moldy orangesThe Fungus Among Us...

By Sarah Courchesne, CFW Staff Member

Many of the animals we treat at the Center for Wildlife have obvious injuries; they’ve been hit by cars, caught by cats or otherwise suffered some trauma. While these cases can be difficult, and even impossible, to heal or repair, the truly troublesome cases are the ones where the reason for an animal’s illness is invisible. All we know for sure is that the animal isn’t quite right, and maybe we suspect an infection, but even that leaves us a world of possibilities. When you (and here I assume you are a human living in the developed world) or I get sick, usually a virus or bacterium is responsible. Both of these are potential invaders in our animal patients, but in free-roaming (and flying) wildlife, we must always consider two additional possibilities: parasites, and fungi. The former are ubiquitous in wild animals and usually don’t cause significant disease. The latter, however, can be nearly undetectable and are often deadly.

Fungi come in two forms: molds (like mushrooms and that green fuzz on your old bagels), and yeasts (the reliable organism we count on to make bread rise.) So, why worry about such banal, and even edible, items? It all depends on the delicate balance of the normal and abnormal organisms that every animal harbors. Our patients are often weak, sick, and under the overwhelming stress of being kept inside near a throng of predators (read: people). With an immune system already stretched thin by so many demands, a fungal infection can often get just the toehold it needs.pigeon candida

Fungal spores are everywhere and we all breathe them in everyday. One particularly common species, Aspergillus flavus, is probably hanging out in your refrigerator right now. A few spores eaten or inhaled now and then won’t hurt a healthy animal or person. But if a sick animal breathes them in, or if a huge number of spores are inhaled (as would happen in an animal housed in a dirty cage full of wet shavings, for instance) an active infection may result. All of the animals at the Center for Wildlife are kept on clean, dry bedding to minimize the risk, but some animals, like seabirds, require even more precautions. Loons, gannets, eiders, any bird that usually spends its days out on open water is especially susceptible to Aspergillus infections while in captivity. We try to move these birds into outdoor enclosures as soon as possible to maximize ventilation and keep their exposure to the fungus low. We also give a daily antifungal medication to all seabirds as a preventative measure. Why do we give medicine for a disease the birds don’t even have yet? After all, we would never give an animal antibiotics just because it might develop a bacterial infection. The answer is twofold: Aspergillosis is insidious and nearly impossible to detect in its early stages, and once the infection is established, treatment is nearly impossible as well. So prevention is the goal with this fungus, just as it is with a related species, the yeast, Candida albicans.

Candida albicans is a normal resident in birds’ digestive tracts. It’s usually a model citizen, coexisting peacefully alongside all the other bacteria and assorted organisms in the gut, but if those neighbors are disrupted or eliminated, Candida will happily move in on the new territory. Typically we see this in a bird that has been on antibiotics; the bacteria are killed and Candida suddenly has no competition and overgrows with potentially deadly consequences. A larger scale version of this interaction is probably happening right now in my fridge; an open jar of strawberry-rhubarb jam is sitting on a shelf. Jams and jellies have so much sugar in them that even bacteria can’t survive…but a fungus can. Without the usual fast growing bacteria for competition, the fungus can spread out, growing slowly but steadily until a month from now when I open the jar and quickly lose my appetite for toast. Candida infections are particularly common in young animals and can occur in both wild and pet birds. The infection is treatable, but the more important thing is finding out what set the stage for the usually reclining fungus to make a grab for power.

Prevention is the goal with fungal diseases, and we try to ensure optimum conditions for all our patients. When we can’t prevent , we aim not only to treat, but to learn from each case how better to house animals, clean our facilities and minimize the risk. It takes constant vigilance and we are always learning. We constantly gain new perspectives here at the Center, as perhaps you have on the drama unfolding in your own kitchen. Think of us, or rather, think of the seabirds, next time you savor a nice peanut butter and jelly sandwich.


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