Relationship between White Spot Syndrome Virus infection and clinical manifestation in Indian cultured penaeid shrimp

The present paper describes three distinct forms of white spot syndrome outbreaks associated with White Spot Syndrome Virus (WSSV), among cultured penaeid shrimp (Penaeus monodon and Penaeus indicus)) of India. In a type I outbreak (acute to subacute), the tissue level severity of infection was moderate to high, significant mortalities occurred within 7-10 days, and the affected shrimp had prominent white spots on the carapace as the principal clinical sign. In a type II outbreak (peracute), the affected shrimp displayed massive reddening, the tissue level severity of infection was very high, and mass mortalites occurred within 2-3 days. Type III outbreak (chronic), had low tissue level severity of infection, white spots and reddening were absent, and the mortalities were spread over a duration of 15-28 days. The peracute form was more common in juveniles while acute to subacute and chronic forms were common in sub-adults and adults. Acute to subacute forms of the disease were observed in 60% of the outbreaks, while chronic and peracute forms were observed in 30 and 10% of the outbreaks, respectively. (C) 1998 Elsevier Science B.V. All rights reserved.