Morphological and Molecular Study of Pseudoterranova krabbei Nematoda in Oman Sea Epinephelus Fish

BACKGROUND: As the population grows, there is further need to food, and fish is not an exception. Several fish species are potential sources of common parasites between humans and fish. One of the important diseases common between human and fish is Anisakiasis. The parasitic agent of this disease is the larval stage of the Anisakid family nematodes, including Pseudoterranova and Anisakis.OBJECTIVES: In this study, Epinephelus fish, one of the edible and commercial valuable fishes of the Oman Sea, was examined for the presence of nematodes of the Anizakidae family.METHODS: Fifteen out of the 26 specimens were infected with Nematodes. Nematodes were isolated from fish abdominal area. For morphological study, each nematode sample was first clarified with lactophenol. Subsequently, it was examined using an optical microscope. After morphological examination of these nematodes, DNA extraction was performed. Using primers related to a part of cytochrome oxidase subunit 1 (Cox1), PCR products were 710 bp for PCR reaction. Finally, the amplified fragment was sequenced.RESULTS: The larvae were about 1 to 3 cm long, white, and often twisted. At the anterior end of the parasite, a button was seen, and in some larvae, a terminal spine was observed. In certain larvae, a small abdomen at the end of the esophagus can be seen. Out of the obtained 26 nematode specimens, eight Anisakis specimens were identified following morphological analysis. These specimens had terminal spines and three anterior lips. After sequencing, Pseudoterranova nematode was identified to belong to aniakidae family. Separate clad tree showed paraphylitic for isolated Pseudoterranova.CONCLUSIONS: Morphological examination categorized isolated larvae as the Anizakidae family. Other molecular results of this nematode showed Pseudoterranova krabbei. The results of sequencing this parasite were recorded in the gene bank under the Accession number: MK317965. This nematode was initially isolated from the Oman Sea Epinephelus fish.