Aspergillosis in Chickens Notes

History

  • In 1729, Italian biologist and priest Pier Antonio Micheli published the first description of the fungus Aspergillus.
  • In 1856, Rudolf Virchow detected fungal infections in the lungs and described the first human instance of aspergillosis.
  • Aspergillosis is a disease known to afflict birds and cattle, especially poultry, and has raised financial problems in farming.
  • The 20th century saw the development of antifungal treatments.

What is Aspergillosis?

  • Aspergillosis is a fungal respiratory disease caused by an aspergillus spore.
  • The infection occurs by the inhalation of conidia (spore). It mainly affects hatchlings more than adult birds.
  • This specific fungus is commonly found in environments such as soil, feed, and dust.
  • It can grow in a chicken's respiratory tract, leading to inflammation and tissue scarring.
  • Also known as Brood Pneumonia.
  • It can affect various poultry species, including turkeys, ducks, and quail.

Clinical Signs and Diagnostics

  • Common Clinical Signs:
    • Respiratory Symptoms (Dyspnea/Gasping/Labored breathing)
    • Emaciation/ Inappetance/Stunting
    • Fever
    • Increased Mortality/Death
    • Necropsy: Yellowish white nodules in lower airway and lung lobes
  • Uncommon Clinical Signs:
    • Neurological symptoms (Torticollis/Tremors/ Incoordination)
    • Ocular opacity
  • Diagnostics-Laboratory Test
    • Direct Microscopy
      • Staining (Lactophenol cotton blue, GMS) reveals fungal hyphae.
      • Granulomatous inflammation with fungal hyphae.
    • Fungal culture
      • Grows on Sabouraud dextrose agar, producing greenish colonies.
    • Histopathology
    • Molecular test
      • PCR and ELISA detect fungal DNA or antibodies.

Transmission: How it is Spread

  • Primary cause of infection: Inhalation of spores
    • Young chicks and immunocompromised are more vulnerable
    • Overcrowding can be an increased risk factor
    • Poor husbandry practices/ unclean environments are related to outbreaks

Zoonotic Considerations

  • Birds to Human: Cannot be transmitted from birds to humans, but humans can become infected by inhaling spores when working with contaminated materials
  • Risks to Human: People with weakened immune systems or lung disease are at higher risk of developing health problems from Aspergillus Spores

Treatments

  • Treatment Options:
    • Typically treatments are an extensive process
    • Antifungal Treatment Methods Include:
      • Orally
      • Topical application using endoscopy
      • Nebulization with antifungal agents
    • Supportive Care:
      • Isolation from the flock in a warm location to limit stress and help with breathing
      • Contact a vet
      • The removal of old fungus from the coops to improve ventilation
  • Most common Antifungals used for treatments
    • Amphotericin B
      • Can be IV Administered, used in the form of a lotion or in the form of a sinus flush
    • Voriconazole
      • Second line of treatment
      • Less threatening side effects
    • Itraconazole
      • Taken Orally
      • First Line of treatment for invasive aspergillosis
      • Administered through Iv or Orally

Prevention

  • Since this disease is known for loving damp and moldy environments, there are different ways to keep it under control:

    • Maintain a dry and clean coop
    • Make sure there is proper ventilation
    • Avoid overcrowding
    • Store feed properly

  • Wood vs Wire

    • Wood chicken coop-
      • High Mold risk
      • Limited ventilation
      • Harder to clean
      • High maintenance
    • Wire chicken coop-
      • Low mold risk
      • Open ventilation
      • Resistant to mold
      • Can be hosed down

Effects on the Industry

  • Market loss
    • Aspergillosis causes a lot of feed and bedding to be removed because of how fast the spores spread.
    • Aspergillosis drastically affects the market negatively due to the high mortality rates and reduced productivity rates.
  • Hatcheries
    • The hatcheries are the main ones affected due to how many chicks are lost, which affects the trade flow of the poultry industry.
  • Animal welfare

Fact Or Myth?!

  1. Aspergillosis is contagious between birds. (Myth)
  2. Keeping poultry bedding dry can help prevent aspergillosis. (Fact)
  3. There is no effective treatment for aspergillosis in poultry. (Myth)