Ranavirus,
the Amphibian Apocalypse,
Approaches the Accotink Watershed
Ranavirus has devastated amphibian populations worldwide - now it is here.
In May, 2015, Old Colchester Park and Preserve experienced a wood frog tadpole die-off and subsequently, tadpole samples submitted to the USGS National Wildlife Health Center returned a positive result for a strain of ranavirus. This result follows a Smithsonian study conducted in 2014 that returned an "unconfirmed positive" result for the same population. Some other parks in the Northern Virginia area also participated in the 2014 Smithsonian study, and some of these also returned an "unconfirmed positive result." With confirmation of the virus at Old Colchester, I urge you to take precautions to protect the wildlife populations in your parks and in the region to the extent possible. Parks that have amphibian populations or susceptible rare animals such as wood turtles should take care to prevent spreading the disease. In addition, parks with a lot of foot traffic in amphibian habitat, school groups, citizen science work, etc. should also take precautions.

As you may know, ranavirus is a disease that affects amphibians, reptiles and fish. It has never been known to infect humans. The virus varies greatly in lethality, infection rate and symptoms. Frog tadpoles, for example, show blood and lesions on the belly and around the hind limb buds and are usually only symptomatic during their development when hind limb buds are forming. It is possible and likely that the virus has been present in the area for many years but relatively little monitoring has been done in Northern Virginia.

Options for management of ranavirus:

  1. There is no cure or direct treatment for the virus or infected animals.
  2. The best actions to take are to prevent spreading of the disease.
    1. Disinfecting boots, nets, containers and other gear before entering parks, vernal pools and ponds is the best prevention measure.
    2. This protocol is a widely used standard: http://fishandboat.com/ais/NEPARC_Disinfection_Protocol.pdf
    3. Public information and/or signs at heavily trafficked parks may be appropriate. For example, "Help protect our wildlife by disinfecting your boots".
  3. Monitor wildlife populations to observe long-term trends. For example, amphibian egg mass counts and turtle surveys can provide a picture of population change.
  4. Testing - Diagnostic testing is recommended if you witness a "mortality event" which is generally considered 5 or more dead individuals in the same population.
    1. An excellent resource is the National Wildlife Health Center (NWHC).
    2. Testing may be done at no cost if determined to be a mortality event of interest to the NWHC.

    Here is a good resource for further information: http://link.springer.com/book/10.1007/978-3-319-13755-1 .

    The Virginia Department of Game and Inland Fisheries can also provide information

    - Owen Williams, Natural Resource Specialist, Fairfax County Park Authority