Infectious Hypodermal and Hematopoietic Necrosis

Infectious Hypodermal and Hematopoietic Necrosis (IHHN) is a viral disease of penaeid shrimp that causes mass mortality (up to 90%) among the Western blue shrimp (Penaeus stylirostris) and severe deformations in the Pacific white shrimp (P. vannamei). It occurs in Pacific farmed and wild shrimp, but not in wild shrimp on the Atlantic coast of the Americas. The shrimp-farming industry has developed several broodstocks of both P. stylirostris and P. vannamei that are resistant against IHHN infection.

The disease is caused by a single-stranded DNA virus simply called "IHHN virus", the smallest of the known penaeid shrimp viruses (22 nm).