Combined effects of intestinal parasite infestation and extrinsic stress on the host gross energy in Malapterurus electricus (Teleostei: Malapteruridae) host-parasite system in the Lekki Lagoon, Nigeria

This paper describes combined effects of intestinal parasite infestation and extrinsic stress on the host gross energy in Malapterurus electricus host-parasite system. Eighty (80) fish samples were procured from the Lekki lagoon, Nigeria. Condition factors, organosomatic indices and hepatic glycogen of the individuals were estimated/measured. Infection status and median condition (K 1.4 and K 1.4) of M. electricus were used in grouping the individuals. Histological alterations of the intestines were also observed and scored for Gut-pathological Alteration Index (GAI). Infested individuals harbor Electrotaenia malopteruri (a cestode) and Procamallanus longus (a nematode). Non-infested individuals of low condition factor had the lowest hepatic glycogen; Mean±SD, 6.59±7.02mg/dl, infested individuals; Mean±SD, 18.94±11.18mg/dl, P 0.05, while individuals of high condition factor had higher hepatic glycogen level; infested, Mean±SD, 20.48±34.55mg/dl, non-infested, Mean±SD, 20.69±17.45mg/dl, P 0.01. Individuals of low condition factor had parasite load; E. malopteruri (0.24) and P. longus (0.29), while high condition individuals had; E. malopteruri (0.42) and P. longus (0.47). The infested individuals of high condition factors had the highest mean body weight, gonadosomatic index (GSI), hepatic triglycerides, cholesterone and low density lipids (LDL). Infested individuals of low condition factor had higher gut-pathological alteration index (GAI, 16.0) compared with high condition individuals (GAI, 8.0). These individuals had from mild to severe ulceration of the mucosa and congestion of the blood vessels. They also had one of the highest HSI, Mean±SD, 2.20±1.31, P 0.01 but the lowest GSI, Mean±SD, 4.80±2.9, P 0.01. These individuals depleted almost all their hepatic glycogen and signified reduced reproductive potential but had the highest hepatic energy influx to tissues for cellular metabolism. Parasite infestation and extrinsic stresses have significant impact on host gross energy content. Understanding the physiological mechanism in these stress interactions in the host is highly essential.