Genetic Relatedness of Infectious Hypodermal and Hematopoietic Necrosis Virus Isolates, United States, 2019.

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is a nonenveloped, linear, single-stranded DNA virus belonging to the family Parvoviridae and is a World Organisation for Animal Health (OIE)-notifiable crustacean pathogen. During screening of Penaeus vannamei shrimp from 3 commercial shrimp facilities in the United States for a panel of OIE-listed (n = 7) and nonlisted (n = 2) crustacean diseases, shrimp from these facilities tested positive for IHHNV. Nucleotide sequences of PCR amplicons showed 99%-100% similarity to IHHNV isolates from Latin America and Asia. The whole genome of the isolates also showed high similarity to type 2 infectious forms of IHHNV. Phylogenetic analysis using capsid gene and whole-genome sequences demonstrated that the isolates clustered with an IHHNV isolate from Ecuador. The detection of an OIE-listed crustacean pathogen in the United States highlights the need for biosecurity protocols in hatcheries and grow-out ponds to mitigate losses.