Historic emergence, impact and current status of shrimp pathogens in the Americas

Schematic of the major viruses of penaeid shrimp. The virions are drawn to scale; scale divisions are 20nm. IHHNV=Infectious hypodermal and hematopoietic necrosis virus; HPV=hepatopancreatic parvovirus; WSSV=White spot syndrome virus; BP=Baculovirus penaei, MBV=Penaeus monodon-type baculovirus; BMN=baculoviral midgut gland necrosis; TSV=Taura syndrome virus; IMNV=infectious myonecrosis virus; YHV=Yellow head virus; GAV=Gill associated virus; and LOV=lymphoid organ virus. A montage of photomicrographs of purified or semi-purified preparations of virions of some of the penaeid shrimp viruses shown above. The magnifications of the micrographs have been adjusted to illustrate the approximate relative sizes of each virus. Refer to Fig. 1 for the average size of each of the respective virions. 2% PTA negative stain. [Display omitted] ► Six of 8 OIE listed crustacean diseases are viral or bacterial diseases of penaeid shrimp. ► WSSV resistant lines of Penaeus vannamei, have been developed. ► Domestication of SPF/SPR stocks of P. vannamei led to its global dominance in shrimp aquaculture. Shrimp farming in the Americas began to develop in the late 1970s into a significant industry. In its first decade of development, the technology used was simple and postlarvae (PLs) produced from wild adults and wild caught PLs were used for stocking farms. Prior to 1990, there were no World Animal Health Organization (OIE) listed diseases, but that changed rapidly commensurate with the phenomenal growth of the global shrimp farming industry. There was relatively little international trade of live or frozen commodity shrimp between Asia and the Americas in those early years, and with a few exceptions, most of the diseases known before 1980 were due to disease agents that were opportunistic or part of the shrimps’ local environment. Tetrahedral baculovirosis, caused by Baculovirus penaei (BP), and necrotizing hepatopancreatitis (NHP) and its bacterial agent Hepatobacterium penaei, were among the “American” diseases that eventually became OIE listed and have not become established outside of the Americas. As the industry grew after 1980, a number of new diseases that soon became OIE listed, emerged in the Americas or were introduced from Asia. Spherical baculovirus, caused by MBV, although discovered in the Americas in imported live Penaeus monodon, was subsequently found to be common in wild and farmed Asian, Australian and African penaeids. Infectious hypodermal and hematopoieti