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Histoplasmosis is an infectious, but non-contagious fungal disease caused by Histoplasma capsulatum. It affects a wide variety of wild and domestic animals, and occasionally reported in poultry. H. capsulatum is a dimorphic fungus which occurs naturally in soil in warm, humid regions worldwide. The organism thrives in soil mixed with accumulation of feces, especially from birds and bats.

Chickens become infected by inhaling dust containing H. capsulatum spores. In many cases, birds are concurrently infected with other fungi, usually Aspergillus spp. and have recently undergone some sort of stressful event. Stress predisposes birds to developing fungal infections.

Clinical Signs

Weight loss
Chronic respiratory signs
Loss of appetite


  • History
  • Clinical signs
  • Physical exam
  • Radiography
  • Lab tests


Amphotericin B1 mg/kg administered IT TID + 1.5 mg/kg IVK Marx
Supportive care



  • Decrease exposure to soil mixed with accumulation of feces from birds or bats.
  • Spraying infected soil and feces with 3% formalin destroys some spores.
  • Do not overcrowd or stress birds
  • Execute good management practices

Scientific References

Risk Factors

  • Birds living in warm, humid regions
  • Poor sanitary practices, allowing accumulation of feces in soil.
  • Presence of bats
  • Overcrowding
  • Recent stressful event (introduction to a new flock of birds, excessive bullying or fighting among flock members, exposure to extreme heat or cold, poor living conditions, overcrowded conditions, lack of resources such as feed or water, rough handling, predator attack or predator stalking, recent injury or sickness, etc.)