Effect of Water Temperature on Mortality and Virus Shedding in Carp Experimentally Infected with Koi Herpesvirus

Common carp Cyprinus carpio were experimentally exposed to koi herpesvirus (KHV) under water temperature regimes ranging from 16 degrees C to 28 degrees C. Fish maintained at 16 degrees C, 23 degrees C and 28 degrees C died due to infection at 21-52, 5-20 and 7-14 days post-virus exposure (dpe), respectively. Cohabitation experiments in which KHV-infected common carp were kept with naive koi carp revealed that infectious virus was continuously shed from the infected common carp for 34 days (7-40 dpe) at 16 degrees C, for 14 days (1-14 dpe) at 23 degrees C and for 12 days (3-14 dpe) at 28 degrees C. The relatively extended duration of virus shedding observed at 16 degrees C suggests the potential risk of infection from fish maintained under low-temperature conditions as a source of viral inocula.