Haematological changes in Nile tilapia experimentally infected with Enterococcus sp

Area of Science:

• Aquatic animal health
• Fish immunology
• Bacteriology

Background:

• Enterococcus species are opportunistic pathogens affecting various fish species.
• Understanding the haematological response to Enterococcus infection is crucial for aquaculture health management.
• Nile tilapia (Oreochromis niloticus) are economically important food fish susceptible to bacterial diseases.

Purpose of the Study:

• To evaluate the haematological alterations in Nile tilapia experimentally infected with Enterococcus sp.
• To determine the dose-dependent effects of Enterococcus infection on fish blood parameters.
• To assess the immune response of Nile tilapia to bacterial challenge.

Main Methods:

• Experimental infection of Nile tilapia with two different doses of Enterococcus sp. (1 x 10^3 and 1 x 10^6 CFU/mL).
• Control groups included non-injected fish and fish injected with sterile saline.
• Haematological analysis including red blood cell count, white blood cell count, hematocrit, thrombocyte count, and differential white blood cell count.

Main Results:

• Fish infected with 1 x 10^6 CFU/mL Enterococcus showed significantly higher thrombocyte counts.
• White blood cell and lymphocyte counts increased significantly in fish infected with the higher bacterial dose.
• Hematocrit levels were elevated in fish exposed to both 1 x 10^3 and 1 x 10^6 CFU/mL Enterococcus.

Conclusions:

• Enterococcus infection induces notable haematological changes in Nile tilapia, indicative of an immune response.
• The severity of haematological alterations is dose-dependent, with higher bacterial loads eliciting a stronger response.
• These findings contribute to understanding fish disease pathogenesis and developing strategies for disease control in aquaculture.