PREVALENCE OF Vibrio sp. IN CULTURED WHITELEG SHRIMP (Litopenaeus vannamei) ASSOCIATED WITH CLINICAL SIGN OF ACUTE HEPATOPANCREATIC NECROSIS DISEASE (AHPND)  

Iftikhar Ahmad A. R.*, Kua B. C., Kamisa A., Nur Ashikin A. & Nuruljannah H.
 
National Fish Health Research Division,
Fisheries Research Institute Batu Maung,
Department of Fisheries Malaysia,
11960, Bayan Lepas, P. Pinang, Malaysia
iftikhar@dof.gov.my

Acute Hepatopancreatic Necrosis Disease (AHPND) is a bacterial disease caused by Vibrio parahaemolyticus and has caused high mortality in farmed Whiteleg shrimp. It appears within 30 days of stocking and causes symptoms such as lethargy, empty stomach and midgut, pale and atrophied hepatopancreas, darkened shells and mottling of the carapace. This study was conducted to relate the prevalence of Vibrio sp. in cultured Whiteleg shrimp associated with AHPND's clinical signs.

An epidemiological study of AHPND was conducted in one Whiteleg shrimp's (Litopenaeus vannamei) culture facility in Perak, Malaysia from April until June 2016. Sampling of shrimps were done on periodically basis on day of culture (DOC) 28, 62 and 85 involving gross observation, bacteriology and Polymerase Chain Reaction (PCR) analysis of each shrimp's hepatopancreas sample.

Results showed that 8.89% of 90 shrimps examined had clinical signs of AHPND. Analysis of PCR using AHPND AP4 kit showed all samples were negative. However, the presence of bacterium V. parahaemolyticus was high (90%) at DOC85, 60% and 37% at DOC62 and 28; respectively. Apart from V. parahaemolyticus, other bacteria found were V. fluvialis, V. alginolyticus and V. vulnificus. Prevalence of V. fluvialis at DOC28, 62 and 85 were 13, 27 and 60%; respectively while for V. alginolyticus ranging from 30 to 43%. V. vulnificus was found at DOC62 and 85 with prevalence of 33 and 10%; respectively.

This study showed that the presence of V. parahaemolyticus will not always coincide with the presence of bacterial toxin plasmid although the clinical signs of AHPND were visible in sampled shrimps.