Why does using damp, moldy litter (sawdust or rice husks) trigger high mortality from Aspergillosis in day-old brown chicks?

Aspergillosis, commonly known as "Brooder Pneumonia," is a highly fatal fungal disease of young chicks caused by the inhalation of microscopic spores of the fungus Aspergillus fumigatus. If a farm uses sawdust or rice husks that have been stored under damp, humid conditions, the fungus replicates rapidly, releasing billions of microscopic, lightweight conidia (spores) into the air. When day-old chicks are placed on this moldy litter, their rapid respiratory rate draws these spores deep into their non-expansible lungs and extensive air sac system. The warm, moist respiratory environment triggers the spores to germinate, growing fungal hyphae that physically penetrate and destroy the lung tissue and air sac walls. Chicks present with severe respiratory gasping, silent chirping, and high mortality within the first 5 days. There is no veterinary cure; prevention requires strict litter dry-storage and pre-treatment with anti-fungal agents. Farmers can read fungal pathology in the Poultry Encyclopedia, buy litter disinfectants and dry sawdust on Poultry Plaza, check daily chick prices on Poultry Rates, and trade healthy batches on Murghi Mandi.