Taura syndrome in Pacific white shrimp Penaeus vannamei cultured in Taiwan

Mass mortality of cultured white shrimp in southern Taiwan was diagnosed as an outbreak of Taura syndrome (TS). From late 1998 to early 1999, 90% of t he shrimp ponds were abandoned at 30 to 45 d after stocking post larvae fro m Ecuador and elsewhere. The shrimp began to die within 2 to 3 d after they stopped feeding. There were no other gross signs, except that some affecte d shrimp had reddened tails. Histologically, multifocal necrosis of the cut icular epithelium was the main lesion. The necrotic foci contained pyknotic and karyorrhectic nuclei, and many lightly and densely stained intracytopl asmic and intercellular, spherical inclusions. By transmission electron mic roscopy, small, icosahedral, picorna-like virus particles 30 nm in diameter were seen. Taken together, the observations resembled those for outbreaks caused by Taura syndrome virus (TSV). It is assumed that TSV was transferre d to Taiwan via contaminated post larvae and spawners from epizootic areas. This is the first report of a TS outbreak in Taiwan.