Out of 58 live tilapia fish, five Oreochromis niloticus were found to be naturally infected with Henneguya suprabranchiae (8.62%). Such infection was recorded only during winter season from Bahr Shebin, a tributary of the River Nile at Menoufia Governorate, Nile Delta, Egypt. Based on the structure and measurements of fresh spores, this parasite was identified as H. suprabranchiae. Spores are oval in shape and they measure 15 (13-16) x 5 (4-6) microm length by width. It has two polar capsules inside and they measure 4 (5-7) x 1 (2-3) microm length by width. Each polar capsule has spirally coiled (7-9 turns) polar filament. The plasmodia as well as all other parasitic stages were described using light and transmission electron microscopy and discussed regarding to those of other fish hosts especially those of Africa.
Streptococcus iniae cause high mortalities in aquaculture farms all over the world. This study aimed to isolate, identify pathogenicity and genetic relatedness of S. iniae obtained from cultured Nile tilapia (O. niloticus) at Kafr El-Shiekh Governorate. Fourteen isolates of pure S. iniae cultures were biochemically identified, and confirmed through amplification and sequencing of the 16S rRNA gene. Experimental challenge with six selected isolates resulted in marked clinical signs similar to those recorded in natural infections. The LD 50 values were ranged between 3.7×10 7 to 4.3×10 8 cfu/fish. All strains were sensitive to oxytetracycline and florfenicol. In repetitive sequence-based PCR (rep-PCR) analysis using the BoxA primer, isolates presented genetic heterogeneity and were divided into six genotypes banding patterns. Understanding the epizootiology and genetic variability between S. iniae isolates, could help for better control and vaccine development.
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