A comparative analysis of Yellow Head Virus (YHD) diagnostic methods adopted in Sri Lanka to investigate the accuracy and specificity of the virus

Yellow head virus is a common viral pathogen which infects cultured Penaeus monodon world-wide, resulting in immature larvae and the growth retardation. Therefore, several detection methods are recommended by the Office des Epizootics (OIE) for use in Asia including Sri Lanka. This study was attempted to evaluate the RT-PCR diagnostic method is the appropriate and accurate YHV detection method which is recommended by the OIE comparing with histological identification and haemolymph Smear method. A total of 150 individuals of Penaeus monodon, post larve samples obtained from different shrimp hatcheries located in Northwestern province were screened for the presence of YHV and the results were comparatively analyzed with three different protocols, namely wet mount observation, histopathological observation and RT- PCR detection. Highest prevalence was recorded with wet mount observations (78%) and the lowest was recorded using histopathology (22%). Comparison of PCR tests generated consisted of positive samples 31/51 (2010), 38/65(2011) and 18/34 (2012) respectively. The results obtained with the IQ2000 commercial kit, were the most reliable and it indicated 56.6% average prevalence of YHV.