Yellowhead disease (YHD) of penaeid shrimp is characterised by high and rapid mortality, typically accompanied by the gross signs of yellowing of the cephalothorax and general bleaching of body colour. Yellowhead desease is a viral infection of shrimp and prawn which is lethal and contagious, killing shrimp quickly.

An initial period or exceptionally high feed consumption followed by abrupt cessation of feeding and increased mortality in the population (but not always seen). Lethargic or moribund shrimp accumulate at the pond surface and edges with very slow to erratic swimming behaviour. The region of the cephalothorax is noticeably yellowish due to the light yellow colour of the underlying and abnormally soft hepatopancreas (but not always seen). Overall body colour of shrimps always of abnormally light or bleached appearance.

No treatments currently exist

Signs may include : appearance of white, yellow or brown gills , yellowing of the cephalothorax and general bleaching of body and yellow, swollen digestive gland makes head appear yellow

Yellowhead virus (YHV) caused the disease. It is a positive-sense single-stranded RNA virus which is related to coronaviruses and arteriviruses. A closely related virus is the gill-associated virus (GAV), which is the type species of the genus Okavirus The cephalothorax of infected shrimp turns yellow after a period of unusually high feeding activity ending abruptly, and the then moribund shrimps congregate near the surface of their pond before dying. YHD leads to death of the shrimps within two to four days. YHV is highly infectious for most species of cultivated penaeid shrimp.