Huffmanela spp. (Nematoda: Trichosomoididae) from Orange-spotted Grouper (Epinephelus coioides, Hamilton, 1822) at Jubail Province, on the Arabian Gulf, Saudi Arabia: A case report

This paper is conducted for identifying the parasite which collected during regular routine inspection for the hygienic condition and health status of fish in 2019 at the central fish market shops at Jubail city, Saudi Arabia. Samples from an orange spotted grouper (Epinephelus coioides) fish showed heavy black streaks between the muscle fibers that was considered unmarketable and rejected by the consumer after had been cut and prepared for sealing. The black discolorations were in the form of heavy diffused focal black spots or forming threads of variable sizes embedded in the entire whole-body musculature of the fish. These samples were subjected to parasitological and pathological evaluation. The parasitological examination of the affected muscular tissues revealed Huffmanela spp. eggs infection. The parasitic infestation was identified on the bases of the morphological and ultra-structural characters of the eggs. The histopatholgical investigation of the dark discoloration of the muscular tissues showed severe diffused multifocal granulomatous myositis reactions in the form of chronic inflammatory response accompanied with fibrous connective tissue proliferation around the eggs and larvae together with lymphocytes and macrophages aggregation. Muscular necrosis, edema and evidence of muscular regeneration were also noticed. In conclusion; this case report confirmed the occurrence of Huffmanela spp. infection in the muscles of Epinephelus coioides by using light and scanning electron microscopy.Further molecular assessment is recommended.