How Would You Know it's Chytrid?

We sometimes answer our phone and the voice on the other end says, "I just found a frog with that chytrid fungus" but that is seldom what the problem is. Its just all the media publicity that makes people think there is only one disease out there so this frog they found HAS to have chytrid. There a lot of disease problems around and sometimes they need to use some of the same symptoms to express themselves. For example, weight loss can be caused by a list of items including chytrid. Skin irritiation and excessive sliming can be caused by a suite of bacterial and fungal problems as well as chytrid. Curling toes and other nervous system damage can be caused by poisoning as well as disease.

It really depends on where you are as to the chances of your finding a sick frog that is being attacked by chytrid or having chytrid in your captive frogs. First of all, this disease is a cool climate pathogen. It prefers a temperature of 15C to 23C so if you are in a place that is experiencing these temperatures, it is possible that chytrid might have reached your region. So northern hemisphere folks should look for signs of chytrid during your autumn and winter (about October to about April. Southerm hemisphere folks should be vigilant from about April to September. The closer you are to the equator, the shorter your cooler season.

In Australia, the top end of the country is normally too hot for chytrid but there are 'windows of opportunity' in some places. On the tropical north coast, the high altitude mountain tops can be affected by chytrid for a large part of the year; the Tablelands plateau needs to worry during the winter months; and the lowland coastal plain has mostly escaped the onslaught, although our current winter will probably see new chytrid cases from a scattering of spots along the coast, including Cairns. Any place with high altitude areas will have more available growing time for chytrid than places near sea level.

So once you have established that you are in the right temperature range, how will you determine it might be chytrid and not one of the myriad of other frog disease problems killing frogs and toads? The symptoms on the body itself can be extremely cryptic - moreso than other subtle indications we see for each of the local diseases. It will be more likely that you'll notice the changes in the frog's/toad's behaviour.

• The fungus attacks the skin and then progresses to internal damage, mostly to the nervous system. The process of eating away at the skin is microscopic but apparently painful, and a frog will show the discomfort by adopting a rather "withdrawn" (tucked in) posture. When handled, it might cringe when affected skin is touched. They do not move around much at all and will be found sitting for long periods in one spot.
• Whether it is because of dehydration caused by the fungal interference of water intake through the skin or because the fungus might be felt on body as a burning sensation, frogs and toads with chytrid will spend pretty much ALL their time in the water, including remaining in open bodies of water during the daytime. They will sometimes stay there til they die and are then found floating dead in the water.
• After spending so much time in the water, a close look at their dorsal skin shows that it is still very dry and even stretched taught, but yet the body may be bloated from fluid retention This is because the disease affects calcium availability in the body so the calcium deficiency causes oedema (fluid retention).
• There may be redness under the body (ventral surface) and wet, discoloured crumbling bits of cuticle skin smearing off (see photo at right - normal sloughing is stringy and greyish), but this is not a reliable symptom for all species.
• There can be toe curling and other signs of nervous system damage such as a mild limb paralysis or a permanently tucked in head position (see photo above) but these are very terminal signs which are beyond help.

As the disease progresses, you'll notice that the frog/toad is losing weight but, if it has only just picked up the disease, the weight loss won't have started yet so don't use weight loss alone as a sign of chytrid. Frogs and toads do stop eating when they get this disease but this alone is not enough to determine chytrid as any illness will suppress appetite. Chytrid is also microscopic so if you see discolouration or other oddities on the surface of the skin, these are not chytrid but something else that will need attention.

Chytrid is an aquatic pathogen so it needs to have water to live. It can live in any body of water including a stream, a dam, a river, a pond, a ceramic water feature, a dog bowl - anything that holds water. It can be transmitted by anything that gets wet or moves water such as the runoff from rainy weather, on bird's feet, fisherman's waders, frog enthusiasts shoes and hands, collected plants, exchaging pond items with other pond owners, hikers walking through multiple puddles, and frogs moving throughout the neighbourhood looking for food and drink. Chytrid can be moved around with contaminated tadpoles, be they captive raised or wild caught.

All these things mean that there are steps YOU can take to help reduce the spread and carnage of chytrid fungus.

• If you have a frog pond in your yard, please consider draining it during the winter months. If the pond has no water in it during chytrid season, it won't be infected by chytrid and it won't spread the disease to every frog that comes to the pond. You can put other containers of water out for birds and frogs and these can easily be dumped down the sink and washed before refilling. Even if chytrid should be carried into one of these containers, you are eliminating it every time you change the water and disinfectant the container.
• Kids love to go down to the creek or drain to see what's there and often will rescue things such as tadpoles. Teach your kids how helping the environment sometimes means a few inconveniences for us, but these inconveniences can help save wildlife. During chytrid season, it would be best if they don't ride their bikes into any of the waterways they ride past. They should also be mindful about wading into the water in the local creeks unless they are wearing boots (this is a safety matter for them as well since broken glass is sadly a common inhabitant of our precious waterways). They should also remember that if they wander into one body of water, they should come home after that and not go to another creek or drain until they have washed their boots. These might seem like too much for kids to absorb but its not - they are sponges and will absorb whatever lessons they are provided with!
• If you should see a frog or a toad (yes, we collect sick cane toads for disease surveillance purposes) out in the open during the day, you can collect it and contact us. We are also setting up a local network of veterinarians who can receive frogs for us when you can get to our premises.
• If you are a pond owner, don't exchange fish, plants, tadpoles or other ornaments with other pond owners. If you have tadpoles in your pond which are overwintering, they can be moved to an aquarium and raised artificially until it warms up again.
• Ponds can also be treated with heat if you are able to obtain large enough aquarium heaters and this will prevent chytrid from establishing and get rid of it if it arrives but contact us to discuss this experimental method before trying it yourself. Likewise, you can also use the antifungal we use in treating chytrid in your pond but we should verify that you actually have a chytrid situation before you put something in your pond that doesn't normally belong there!
• If you engage in any recreational activities camping, bushwalking (hiking), and nature tourism, wash down your vehicle tires when you get back to the bitumen/paved road (this also helps reduce the spread of phytophora, another fungus that kills trees). Have a special pair of shoes for your outdoor activities which can be soaked in bleach after each outdoor excursion (bleach will also kill viruses so you'll be protecting the bush from all sorts of nasties).
• If you like to go freshwater fishing, wash your waders or other footwear down with disinfectant, bleach or betadine after each body of water you visit. If you collect bait or buckets of water from a fishing site, dump it back into the same body of water before leaving that spot, and rinse your bucket out with betadine (or at least very hot water if that's all you have available) before moving to another fishing spot. Collect new water and/or bait there. (A side issue is that frogs are protected wildlife and you should NOT be using them as bait!!!!)
• If you are a volunteer doing any sort of monitoring in the field, you should be practicing FULL DISINFECTION procedures which include your footwear, clothing and special showers before and after your trip. The outside and inside of your vehicle should be washed after any trip and especially before entering any protected estates such as World Heritage Area. You should be wearing gloves for anything you handle in the field and your gear and storage boxes need to be disinfected as well.

As we receive and verify more cases of chytrid in Far North Queensland, we will add to this list, but these are some of the suburbs/towns that we have received confirmed cases from (our cases are confirmed by James Cook University, DPI's Vet Diagnostic lab and the Registry of Wildlife Pathology). If you live near these locations, please keep a special lookout during the winter. Chytrid is highly contagious to other frogs so if we can save at least some frogs in these areas, there will be something left to breed next summer!

If you suspect the presence of chytrid on your property, please contact us QUICKLY. Chytrid can be cured in frogs but there is definitely a time limit. Once you have turned in a frog from your property that has been diagnosed with chytrid, we can provide you with ways you can help to reduce to the spread to other frogs you have.

We also have treatment instructions for those in remote areas who want to save frogs on their properties but please phone us to discuss whether it really is chytrid or another problem before you start treatment. The symptoms of disease in frogs are extremely cryptic and can easily be mistaken.

If you want more information generally about chytrid fungus, see the general chytrid page.

Last updated: May 7th, 2008