Epidemiologic modelling to predict the disease outcomes for carp populations in Australia are important to predict the efficacy of KHV for biocontrol (Durr et al 2019). Key aspects of KHV delivery into a target carp population will be the time of year that infected fish are released and understanding the most significant ways in which the virus is spread between fish. One mechanism for virus delivery proposed is the introduction of “trojan” carp into the target population. Depending on the temperature at which they are held, carp may be subclinically infected and later go on to shed KHV and develop disease when the water temperature is increased (Sunarto et al., 2019). A release pathway that uses trojan carp that are infected with KHV by intraperitoneal (IP) injection requires knowledge of the survival time and detailed excretion dynamics (including at and after death) under different conditions for virus dose, water temperature and age/health/life history of the fish.
Modelling highlights the important influence of transmission dynamics on disease outcomes. A key for KHV models is to determine if direct transmission (i.e. requiring direct fish-to-fish contact) is more important than indirect transmission (whereby naïve carp can be infected by KHV shed into the water). This will determine the relative efficacy of KHV biocontrol during carp aggregation (Durr et al., 2019).
The present study will use a laboratory infection model to evaluate KHV replication and shedding in injected carp. Further, the relative importance of direct and indirect transmission of KHV will be compared. This will inform epidemiologic models to improve predictions and management of a controlled KHV release.
References
Sunarto A., Moody, N.J.G. and Durr, P.A. Essential studies on cyprinid herpesvirus 3 (CyHV-3) prior to release of the virus in Australian waters: Seasonality studies. FRDC. Canberra.