The main aim of this study was to investigat
e the clinical and postmortem finding, seasonal
prevalence. And histopthological altertions that
are caused by probably a new species of
Myxobolus in ovaries of sharptooth catfish , Clarias gariepinus. In Assiut , Egypt Out of 120 fish
examined over one year (2004) , ovaries of only
15 (12. 5%) fish were infested with macroscopic
Myxobolus cysts (plasmodia and host cyst) that
were embedded in the connective tissue among ova.
Prevalence of infestation started low in late
autumn and increased over winter and reached
maximum in early spring . Infestation was not reco
rded in summer. Six (40%) out of the infested
fish had Myxoblus cysts in only one ovary , meanwhile, the reminder (60%) of infested fish had
both ovaries infested . Also , intensity of in
festation gradually increa
sed over winter and was
maximal in early spring . but abruptly declined
in summer. Microscopic examination of plasmodia
showed numerous typical Myxobolus spores at var
ious developmental stages. Mature spores are
oval in shape with two anteriorly located polar capsules that have 4-5 coils of polar filaments .
Microscopic examination of infested ovaries reveale
d that Myxobolus plasmodia were encapsulated
within a thin connective tissue layer of host react
ion. Myxoblous cysts compress neighboring tissues
causing atrophy of ova and local circulatory dist
urbances . Based on the tissue location of
plasmodia and morphological character of the ma
ture spores, the parasite in the present study
might be a new species. |
