Aspergillosis: The Mould Disease
TL;DR: Aspergillosis is a fungal disease breathed in from mouldy bedding, feed or hatchery material — not caught from other birds. That single fact changes everything: an outbreak is a housing problem, not a flock problem, and isolating birds achieves nothing while the source is still there. It hits chicks in brooders hardest, where it is called brooder pneumonia. Treatment is difficult and often unsuccessful. The whole game is prevention: dry bedding, dry feed, clean brooders and incubators.
The disease where the diagnosis tells you to go and look at your bedding.
Not Contagious
Almost every other disease on this site spreads bird to bird. This one does not.
Every affected bird inhaled spores from its environment. There is no transmission between birds, which means:
- Several birds affected at once does not indicate spread. It indicates that several birds were breathing the same contaminated air.
- Isolating sick birds does nothing unless you also deal with the source.
- The investigation is of the housing, not of the flock.
That reframing is the most useful thing in this guide. A keeper who treats an aspergillosis outbreak as an infectious one will separate birds, disinfect against bacteria, and watch it continue — because the mouldy litter is still in the house.
Where It Comes From
| Source | Typical situation |
|---|---|
| Damp bedding | The classic — litter that has taken up moisture |
| Mouldy feed | Especially oil-bearing material like darak or copra meal |
| Damp storage | Sacks on a concrete floor in the wet season |
| Dirty incubators and hatchers | A recognised route into a batch of chicks |
| Mouldy litter under a brooder | Warm, humid, enclosed — ideal conditions |
The Philippine climate does most of the work. Humidity, the wet season, and informal storage together make mould the default outcome rather than an accident — see chickens in the rainy season.
What It Looks Like
Most often in young chicks, where it is called brooder pneumonia:
- Respiratory difficulty and gasping.
- Listlessness, birds sitting apart.
- Deaths, sometimes without much warning.
- Often without the rattling and nasal discharge keepers associate with respiratory illness — which is one reason it gets misread as a bacterial problem.
See sick chick symptoms and chick mortality causes for what else presents this way, and gamot sa sisiw na matamlay.
Do not diagnose this from a list. Respiratory signs in chicks have several possible causes and some are serious and spread. What you can do is tell your vet or agrivet whether there was damp bedding, damp feed, or a recently used incubator in the picture — that history is genuinely useful to them.
Treatment
Honestly: difficult, and often unsuccessful, particularly in young birds. Fungal disease in the avian respiratory system is hard to reach and the damage is frequently advanced by the time it is recognised.
Veterinary advice is what is available. This guide names no drugs and no protocols, because the decision is a vet’s and the outcome depends on what is found.
The environmental source has to be removed regardless. No treatment holds against continued exposure.
Prevention Is the Whole Thing
Every item here is cheap, and together they are more effective than any treatment:
Bedding
- Keep it dry. Wet litter is the root of most Philippine poultry problems, this one included — see chickens in the rainy season.
- Remove wet patches the day you see them.
- Never use bedding that has been rained on or stored damp.
- Manage the drinker area, the wettest spot in any coop — see chicken waterers.
- Ventilate. Air movement removes moisture — see coop ventilation.
- If you run deep litter, that guide is already explicit that Philippine humidity works against the method.
Feed
- Sealed containers, off the floor.
- Smaller quantities more often in the wet season.
- Smell every batch. Musty means discard.
- Mouldy feed is discarded, never fed — see what not to feed chickens and corn for chicken feed on the related aflatoxin problem.
Brooders and incubators
- Clean and disinfect between batches — see cleaning and disinfecting a chicken coop.
- Dry bedding under the brooder, checked daily — see brooder box design and how to brood chicks.
- Do not run a dirty incubator. See how to incubate chicken eggs and how to store hatching eggs.
Your nose is the instrument. If the coop, the feed or the brooder smells musty, act that day.
The Honest Limits Here
That aspergillosis is caused by inhaling Aspergillus spores from contaminated bedding, feed or hatchery environments, that it does not transmit bird to bird, that young chicks are particularly susceptible, and that treatment is difficult with often poor outcomes, is established veterinary knowledge. This guide gives no treatment protocol, no drug names and no dosages — treatment is a veterinary decision and prevention is what a keeper actually controls. Respiratory signs have multiple possible causes, several serious; get a diagnosis rather than assuming. Anything mouldy is discarded rather than used.
Related: chick mortality causes, chickens in the rainy season, coop ventilation, what not to feed chickens.
Frequently Asked Questions
What is aspergillosis in poultry?
A fungal disease caused by inhaling Aspergillus spores, usually from mouldy bedding, feed or hatchery material. In young chicks it is often called brooder pneumonia.
Is aspergillosis contagious between chickens?
No. Birds do not catch it from each other. Every affected bird breathed in spores from a contaminated environment, which is why an outbreak points at the housing rather than at the flock.
What are the signs of aspergillosis?
Respiratory difficulty, gasping, listlessness and deaths, most often in young chicks. Unlike bacterial respiratory disease it typically does not produce the rattling and discharge keepers expect.
Can aspergillosis be treated?
Treatment is difficult and outcomes are often poor, particularly in young birds. Veterinary advice is needed, and the environmental source must be removed regardless.
Where does the mould come from?
Damp bedding, mouldy feed, damp storage, dirty incubators and hatchers, and litter that has taken up moisture. Humid conditions and poor storage are the underlying cause.
How do I prevent aspergillosis?
Dry bedding, dry feed stored sealed and off the floor, clean incubators and brooders, good ventilation, and discarding anything mouldy rather than using it.
Why do chicks get it more than adults?
Young chicks are more susceptible and are kept in warm, enclosed brooders where damp bedding is easy to create and spores concentrate.