analysis alone is not sufficient to characterize viruses in the IHHNV complex. For example, IHHNV like lesions described in shrimp from Australia (Owens et al., 1992) did not react with a DNA probe developed from Hawaiian IHHNV, suggesting that these two types might also differ by 10% or more in DNA sequence (Owens, 1997). Indeed, work has shown that primer modification is required to detect Australian IHHNVand that it resembles most closely the type described from Madagascar (Krabsetsve et al. 2004). Very recent results suggest that some Australian and African shrimp samples positive for IHHNV are not infected with the virus but carry an IHHNV DNA fragment in their genome (Tang and Lightner, 2006). However, existence of the fragments suggests that the originating viral variants may also be extant in the respective geographic regions. Obviously, more research is needed to determine the range of variation of IHHNV types and any potential impact on the shrimp industry. A recent publication (Tang et al., 2003b)