Koi herpesvirus and carp oedema virus: Infections and coinfections during mortality events of wild common carp in the United States

Abstract

Koi herpesvirus (KHV; cyprinid herpesvirus‐3) and carp oedema virus (CEV) are important viruses of common and koi carp (Cyprinus carpio); however, the distribution of these viruses in wild common carp in North America is largely unknown. During the summers of 2017 and 2018, 27 mass mortalities of common carp were reported from four states in the USA (Minnesota, Iowa, Pennsylvania and Wisconsin), the majority of which were distributed across eight major watersheds in southern Minnesota. Samples from 22 of these mortality events and from five clinically healthy nearby carp populations were screened for KHV, CEV and SVCV using real‐time polymerase chain reaction (qPCR). KHV was confirmed in 13 mortality events, CEV in two mortality events and coinfections of KHV/CEV in four mortality events. Nucleotide sequence analysis revealed that the KHV and CEV detected here are closely related to European lineages of these viruses. While molecular detection alone cannot conclusively link either virus with disease, the cases described here expand the known range of two important viruses. This is also the first reported detection of KHV and CEV coinfections in wild carp populations.

First Evidence of Carp Edema Virus Infection of Koi Cyprinus carpio in Chiang Mai Province, Thailand

“…The most common behavioral abnormality of CEV infection in cyprinid fish is lying on the bottom of the ponds. Other clinical signs of infected fish include: lethargy, anorexia, swelling and necrotic gills, enophthalmos, and skin hemorrhages or skin ulceration [23][24][25][26]. Similar clinical signs were observed in the present episode.…”

“…Moreover, common clinical signs of infected fish are lethargy, anorexia, excessive mucus, skin hemorrhages with edema of the tissues, skin ulceration around the mouth and base of the fins, enophthalmos, and pale swollen gills [10,23]. Significantly, pathological lesions on vital organs such as gill hyperplasia and gill necrosis occur, leading to high mortality with dyspnea and hypoxia condition in infected fish [23,24].…”

Koi herpesvirus and carp edema virus threaten common carp aquaculture in Croatia

“…In recent years, carp edema virus (CEV), formerly described as a cause of high mortalities in koi carp juveniles in Japan only (Murakami, Shitanaka, Toshida, & Matsuzato, 1976), emerged as an important pathogen of ornamental koi and common carp in many European countries, namely in the UK (Way & Stone, 2013), the Netherlands and France (Haenen, Way, Stone, & Engelsma, 2014), Austria (Lewisch, Gorgoglione, Way, & El‐Marbouli, 2015), Germany (Jung‐Schroers et al, 2015), Poland (Matras et al, 2017), Hungary (Adamek, Baska, Vincze, & Steinhangen, 2018) and Serbia (Radosavljevic, Adamek, Miličević, Maksimović‐Zorić, & Steinhagen, 2018). Beyond Europe, apart from being an endemic disease in Japan (Oyamatsu, Hata, Yamada, Sano, & Fukuda, 1997), outbreaks were reported from koi carp in India (Swaminathan et al, 2016), China (Zhang et al, 2017) and South Korea (Kim et al, 2018), and from both koi and common carp in the United States of America (Lovy, Friend, Al‐Hussinee, & Waltzek, 2018; Padhi et al, 2019).…”

Mass mortality associated with koi herpesvirus in common carp in Iraq

“…Koi herpesvirus disease (KHVD), a serious disease affecting both wild and common carp species, is caused by the cyprinid herpesvirus 3 (CyHV-3) [ 1 ]. KHVD can occur on its own or as part of a coinfection alongside other viral agents such as carp edema virus [ 2 ]. Listed as a notifiable disease according to the International Office of Epizootics, KHVD first appeared in Germany in 1997 and soon spread to many countries in Europe, Asia, North America and Africa, causing huge losses in common carp and koi culture production [ 1 ].…”