External symptoms of infectious hypodermal and hematopoietic necrosis virus (IHHNV) on shrimp. (A,B) subadult Penaeus vannamei with bent (to the left) rostrums, a classic sign of ‘runt deformity syndrome’ (RDS); (C) a juvenile P. vannamei with RDS. In this specimen the rostrum is bent to the right and the antennal flagella are wrinkled, brittle and mostly broken-off; (D) juvenile P. vannamei with RDS from a nursery population at approximately 60 days post stocking (Reprinted from Journal of Invertebrate Pathology, Vol. 106 (1), Lightner D.V., Virus diseases of farmed shrimp in the Western Hemisphere (the Americas) A rieview, p. 21, Copyright (2011), with permission from Elsevier).