YERSINIA MICROORGANISMS AS THE CAUSATIVE AGENT OF ENTERIC RED MOUTH DISEASE IN DELTA NILE FISHES

Abstract

Trials were carried out to examine large numbers of different kinds of Nile Delta water fishes including: 0.niloticus; C. lazera; Ch. auratus and C. carpio in order to obtain a vivid picture of "Yersiniosis" in Egypt.

• Out of 440 apparently normal and diseased fishes, 49 cases revealed the presence of Y. ruckeri with an overall incidence of(ll.l %). Thus, "Yersiniosis" has been considered prevalent in both apparently normal and diseased fishes in Egypt.

• The prevalence rate of Y.ruckeri in apparently normal 0. niloticus;

C. /azera; C. carpio and Ch. auratus were (12.5 %, 8.0%, 5.0% )and

10.0%) respectively. The relation between environmental stress factors and asymptomless carrier: fishes is described in details.

• Out of diseased 0. niloticus examined, II fish harboured Y. ruckeri (13.8%) and out of 125 diseased C. /azera examined, 14 cases proved to be infected with the organism (11.2%).

• The signs of "Yersiniosis" are erosion of jaws with congestion of hard palates, haemorrhages occurs• on the • body surfaces, at the gill tips, at the base• of the fins and around the lateral line: No ulCers ' ' . were noticed.. The .. 'vent•'•. ' area • . became.•••inflamed • externally . and

internally. Darkening of the skin was sometimes noticed. Bilateral exophthalmia• luis ben occurred iii chrorii'cases.