Prevalence and geographic distribution of infectious hypodermal and hematopoietic necrosis virus (IHHNV) in wild blue shrimp Penaeus stylirostris from the Gulf of California, Mexico

A histopathological survey of wild blue shrimp Penaeus stylirostris from th e Gulf of California, Sonora, Mexico, revealed the presence of infectious h ypodermal and hematopoietic necrosis virus (IHHNV). The survey performed at 39 sampling stations during August-September 1990, showed the prevalence o f IHHNV infection to be 46% in the upper Gulf zone and 26% in the central-l ower Gulf zone. The presence of IHHN virus was confirmed with the IHHNV-spe cific gene probe BA401 by means of in situ hybridization. Specimens of the Pacific brown shrimp P. californiensis (also known as yellowleg shrimp) and Pacific white shrimp P. vannamei, incidentally captured during the survey, were also analyzed and found to be infected by IHHNV. The survey demonstra ted that IHHNV had widespread distribution in a region where it had not bee n previously detected and, presumably, was not present before 1987. These f indings suggest that IHHNV has become established in wild populations of P. stylirostris, and perhaps in P. californiensis and P. vannamei, in the Gul f of California.