Haemato-histopathological effect of experimental infection of Aeromonas hydrophila isolates on Oreochromis niloticus

Abstract

Motile Aeromonas Septicemia caused by Aeromonas hydrophila is an important bacterial disease of Nile tilapia (Oreochromis niloticus). This study aimed to evaluate the effects of infection on the blood parameters and on architectural integrity of tissues of the fish. Experimental A. hydrophila infection of O. niloticus juveniles was carried out using isolates from infected fish in the Kainji lake area. Following intraperitoneal injection, the effects of the bacteria on gross, hematological and histological integrity of the fish were analyzed. The bacterial isolate induced mortality and morbidity in the fish. There were significantly (p<0.05) lower red blood cell and higher total white blood cell counts in experimentally infected fish than in the control. Lesions observed following A. hydrophila infection included dilation of the sinusoids and vacuolation of hepatocytes of the liver, and interstitial necrosis with infiltration of lymphocytes and macrophages in the kidneys. Macrophage hyperplasia and lymphoid depletion in the spleen, fusion of adjacent secondary lamellae, epithelial necrosis and desquamation in the gills were recorded in the infected fish, too. The study demonstrates that A. hydrophila induces both hematological and histopathological alterations in the tissues of infected O. niloticus.

Keywords

• aeromonas hydrophila
• oreochromis niloticus
• haematology
• histopathology
• kainji lake