Diagnostic case report: Disease outbreak induced by CyHV-2 in goldfish in China

Abstract

A lethal disease of goldfish (Carassius auratus) afflicted ornamental fish farms in Beijing in 2018, causing severe financial losses. Morbidity and mortality are restricted to goldfish and occurred in spring and autumn, when water temperature was between 15 and 28 °C. Moribund goldfish from ornamental fish farms were tested for Cyprinid herpesvirus 2 (CyHV-2) by polymerase chain reaction (PCR) and real-time PCR using the viral polymerase gene followed by sequence analysis. The polymerase gene-specific product shared 99.10% nucleotide sequence identity to the published sequence of CyHV-2. Histology and electron microscopy showed that the moribund fish had severe necrosis in the gill and kidney and herpesvirus particles were demonstrated by Transmission Electron Microscopy(TEM). We infer, from these findings, that CyHV-2 might be transferred systemically via blood circulation system and that goldfish herpesviral hematopoietic necrosis is likely to be an important or serious infection disease for goldfish farms in this region of China.