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Flavobacterium columnare / Myxobolus tilapiae Concurrent Infection in the Earthen Pond Reared Nile Tilapia (Oreochromis niloticus) during the Early Summer
Alaa Eldin Eissa1,*, Manal M. Zaki2 and A. Abdel Aziz3
1Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Cairo University, Giza 11221 Egypt
2Department of Veterinary Hygiene, Faculty of Veterinary Medicine, Cairo University, Giza 11221 Egypt
3Department of Zoology, faculty of Science, Cairo University, Giza 11221 Egypt
*Corresponding author
  Received : May 31, 2010
  Accepted : May 31, 2010
  Published : June 04, 2010
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Synopsis

Flavobacterium columnare (F. columnare), the dermotropic Gram negative yellow pigmented bacteria was isolated from different sites of skin ulcerations in the Nile tilapia (Oreochromis niloticus) and Nile catfish (Clarias gariepinus) collected from an earthen pond located at an aquaculture station in Sharkiya Province, Lower Egypt during an acute episode of mass kills during the early summer of 2009. An acute infection with F. columnare was behind the emergent event of mass mortalities among both populations. Many of the Nile tilapias exhibited typical signs of hole - in- the head like lesions from which F. columnare together with the myxosporean spore, Myxobolus tilapiae (M. tilapiae) were retrieved. Most of the cohabitating infected Nile catfishes exhibited severe form of saddle back like ulcer. The identities of the retrieved isolates were confirmed using morphological, biochemical and molecular tools. The research leads us to conclude that the two diverse etiological agents (F. columnare and M. tilapiae) under the triggering effect of the abrupt change in the water quality measures (abrupt rise in the water temperature, ammonia, pH, sharp decrease in dissolved oxygen) have synergized together to induce the above mentioned pathology with the consequent reemergence of fish mass mortalities.

Keyword: Flavobacterium columnare, Myxobolus tilapiae, mass mortalities, environmental stress, summer, concurrent infection,
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