Histopathology effects of <i>Myxobolus pethericii</i> Fomena, Lekeufack Folefack and Tang II, 2007 on <i>Ctenopoma petherici</i> Günther, 1864, in the Sangé River, Littoral Region, Cameroon

Abstract

Histological method, becoming common in diagnostic methodology, provides information on effect of parasite and help predicting therapeutic measures for aquatic animals. Ctenopoma petherici caught in Sangé River were examined for myxozoan infections. Cyst measurements were taken and prevalence was estimated. Formalin-fixed organs were dehydrated through a graded ethanol series and embedded in paraffin. Obtained sections were stained with hematoxylin and eosin. From examined fish, 93.33% harbored elongated, ovoid or spherical cysts measuring 70 - 660 µm long × 40 - 390 µm wide in one or more of the following organs: gills, heart, stomach, liver, gonads, eyes, skin, bones, muscles, intestine, mesentery, fins, opercula, esophagus, labyrinth organs, kidney, swimbladder, and gallbladder. Cysts were arranged anarchically on affected organs and their development was asynchronous. Histological observations revealed cysts implantation mostly in loose connective tissue on which they induce one or more of the following: hyperplasia, swelling, alteration and lack of adhesion between tissue layers. In some cases, cysts were responsible of mechanical compression and distortion of blood vessels surrounding affected tissue. In many cases, significant portion of affected organs was replaced by numerous and voluminous cysts leading to tissue destruction and reduction of organ’s functional area. Generally, few sign of fish immune response to the presence of cysts was observed. Histological examination of Ctenopoma petherici appears as an important tool for rapid diagnosis to ensure farming production. Therefore, monitoring M. pethericii in farmed fish using histological method would help in early and proper drug therapy and avoid it dissemination.