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Frog Friday: Preventing the Spread of Amphibian Diseases

Amphibians face a wide range of threats from habitat loss to pollution. But the most serious threat that has emerged over the past few decades is disease. Since the 1970’s, scientists have noticed a rapid decline and in some instances the extinction of several species of frogs around the world. Among those species that have gone extinct in recent years are Costa Rica’s Golden Toad (Incilius periglenes) and Australia’s Southern Gastric-brooding Frog (Rheobatrachus silus).

The culprit of these extinctions across the globe was identified as the fungus Batrachochytrium dendrobatidis, or more commonly referred to as “chytrid” or “Bd”. This fungus has swept through areas in central America and the western United States like the Black Plague, killing thousands upon thousands of frogs in its path. Unfortunately, scientists were unable to do much of anything, so they documented the disappearance and collected healthy specimens for captive-breeding programs, such as the Amphibian Rescue & Conservation Project in Panama. Fortunately for Virginia, the disease (chytridiomycosis) associated with a chytrid infection doesn’t appear to be causing problems in the Commonwealth. However, we do have concerns about other amphibian diseases.

In the eastern United States, ranavirus infections have been attributed to localized die-offs of wood frogs and other vernal pond breeding amphibians. Ranavirus is a group of highly infectious viruses that can often be deadly to cold-blooded wildlife, particularly in the case of aquatic species, in which mass die-offs can occur.

 

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Hemorrhaging, as seen on the belly of this Green Frog tadpole (above and at left), is a sign of ranavirus infection. Photo credit: Kimberly Terrell, Ph.D

 

 

 

 

 

 

 

 

In response, the Virginia Department of Game & Inland Fisheries (DGIF) participated in a 2014 regional investigation into the prevalence of this virus. Fortunately, the results of this study showed that it was not widespread in Virginia.

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Sampling for ranavirus during the 2014 regional investigation. Photo credit: Scott Smith.

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Processing of samples during the 2014 regional ranavirus investigation. Photo credit: Scott Smith.

 

 

 

 

 

 

 

 

 

Amphibian conservationists have recently focused on a newly emerging disease “across the pond” in Europe. The Fire Salamander (Salamandra salamandra), once widespread and common in many parts of Europe, suddenly disappeared from large areas of its range. A newly emerged strain of chytrid known as Batrachochytrium salamandrivorans  was discovered as the culprit. With years of experience gained through researching Bd, scientists were able to quickly identify the vectors of this new strain. The identified hosts of this fungus are three species of Asian newt and salamander popular in the pet trade: Chuxiong Fire-bellied Newt (Cynops cyanurus), Japanese Fire-bellied Newt (Cynops pyrrhogaster), and  Tam Dao Salamander (Paramesotriton deloustali).

What can you do to help prevent the spread of disease?

  • Never release pet frogs or any other animal into the wild. The spread of these diseases has been largely attributed to the international trade of amphibians as pets. These exotic species have naturally evolved immunities in their native habitats. But when they are released into nonnative habitats and are carrying exotic pathogens, the impact can be catastrophic.
  • Between explorations of ponds, vernal pools, or other amphibian habitats, disinfect boots and any other field equipment used with a 3% bleach solution. Click here for a detailed cleaning procedure by Northeast Partners in Amphibian and Reptile Conservation (NEPARC). Following this protocol will help avoid an inadvertent spread of pathogens as you travel from one field site to another.
  • If you observe any amphibian die-offs, please report it the Department of Game & Inland Fisheries at  dgifweb@dgif.virginia.gov.

 

This article is presented as part of our year-long Virginia is for Frogs campaign. Please visit the campaign webpage to learn more about Virginia’s 27 frog species and ways that you can become involved in their conservation. Are you an educator? Check out the Virginia is for Frogs Teacher’s Corner for frog-related lesson plans and activities.

  • August 21, 2015