Yellow fungus disease in Bearded dragons is an aggressive, fungal infection that affects the outer and deeper skin layers. If not treated early, Yellow fungus can be deadly to Bearded dragons.
Yellow fungus disease is caused by skin-eating fungus called Nanniziopsis vriesii. Although much information is lacking, it is known that this fungus has more than one form and that the Chrysosporium anamorph of N. vriesii as (aka CANV) has been identified on infected skins of Bearded dragons and other reptiles. When present, the fungus is found on the outer and deeper layers of the skin. Nanniziopsis vriesii is usually an aggressive grower and can quickly start to penetrate and eat tissues under the skin too.
Although Yellow fungus is aggressive in nature, skin lesions often only become visible some time (weeks to months) after the infection started. Poor hygiene, incorrect husbandry, and other stress factors are often the reason for instigating the disease.
Signs of Yellow fungus on Bearded dragons
Yellow fungus affects areas of the skin and scales of Bearded dragons. Apart from other common signs of disease (e.g. anorexia, listlessness, lethargy, and dehydration), Yellow fungus disease can also be suspected by many specific signs.
Initially, the skin will become discolored and brittle. Multiple, small, or large patches of skin can be affected. Typical skin discoloration includes yellowish, brownish, and greyish. Any area of the body can be affected, but areas around the mouth, joints, and other moveable areas are often more affected.
Infected individuals might experience irregular, more-regular, and/or incomplete skin-shedding cycles. Shredded skin will often include dark, thickened areas and scales underneath shredded areas might appear dull and greyish in color. Also, see how should your Bearded dragon shed for more information.
As the disease progress, affected patches will start to enlarge and spread. During late disease, large painful sores form where areas of the skin break and fall off. Affected areas will enlarge/swell, turn black, and essentially begin to rot away. The revealed tissue is often swollen and inflamed and extremely sensitive. Smaller, non-healing sores (also called trouble spots) are also often seen. Badly affected limbs and tails often fall off.
How do Bearded dragons get Yellow fungus disease?
Because Yellow fungus disease in Bearded dragons can take a long time (weeks to months) to develop, the cause or origin of infection is often unknown. Yellow fungus organisms are often identified in conditions where there are:
- incorrect ultra violet (UV) exposure
- poor hygiene
- poor husbandry conditions
- overcrowding
The fungus itself can also be transmitted from one Bearded dragon to another. If a non-infected Bearded dragon comes in direct contact with an infected one, the Yellow fungus can be easily transmitted. Yellow fungus infection can also spread indirectly through either direct contact with cage furniture that was previously used by an infected Bearded dragon or being handled by a person that handled an infected Bearded dragon.
Yellow fungus disease can be introduced to non-infected Bearded dragons if proper quarantine measures have not been applied. Also, see Bearded dragon quarantine for more information.
Treating Yellow fungus disease in Bearded dragons
Not all cases of Yellow fungus disease will be treatable. The successful treatment of Yellow fungus disease can take a long time and is dependent on the correct diagnosis. Early, milder infections have a better prognosis of curing. The prognosis is also dependent on the location of the infection.
Treatment of Yellow fungus disease should be done under the guidance of an experienced reptile-friendly veterinarian. Veterinary treatment for Yellow fungus disease will likely include debridement, scheduled antifungal medications, ointments, and medicated baths.
At home, cleaning/disinfecting the environment with veterinary-grade disinfectant and isolation from other Bearded dragons will also be advised.
Is Yellow fungus disease dangerous to humans?
Although Yellow fungus disease is mainly considered to be a reptile-only pathogen, there is mention of reports where humans were infected. Fungal infections have the ability to affect people with weak immune systems (e.g. elderly people, babies, people with HIV and certain cancers, and patients undergoing chemotherapy).
Irrespective of the risk, Bearded dragon handlers are always advised to take responsible hygienic precautions. Always wash your hands before and after working with Bearded dragons (and any other reptile), their food, and/or their cage (furniture/substrate). Also, see correct Bearded dragon handling for more information.