RT-nested PCR as described in Cowley et al. (2005) (Diseases of Aquatic Organisms, 66, 91–104) or real-time PCR as described in Rajendran et al. (2006) (Journal of Virological Methods, 137, 265–271) on RNA extracted from lymphoid organ, hemocytes gill tissue of juvenile or adult shrimp, on whole post-larvae.