症状。通过显微镜观察、形态学记录和DNA测序，随后进行系统发育分析，对样本进行了黏孢子虫感染诊断。
首次在橙斑鳢中鉴定出亨内古亚属感染。对感染鱼进行尸检发现，肝脏和脾脏上有特征性的多灶性黄白色椭圆形囊肿，长3 - 5毫米。囊肿的湿片显示有许多成熟的亨内古亚属孢子，这些孢子单核，呈细长形、双凸透镜状和椭圆形，前端钝圆，向后逐渐变细，有尾突延长。孢子体大小为12.1±0.9微米（10.1 - 14.7微米）×7.1±0.6微米（5.3 - 8.5微米），有两个略不等的梨形极囊，大的极囊大小为6.1±0.5微米（5.1 - 7.4微米）×2.5±0.4微米（1.6 - 3.9微米）；小的极囊大小为6.0±0.4微米（5.2 - 6.4微米）×2.5±0.3微米（1.7 - 3.1微米），尾突延长长度为16.1±1.2微米。通过对SSrRNA进行PCR扩增并测序，确认该寄生虫为亨内古亚属。所产生的序列已提交至GenBank，登录号为PP852214.1。最大似然分析显示，获得的序列是微小亨内古亚（H. exilis）的近亲，序列差异为3.3%，同源性为99.04%。
这些发现凸显了亨内古亚属对观赏鱼健康的潜在影响，强调了印度进行警惕监测和管理的必要性。
