Impact of cyprinid herpesvirus 3 (Koi herpesvirus) on wild and cultured fish.

Abstract

Abstract Common carp is a widespread freshwater fish inhabiting lower and mid streams of rivers and shallow confined waters in Eurasia. Carp aquaculture in shallow, man-made ponds has a long history and now common carp is the most widely cultured freshwater fish species in the world. In many regions, carp aquaculture secures food for the population and carp ponds constitute characteristic elements in the landscape, which contribute to local biodiversity and water balance. Farmed and natural populations of common carp can be threatened by the cyprinid herpesvirus 3 (CyHV-3, syn. Koi herpesvirus (KHV)), the cause of KHV disease. Carp affected by this disease develop severe clinical signs and suffer from high morbidity and mortality. The infection was rapidly dispersed into naive populations by healthy appearing latently infected individuals. During initial outbreaks, the disease killed farmed carp in Europe, Israel and Indonesia as well as a high percentage of carp from natural populations in China, Europe, Japan and the USA. However, in subsequent years the number of carp mortalities declined in affected populations. In carp aquaculture, economic losses related to fish mortalities, reduced stocking density in ponds at risk of infection and trade restrictions incurred upon infected carp populations, are still significantly challenging the economic basis of carp farming. Possible control measures include disinfection of contaminated ponds by quick lime and re-stocking with virus-free fish, the development of effective vaccines and the breeding of disease-resistant carp lines.