Aspergillosis is a serious threat for especially young chickens. The fungus will grow in the lungs and block the inhalation of air, resulting in chicks gasping for air and dying from lack of breathing. The chicks are typically lying stretched out on the litter and one can often hear the chicks gasping for air.
We normally expect that aspergillosis is hatchery related, that it comes with the day old chicks when they arrive at the farm. Although that is often the case, it can originate from the farm as well.
The incubation time for the fungus is 2 to 5 days, which means that if the chicks inhale it in the hatcher we will see the first signs on the first or second day on the farm, and the mortality will go up and stay up often until 7 to 10 days. Hatchery contamination can occur when organic material is present (hand collected litter nests, paper trays etc) or when for instance the air ducts in the hatchery are contaminated.
When the infection is coming from the farm, it will typically show after a few days, 4 to 7 days, depending if there is a high level of fungus in the litter already, or if the spores in the litter still have to multiply into toxic levels.
Contaminated litter (for instance straw that has not been stored dry) can contain high level of fungus, but it can also occur when the floors in the house are not pre-heated properly. When the concrete of the floor is too cold, condensation on the floor will occur and the litter on top of it will get wet. This might result in fungal growth as well, and can sometimes be observed as dark or black straw or shavings when the litter layer is turned upside down.