Chicken aspergillosis, also called brooder pneumonia, is a fungal disease most often affecting the respiratory system. Young birds can become seriously ill after inhaling large numbers of airborne Aspergillus spores from contaminated hatcheries, litter, feed, dust or equipment.
Aspergillosis is not normally transmitted from one bird to another. The urgent task is to find and remove the environmental source, reduce further spore exposure and confirm the diagnosis.
What is aspergillosis in poultry?
Aspergillosis is caused by moulds in the genus Aspergillus. Aspergillus fumigatus is a common cause, but A. flavus, A. niger and other species may also be involved.
Infection begins when a susceptible bird inhales spores. In young, stressed or immunocompromised birds—or when spore concentrations are high—the spores can lodge in the respiratory system, germinate and form fungal hyphae. Granulomas may develop in the lungs and air sacs. The fungus can sometimes invade other organs, including the brain.
Healthy adult birds exposed to small numbers of spores usually do not develop disease. Risk rises with heavy contamination, poor ventilation, wet organic material, dust and reduced immunity.
Where do dangerous mould spores come from?
Aspergillus moulds are common in the environment. A disease outbreak usually reflects heavy exposure rather than spread between sick birds. Important sources include:
- wet litter or shavings that later dry and release spores when disturbed;
- mouldy feed or feed ingredients;
- contaminated hatchers, incubators or chick boxes;
- cracked or visibly contaminated hatching eggs;
- dusty, poorly ventilated housing;
- dirty ventilation fans, feeders or drinkers; and
- organic material trapped in equipment or building surfaces.
Wet bedding can support mould growth. When it dries and is swept, turned or removed carelessly, large numbers of spores may become airborne.
Does aspergillosis spread between chickens?
No. MSD states that aspergillosis is not transmissible between birds. Several birds may become ill at the same time because they shared the same contaminated air, litter, feed, hatchery or equipment.
Separating visibly ill birds can make observation and supportive management easier, but isolation alone will not stop an outbreak. The environmental source must be identified and controlled.
Symptoms of aspergillosis in chickens
The respiratory form may cause:
- gasping or open-mouth breathing;
- laboured or rapid breathing;
- neck extension while trying to breathe;
- reduced appetite;
- poor growth and unthriftiness;
- weakness and depression;
- increasing chick mortality; and
- few or no respiratory rattles in some affected birds.
Less common neurological disease may cause tremors, twisted neck or incoordination. Eye lesions and infection of other organs can also occur.
These signs are not specific. Newcastle disease, infectious bronchitis, infectious laryngotracheitis, colibacillosis and other fungal or respiratory diseases may look similar. Seek urgent veterinary or animal-health guidance when respiratory signs spread rapidly, mortality rises or a notifiable disease is possible.
How aspergillosis is diagnosed
A reliable diagnosis may combine:
- flock age, housing, hatchery and feed history;
- the timing and pattern of illness and mortality;
- postmortem identification of characteristic white, yellow or greenish granulomas in respiratory tissues;
- fungal culture;
- cytology; and
- histological demonstration of fungal hyphae invading affected tissue.
Because Aspergillus is common in the environment, merely finding mould in litter or growing it from a surface does not prove that it caused the birds’ disease. Tissue lesions and evidence of fungal invasion provide stronger confirmation.
Infographic: respond to suspected aspergillosis
Look for affected age groups, recent hatchery arrival, wet litter, mouldy feed, dust or ventilation problems.
Move birds to clean air when practical. Remove contaminated material without creating a dust cloud.
Record mortality and arrange postmortem examination, fungal culture or histology.
Repair moisture and ventilation problems, clean the hatchery or house and prevent contaminated feed or litter reaching the next flock.
Immediate flock response
- Contact a poultry veterinarian or diagnostic laboratory.
- Find and stop the likely source of mould exposure.
- Move birds to clean, well-ventilated accommodation when practical.
- Remove visibly mouldy feed and prevent access to contaminated supplies.
- Do not sweep, blow or aggressively disturb dry contaminated material around birds.
- Improve air exchange unless the ventilation system itself is contaminated.
- Provide clean water, suitable complete feed and an appropriate temperature.
- Record daily mortality, feed intake, water intake and affected age groups.
- Submit fresh dead or clinically affected birds as directed for diagnosis.
Workers handling mouldy material should follow occupational-safety guidance and use appropriate protective equipment. People with respiratory disease or impaired immunity should avoid heavy mould exposure.
Treatment and prognosis
There is no reliably effective flock treatment for poultry aspergillosis. MSD describes treatment in affected poultry as generally ineffective. Spontaneous recovery can occur when further fungal exposure stops, but severely affected birds and birds with extensive granulomas may die or remain undersized.
Do not treat a commercial or backyard flock blindly with antifungals, copper sulphate, iodine, antibiotics or “immune boosters.” Product legality, effectiveness, toxicity and food-residue rules differ, and antibiotics do not act against fungi.
Individual high-value birds may sometimes receive prolonged antifungal therapy under an avian veterinarian, but this is different from treating a poultry flock through feed or water. Diagnosis and professional oversight are essential.
A humid environment should not be recommended routinely. Excess environmental moisture supports mould growth and can worsen the source problem. Provide appropriate ventilation and temperature without chilling or stressing the birds.
Preventing brooder pneumonia
Hatchery and incubation control
- Do not set cracked, dirty or grossly contaminated eggs.
- Clean and disinfect incubators, hatchers, trays and chick boxes between batches.
- Control condensation and remove organic debris.
- Investigate respiratory disease beginning soon after hatch as a possible hatchery-source problem.
Feed and litter control
- Store feed in a dry, protected and well-ventilated place.
- Reject feed with visible mould, caking, heating or an abnormal odour.
- Use clean, dry litter from a reliable source.
- Repair drinker leaks and roof or plumbing problems quickly.
- Do not allow wet bedding to remain, dry and become heavily dusted with spores.
Housing and ventilation
- Maintain sufficient air exchange without creating harmful drafts.
- Clean fans, ducts, inlets, feeders and drinkers between flocks.
- Reduce dust while avoiding practices that aerosolise contaminated litter.
- Prevent overcrowding and other stresses that reduce resistance.
Video: practical poultry biosecurity
This USDA video covers general biosecurity practices that help prevent disease entering or moving around a poultry operation. Aspergillosis is environmentally acquired, so mould, moisture, feed, litter and ventilation control remain essential.
Frequently asked questions
Can one infected chicken spread aspergillosis to the flock?
No. Birds become infected by inhaling spores from a shared contaminated environment. Several birds can fall ill from the same source.
Can chickens recover from aspergillosis?
Some birds may recover after exposure stops, but flock treatment is generally ineffective and severe disease has a poor prognosis. Survivors may remain smaller than normal.
Should mouldy litter be removed immediately?
Yes, but avoid disturbing it in a way that creates a cloud of spores around birds or workers. Move birds first when practical and follow safe removal procedures.
Do antibiotics treat aspergillosis?
No. Aspergillosis is fungal. Antibiotics act against susceptible bacteria, not Aspergillus.
Sources and further reading
- MSD Veterinary Manual: Aspergillosis in Poultry
- Merck Veterinary Manual: Common Infectious Diseases in Backyard Poultry
- University of Florida IFAS Extension: Common Poultry Diseases
- Cornell Wildlife Health Lab: Aspergillosis
Aspergillosis control starts with the environment. Stop exposure, confirm the diagnosis and correct the hatchery, feed, litter, moisture or ventilation problem before the next flock is placed.
