Can shade cloth help prevent aspergillosis?

One of our goals at the OWCN is to conduct research to improve our husbandry and medical practices. These investigations ensure that our protocols optimize our rehabilitation success. To this end, Greg Massey, Christine Fiorello, and I spent the past weekend in San Pedro at the LA Oiled Bird Care and Education Center performing a research project. We collected data to compare the efficacy of shade cloth versus sheets as a visual barrier for birds housed in soft-sided pens. The rationale for this project goes back a ways, starting with a nasty fungus…

Among the many challenges in seabird rehabilitation is their susceptibility to Aspergillus, a fungus that is ubiquitous on land but rare at sea. Many healthy animals are exposed regularly and their immune systems are able to successfully combat infection. However, animals that are rarely exposed to the fungus and animals with compromised immune systems (oiled seabirds fall into both of these categories) are more susceptible to infection. For example, immunocompromised humans, such as those with AIDS or on chemotherapy, are highly susceptible. Aspergillosis, the disease caused by infection with Aspergillus spores, is extremely difficult to treat and is often fatal. Prevention is the best (and perhaps only) option.

Although there are medications that are used prophylactically to prevent aspergillosis, reducing the concentration of Aspergillus spores in the environment is crucial to successful prevention. The fungus likes to grow in warm, moist environments. Research from human hospitals has shown that sheets and bedding harbor many spores. In addition, researchers at oiled bird care facilities have found Aspergillus in the air throughout the facilities and even in the air above outdoor pools housing pelagic birds. Increasing ventilation is an easy way to decrease the concentration of these spores in the air.

During stabilization and drying, oiled birds are housed indoors in soft-sided, net-bottom pens. The top of the pen is covered, usually with a sheet, for several reasons: to prevent escape, to keep in heat, and to create a visual barrier. As you can imagine, these warm pens can provide a very hospitable environment for Aspergillus. The pens need to be warm in order to keep the birds alive; however, the risk of Aspergillus infection could be reduced if the ventilation were improved.

During his time as Assistant Director of OWCN, Greg Massey compared ventilation in soft-sided pens covered by sheets, blankets, and shade cloth. He found that the shade cloth provided much better ventilation with only a 3° F decrease in temperature. These findings indicate that a bird drying in a pen covered by shade cloth would be exposed to a much lower concentration of Aspergillus spores without increasing drying time or compromising heat retention.

The next step in this study was to investigate the quality of the visual barrier provided by shade cloth. Would birds become more stressed when housed in pens covered by shade cloth rather than a sheet? This past weekend, we collected data on the stress levels of three common murres and three western grebes housed in soft-sided pens with sheet and shade cloth coverings. We will use the video recordings of behavior as well as biological indicators such as corticosterone levels and white blood cell counts to compare stress levels of each individual bird when housed under each type of pen covering.

Many thanks to the IBRRC staff including Julie and Adam, and volunteers, including Yoch and Carol, for all of their help! And, of course, our gratitude to the birds for helping us to improve our care of oiled wildlife. The birds in this study are rehabilitation patients on the road to recovery, and so we’re thankful that they helped us for a few minutes before heading back out into the wild! We’ll keep you posted on our efforts as we continue this research.

– Emily

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