yellow head disease

International Common Names

• English: yellow head shrimp disease; yellow head virus disease; yellowhead disease; yellowhead disease of penaeid shrimp; yellow-head shrimp disease; yellow-head virus disease; yellow-head virus disease (YHD) of penaeid shrimp

English acronym

• YHD

Yellow head disease, caused by Yellow head virus (genotype 1) (YHV1), has resulted in significant mortalities of penaeid shrimp in Asia (Flegel, 2012). The disease was first described in Penaeus monodon in Thailand in 1990 by Limsuwan (Chantanachookin et al., 1993). The syndrome was given its name due to the light yellow colouration of the dorsal cephalothorax area and the general pale appearance of the infected prawn. This yellow appearance was a result of the underlying enlarged yellow hepatopancreas.

YHV1 is one of six known genotypes in the yellow head complex of viruses. Gill-associated virus (GAV) is designated as genotype 2. GAV and four other known genotypes in the complex (genotypes 3–6) occur commonly in healthy Penaeus monodon in East Africa, Asia and Australia and are rarely or never associated with disease (Wijegoonawardane et al., 2008). YHV and other genotypes in the yellow head complex are classified as a single species (Gill-associated virus) in the genus Okavirus, family Roniviridae, order Nidovirales. There is evidence of genetic recombination between genotypes (Wijegoonawardane et al., 2009).

‘Infection with yellow head virus’ is on the list of diseases notifiable to the World Organisation for Animal Health (OIE). For further information on this disease from OIE, see the website: www.oie.int