How do fish get infected with KHV?

As you already know that the KHV disease is caused by a virus; therefore, a contact with the virus is required for infection. According to reports available, there are a variety of sources for KHV spreading.

Figure 2: The sources for KHV spreading



A. Infected fish: As long as a fish is infected, no matter if the fish is showing symptoms and if the viruses are small in number, KHV can ruthlessly spread out. KHV was presumed to invade vulnerable fish through gills, because viral DNA is firstly detected in gills in many cases. Yet, Costes et al. proclaimed that KHV is transmitted by a “skin-to-skin” mode when infected fish rubbed other individuals or objects. Uninfected fish can also get infected by pecking skin lesions off or droppings from infected fish.

B. Carriers: Researchers applied various detection methods to support that KHV has a wider range of host besides koi and common carp. Goldfish (Carrassius auratus), Crucian carp (Carassius carassius), grass carp (Ctenopharyngodon idellus), and tench (Tinca tinca), seemed to carry and spread KHV, although all appear not to be affected KHV.

C. Water and mud: KHV remains infectious in water and mud for at least 4 hours and up to three months in a water body according to the report by Minamoto et al. in 2008. Water from the Yura River which had a KHV outbreak in one section was collected for examination. High levels of KHV were still detected after 3 months.
D. Other media: Anything, such as a net or a filter, which had contact with the virus, could possibly transmit the virus.



Bibliography

Costes B., Sta;om Raj V., Michael B., Fournier G., Thirion M., Gillet L., Mast J., Lieffrig F., Bremont M., Vanderplasschen A. (2009), The major portal of entry of koi herpesvirus in Cyprinus carpio. Journal of Virology, vol. 83 no. 7, 2819-2830

El-Matbouli M., Saleh M., and Soliman H. (2007), Detection of cyprinid herpesviurs type 3 in goldfish cohabiting with CyHV-3-infected koi carp (Cyprinus carpio koi), Vet Rec vol. 78, 23-28

Hartman K.H., Yanong R. P. E., Pouder D. B., Petty B. D. Francis-Floyd R., and Riggs A. C. (2004). Koi herpesvirus (KHV) disease, Fact sheet VM-149, Extension service, Institute of Food and Agricultural Sciences, University of Florida 2004

Pokorova D., Vesely T., Piackova V., Reschova S., and Hulova J. (2005), Current knowledge on koi herpesvirus (KHV): a review. Veterinary medicine-Czech, vol. 50(4), 139-147