Okavirus is a genus of
viruses in the order
Nidovirales, in the family
Roniviridae. Okaviruses infect
crustaceans, mostly
prawns. There is currently only one species in this genus: the type species Gill-associated virus. Diseases associated with this genus include: GAV: reddening, biofouling with exoparasites, emaciation, massive mortality; YHV: yellow head, arrest of feeding. massive mortality. The name is derived from the 'Oka' or lymphoid organ in which the viruses are commonly detected and in which pathology occurs during acute infections. Lymphoid organs are anatomical structures common to
penaeid shrimp.