Eissa I.A.M*, A. S. Diab**,

S.F.M. Saker** and A.A. Ahmed**

*Fish Disease and Management Dept., Faculty of Veterinary Medicine, Suez Canal University, Egypt

**Central laboratory for Aquaculture Researches (El-Abbassa), Agriculture Research center, Egypt.

Received 6/ 10/ 2013

Accepted 22/ 11/ 2013


A total number of 500 juvenile specimens of M. rosenbergii were collected during (2011) from Alexandria (Maruit). These specimens were transferred to the laboratory of Central Laboratory for Aquaculture Research (CLAR), Abbassa, Sharkia, Egypt. Some specimens were characterized by reduction in activity, locomotion and progressive weakening of their swimming ability. Prawn stayed at edge of the pond and swam slowly at the water surface then finally sinking to the bottom. Other specimens seemed to have white muscles by naked eye covering the carapace, abdominal region and tail. Some specimens were preserved in devidson’s preservative for histopathological examination. Each five specimens were pooled for extraction of RNA and carrying out of nested RTPCR analysiss for diagnosis of white tail disease caused by Macrobrachium rosenbergii nodavirus (MrNV), and extra small virus (XSV). Clinical examination revealed that white coloration of all prawn body (tail, abdominal muscle and carapace) with degeneration of telson and uropods. Another prawn specimens show whitish coloration of abdominal muscle with normal cephalothorax and tail region. Histopathological examination showed Zenker’s necrosis, hyaline degeneration and accumulation of edematous fluids leading to irregular fissuring and open spaces in striated muscle of the cephalothorax, abdomen and tail. While, Hepatopancreas showed basophilic intracytoplasmic inclusion bodies. Percentage of MrNV infections by nested RTPCR were 40% of prawn with clinical signs and 3.53% of prawn without clinical signs. While Percentage of infections by nested RTPCR were 33.3% of prawn with clinical signs of XSV and 2.3% of prawn without clinical signs. The percentage of specimens infected with MrNV and XSV virus together were 77.8% by nested RTPCR. However, the percentage of specimens infected with MrNV virus alone without XSV were 22.2% by using nested RTPCR.