Koi Health - Information on Koi Herpesvirus

Koi Herpesvirus DIstribution in Japan

(pers.comm. M. Sano): KHV PCR tests are done since 2001. In May-June 2003 the first outbreak occurred in common carp and koi of 1-3 kg in a river in Okayama Prefecture, Western Japan. Oct 2003 acute mortalities occurred in Ibaraki Prefecture, Lake Kasumigaura (660 tons) en Lake Kitaura (200 tons), Eastern Japan. The water temp was 17°C. Phytoplankton bloom may have been a stress factor. In the mean time 22 metric tons were distributed from Lake Kasumigaura to 21 prefectures (Fukuda, pers.comm.). Mid Nov already 4 rivers were infected (Yoshimizu, pers.comm.). By end Nov 2003 mortalities reached 1200 tons in total. Clinical signs included severe gill necrosis and sunken eyes. There was new legislation in Japan since July 2003 (requirement of an infection free certificate). Ibaraki Prefecture has officially prohibited movements of common carp from the affected areas to other areas. All koi shows were cancelled for Nov 2003. By January 2004 23 of the 47 Prefectures of Japan were infected with KHV (Asahi Shimbun, 2004) and killed thousands of tons of fish. It threatens the USD 75 million ornamental carp industry of Japan further (Australian, 2003).(from Olga L.M. Haenen and Marc Y. Engelsma in International Workshop on Koi Herpesvirus2004)

June 2005 KHV _infected carp found in 42 of 47 prefectures in Japan (Iida, T, Sano)

June 2006 KHV reported in Niigata area, the most highly concentrated area of koi breeders (Isa, Hajime)