All Cooped Up: Aspergillosis
Reading Time: 4 minutes
What is it? A respiratory disease caused by mold spores.
Causative Agent: Most often the mold species Aspergillus fumigatus, but can be caused by other molds as well.
Incubation period: 2-5 days
Disease duration: Usually acute, but can become chronic
Morbidity: Noncontagious, though birds in the same living condition will also be at risk.
Signs: Difficulty breathing, fever, lack of appetite, weight loss, and listlessness.
Diagnosis: Through clinical presentation and gross lesions mainly, but a histological examination of fungal elements observed in the lungs and air sacs is more definitive.
Aspergillosis, also known as mycotic pneumonia, is a fungal disease resulting from the inhalation of mold spores. This disease can affect most animals, including humans. Spores are inhaled from contaminated bedding, feed, dust, or even air ducts and hatching equipment. Once inhaled, the mold aggressively attacks the respiratory tract of the host, causing an array of nasty but expected symptoms.
Any kind of inhaled pathogen can cause inflammation in the lungs, which is going to lead to mucous production and difficulty breathing. Birds will pant rapidly with an open mouth. Once the host’s immune response recognizes an infection, body temperature rises. Fevers occur when the host is attempting to kill off the pathogen because a higher body temperature is often enough to handle many infections, however this is not the case with Aspergillosis.
Animals struggling to breathe naturally expend extra energy, and soon the host will not seek out food or activity as it attempts to fight off the infection. Increased metabolic demands coupled with a lack of appetite bring about rapid weight loss.
Young birds during the first few weeks of life are infected more often, leading to the third moniker of this disease: brooder’s pneumonia. Chicks are more at risk not only because of an immature immune system, but because they are in environments where these molds are most likely to grow. Brooders are warm, often humid, and high in ammonia from feces, creating a great environment for the mold to flourish.
Older birds who are exposed to the disease are more likely to survive, but as a result, are also more likely to develop the chronic form of the disease. The chronic form can exhibit as the typical respiratory complications with added blindness and neurological issues. Generally, the acute form only causes these complications if the spore exposure load is high.
A postmortem examination done at home or by a vet and will reveal grey or yellow plaque and nodules in the lungs and air sacs, and in severe cases in the trachea. These will be visible to the naked eye and grow as large as a few centimeters. The plaque may also be seen in the intestines and liver. The lungs may seem congested and swollen.
Aspergillosis does not spread between birds, but several members of the flock can get this disease at once. Environmental factors are the largest cause of this disease followed by food quality. Not cleaning the coop often or well enough can help the mold grow, as well as poor ventilation and wet environments. When bird feed is stored long term or in an unprotected area it can get wet, mold may also form.
If an outbreak occurs in a brood of meat birds meant for consumption, infected chicks may appear to recover or not have the disease at all, only for owners to find signs of it during processing. If a bird has any signs of this disease, they are not safe for eating and the meat should be disposed of safely.
There is no clinically effective treatment for aspergillosis. Most generally in chickens, the bird succumbs to the infection or spontaneously recovers. Supportive therapy is helpful for recovery, and practices such as separation, removal from the environment, stress reduction, and encouraging hydration can have a positive impact on the bird. Once they have respiratory symptoms, however, survival is rare.
In addition to supportive therapy, pet birds have seen some benefits with added fluids and antifungal drugs. However, this type of treatment is costly and prolonged and is generally not a viable option for farmers unless the birds are valuable or beloved pets. Most vets won’t treat poultry, only ‘pet’ birds like parrots. Preventing reexposure to the mold will increase the chances of survival.
To reduce the severity of the outbreak and the worsening of already infected birds, remove all birds from the area to a new clean living space. Clean the old area of any bedding and thoroughly disinfect feeders and waterers with something that kills spores. Cleaners that specifically kill mold spores can be found online and in some stores, search or ask for a fungicidal disinfectant safe for animals.
While cleaning a contaminated area, take care not to create clouds of dust. Move any animals from the area including dogs and other pets. Wear a mold respirator or mask while handling infective materials. Since it is possible for people to get this disease, precautions need to be taken to prevent human infection. If symptoms occur in any humans exposed, get medical attention.
If an outbreak happens with a batch of chicks, the brood will have to be moved to an entirely new area and given supportive care to minimize losses. Incubators are a huge source of mold spores when they haven’t been cleaned appropriately between hatches. In addition to clean incubating and hatching equipment, good husbandry is key.
Some hatcheries and owners choose to wash their eggs prior to incubation. This is optional, but ensure that eggs are otherwise clean and damage-free before incubating them. Eggs can become contaminated and burst into the incubator, spreading a multitude of organisms and pathogens into the hatching space.
For maintenance practices, rotate water and food dishes frequently to allow the ground to dry out and stay clean. Develop a cleaning schedule for the coops and equipment and sanitize incubators between hatches. Never feed birds moldy, wet, or otherwise contaminated feed. Uneaten food should be disposed of. If storing chicken feed, do so in a dry area that is protected from rodents and the elements.
Like many diseases, aspergillosis can be mostly prevented through good practices and biosecurity. If you think you might have an outbreak, good luck and reach out for help if needed through BYP’s Ask The Expert.
Originally published in the December 2020/January 2021 issue of Backyard Poultry and regularly vetted for accuracy.