Tests for the presence of koi herpesvirus (KHV) in common carp (Cyprinus carpio carpio) and koi carp (Cyprinus carpio koi) in the Czech Republic

Abstract

An outbreak of koi herpesvirus (KHV) infection associated with high mortality of common and koi carp was recorded in the USA and Israel in 1998. At present, this disease is viewed as one of the most significant factors that can adversely affect common and koi carp breeds. The disease has spread worldwide including European countries neighbouring with the Czech Republic (CR), i.e. Germany, Poland, and Austria. To monitor the situation in the CR, samples were collected from a total of 138 common and koi carps in seven and eight locations in CR respectively, and were examined between 2005 and 2006. Locations owned by the major producers of common and koi carp were selected with respect of potential occurrence of the KHV virus. No records of increased mortality and morbidity were noticed there. Preferentially carps with non-specific symptoms of disease were sampled, often with isolated skin erosions. To obtain detailed picture about health condition of examined fish the bacteriological and haematological examinations were accomplished. The next part of the examined samples were carp and koi carp for export from professional breeders, imported koi carp and fish from breeds with increased mortality (45 and 21 fish in 2005 and 2006, respectively) The only virological testing was done in this case. The culture and PCR method, according to Gilad et al. (2002) showed negative results for virus KHV in all years. Retrospective investigation by PCR method according to Bercovier et al. (2005) showed positivity in five locations in 2005. In 2006, KHV virus was not detected in any of the selected locations. The aim of our study was to find out the presence/absence of KHV in selected locations and potential correlation of virological, bacteriological and haematological findings. The results of first testing for presence of koi herpesvirus indicates the necessity of regular KHV monitoring in the Czech Republic in the next period.