The "Respiratory/Nervous System" Disease
Fungi Can be Elusive Although Their Effects Aren't!
In July 2002, something new and highly contagious arrived in the Cairns Frog Hospital. We suspected chytrid but it wasn't. We then obtained some positive results for Mucor amphibiorum but several hundred frogs came in with respiratory symptoms and M. amphibiorum does not have a respiratory component. Since it first arrived, we have received well over 1,500 frogs with the new disease (we bought a very expensive biological air filter to handle it!) and these have come from an area stretching from Gladstone to Thursday Island in the Torres Strait. We have had reports from other areas such as northern NSW and we've seen TV footage of Northern Territory frogs that looked suspicious but the animals have not yet been sent to Cairns for confirmation.
The collection of symptoms we are seeing with the new condition are consistent with a fungal disease and there are other species in the Mucor genus that match the symptom profile as well as some species in the Fusarium, Rhizomucor,and Rhizopus fungal genus'. However, we have had difficulty getting this widespread pathogen identified - the disease is attacking the nervous system so standard histology does not detect that anything is wrong. The disease also appears to be a mycotoxin and special equipment is used to find and identify toxins in the body (such as a gas chromatograph) but those few labs who have such equipment don't want to do the testing for us.
Examples of nervous system irritation: leopard spots to the far left and bottom; and a shift in normal pigmentation from emerald green to a greyish-brown. We have even collected individuals who have become entirely greyish-white! The normal colour of this species is emerald green.
We have ordered cultures on the tanks themselves hoping that the pathogen might be easier to find outside the body.
So far, the experimental cultures (done by DPI's diagnostic lab in Townsville) have revealed the presence of several fungal species which fit the profile.
When we have the funding, work will continue to isolate which of these might be the cause of the outbreak that has been causing frog and toads deaths here since July 2002.
The fungal species most consistently cultured from frog tanks and cane toad skin were:
- Trichosporon cutaneum
- An unidentified species of Mucor
- An unidentified species of Curvularia
- An unidentified species of Fusarium
We have been told that ID to species level will require molecular methods and we have received a quote of $2,000 to pinpoint the three species above (we don't have that kind of money). However, we have shortlisted a species of Fusarium as the prime target as Fusarium has been positive in all the specimens we have sent to the lab in recent years that also had the clinical symptoms of this disease.
Until such time as we can get a toxicology lab to confirm the ID of this pathogen, we would like to present the "new" collection of symptoms in the species we have seen them in so far. If you live in a part of Australia or elswhere that has experienced severe drought, you should be on the lookout for these symptoms as they MIGHT indicate this new fungal problem!
All species of frogs and toads seen exhibit lethargy, sitting out in open during day and increased greyish-white skin sloughing on the feet and legs. All lose weight rapidly. The frogs demonstrate breathing changes in that rapid, shallow panting can be seen when looking at the sides of the abdomen (in other words, don't judge the breathing by the chin area - look at the abdomen behind the elbow from the sides or top). If a frog dies and is opened for examination or preservation, at least one lung will be observed to be have expanded to more than double its normal size (distended). In cane toads, both lungs are grossly inflated and occupy the entire body cavity.
Additional symptoms by species are:
Common Green (White's) tree frog (Litoria caerulea):
Roth's tree frog (Litoria rothii):
Graceful/Dainty tree frog (Litoria gracilenta):
White-lipped tree frog (Litoria infrafrenata):
In the early stages:
As the condition advances:
In very advanced cases:
Cane Toads (Bufo marinus):
If you live in an area that is drought affected, be on the lookout for frogs and toads with the symptoms above.
If you find something, please bring it to your nearest frog group, museum or university so that it can be tested for Fusarium and other drought tolerant fungi which might exist in your area.
Use disposable gloves or a plastic bag on your hand and don't touch anything else until you have disinfected your hands with betadine solution or Microshield 4.
Mucor and the mystery fungus described above are highly contagious to other frogs and toads. If you are near an airport in Queensland which has flights to Cairns, you can contact us about sending the frog/toad up to us for confirmation of its condition.