Aspergillosis in Chickens: Symptoms, Causes and Treatment

Aspergillus fumigatus produces millions of spores (conidia) per gram of infected substrate. Inhalation of high spore loads overwhelms respiratory defenses in young or immunosuppressed birds.

• Moldy hatchery equipment: Incubator or hatcher contamination with Aspergillus exposes all chicks to massive spore loads at hatch. This is the most common cause of brooder pneumonia outbreaks affecting large numbers of chicks simultaneously.
• Contaminated bedding: Wood shavings, straw, or peat moss that has been stored in damp conditions can harbor active Aspergillus growth. Disturbing moldy litter releases spore clouds that chicks inhale.
• Moldy feed: Improperly stored feed, especially corn-based diets, supports Aspergillus growth. Feed should be stored in sealed, dry containers and used within 2-3 weeks of manufacture.
• Immunosuppression: Adult birds rarely develop aspergillosis unless immunosuppressed by IBD, CIA, corticosteroids, or chronic stress. A sporadic adult case always warrants investigation for an underlying immunosuppressive condition.

Brooder pneumonia in a group of young chicks with recent exposure to new bedding or a hatchery is presumptively diagnosed on clinical signs and history.

• Flock pattern: Multiple chicks gasping within the first 2 weeks of life, especially if the problem began shortly after placement on new bedding or arrival from a hatchery.
• Necropsy: Classic findings are grayish-white to yellowish plaques (granulomas) in the lungs and air sacs. Advanced cases show plaques in the trachea, syrinx, and brain. The organism can sometimes be seen as blue-green mold growth within lesions.
• Fungal culture: Minced lung tissue plated on Sabouraud's dextrose agar grows Aspergillus colonies within 48-72 hours. PCR is more sensitive and faster.
• Differentials: IB (respiratory but spreads rapidly to whole flock), Marek's (neurological in older birds), heat stress (behavioral without lung lesions), nutritional deficiency.

Treatment of aspergillosis in poultry is generally unrewarding. Antifungal drugs are expensive, require extended courses, and do not reverse established granulomatous lesions in the lungs.

Itraconazole: 5-10 mg/kg orally once daily for 21-45 days has some efficacy in early cases or high-value individual birds. Not practical for large flock outbreaks. Requires compounding for poultry use.

Amphotericin B: Nebulization (via aerosol therapy) at 1 mg/mL for 15-30 minutes twice daily for 5-7 days has been used in individual pet birds. Not practical for production flocks.

Copper sulfate in water: 1:2000 dilution has some antifungal properties and has been used as a flock-wide adjunct. Not a replacement for removal of the spore source.

Most important intervention: Remove and replace all contaminated bedding and feed immediately. Eliminate the spore source. Improved ventilation dilutes remaining spore load. For hatchery-associated outbreaks, professional disinfection of incubators and hatchers with formaldehyde fumigation or other approved antifungal disinfectants is essential.

• Never use visibly moldy bedding, straw, or feed. Inspect all bedding materials before placement. Aspergillus grows on damp wood shavings, straw, peat, and any organic material stored in humid conditions.
• Store feed in sealed, dry containers away from moisture. Feed stored in paper bags in humid environments can support Aspergillus growth within 1-2 weeks.
• Disinfect incubators and hatchers between every hatch with formaldehyde fumigation or other approved antifungal agents. Hatchery aspergillosis infects all chicks simultaneously and can cause catastrophic losses.
• Maintain adequate ventilation in brooder areas. High humidity and ammonia both predispose respiratory tracts to fungal colonization.
• Change litter promptly if it becomes wet. Wet spots around drinkers are a primary Aspergillus growth site in brooder houses.