Epizootiology, distribution and the impact on international trade of two penaeid shrimp viruses in the Americas.

Marine penaeid shrimp are effected by approximately twenty viruses, the majority of which were discovered as a result of their negative effects on aquaculture. In the Americas, infectious hypodermal and haematopoietic necrosis (IHHN) virus and Taura syndrome (TS) virus have had a significant negative impact on aquaculture industries and, in one instance, on a commercial fishery. Both viruses have become widely distributed as a consequence of the movement of host stocks for aquaculture. IHHN virus (IHHNV) causes catastrophic losses in cultured and wild Penaeus stylirostris. In marked contrast, P. vannamei is relatively resistant to IHHN but infection results, nonetheless, in poor culture performance. TS virus (TSV) is the 'mirror image' of IHHNV in its effect on P. stylirostris and P. vannamei. TSV causes catastrophic losses in P. vannamei, whereas P. stylirostris is highly resistant to TS. In the less than three years since the discovery of TSV in Ecuador in 1992, the virus has spread rapidly and caused massive production losses in most shrimp-growing countries in the Americas.