(Other names: ranavirus disease, ranavirosis)
Description
Ranavirus is a disease caused by viruses of the genus Ranavirus. Susceptible animals include ectothermic species such as reptiles, fish, and amphibians. Ranavirus has been identified as the causative agent of disease in at least 175 species globally. During an outbreak, ranavirus can have a mortality rate of up to 90 to 100%, which can devastate local reptile, fish, and amphibian populations. As such, Ranavirus is considered a Notifiable Pathogen by the World Organization for Animal Health, meaning that this pathogen is of international concern.
To date, there are no documented ranavirus die-offs of reptiles, fish, or amphibians in Indiana; however, ranavirus has been discovered in the state, so future die-offs are possible.
Transmission
Transmission of ranavirus occurs through direct contact with infected animals, which can include contact during breeding events, predation, necrophagy, or incidental direct contact between an infected and uninfected animal. Indirect contact can occur through water and soils in which Ranavirus is present.
Humans also play a significant role in increasing ranavirus transmission by spreading the pathogen across a landscape, thereby increasing the chances of exposure. For example, infected live bait used by anglers can introduce the pathogen to previously unexposed fishing areas.
Clinical Signs
The first sign of a ranavirus outbreak often is a massive die-off (10+ individuals) of amphibians, fish, and/or reptiles over one to five days. Clinical signs that present in individual animals range from mild to severe hemorrhaging, typically around the hind limbs and/or vent opening. Behavioral signs include weakness, erratic swimming, lethargy, unusual gasping for air, and/or irregular buoyancy. In a post-mortem necropsy, animals infected with ranavirus may have fluid accumulation in the body cavity and hemorrhaging of the liver, stomach, and heart.
Wildlife Management Implications
Outbreaks of ranavirus pose a significant risk to reptile and amphibian populations throughout the state. You can help track outbreaks of this disease by reporting suspect mortality events to the DNR. If you encounter more than 10 dead reptiles, fish, or amphibians (including tadpoles) at a single location, or see several animals displaying signs of ranavirus, please report this event to Indiana DNR using the Sick or Dead Wildlife Report system.
There are also various ways that you can help prevent the spread of ranaviruses:
- Do not move soils or other materials (rocks, stones, shells etc.) from one site to another.
- Do not move reptiles, fish, or amphibians from one site to another.
- Disinfect your boat and other gear that encounters water or soils before moving to a new body of water.
Human Health Significance
Ranaviruses are not known to cause ill health effects in humans.
Additional Resources
- American College of Veterinary Pathologists: https://www.acvp.org/page/ranavirus
- Cornell Wildlife Health Lab: https://cwhl.vet.cornell.edu/disease/ranavirus
- Gray, M. J., Miller, D. L., & Hoverman, J. T. (2009). Ecology and pathology of amphibian ranaviruses. Diseases of aquatic organisms, 87(3), 243-266.
- Lesbarrères, D., Balseiro, A., Brunner, J., Chinchar, V. G., Duffus, A., Kerby, J., ... & Gray, M. J. (2012). Ranavirus: past, present and future.
- Price, S. J., Ariel, E., Maclaine, A., Rosa, G. M., Gray, M. J., Brunner, J. L., & Garner, T. W. (2017). From fish to frogs and beyond: Impact and host range of emergent ranaviruses. Virology, 511, 272-279.