tlP7wE-avian fungal diseases

Avian Fungal Diseases

Avian Mycoses

• Common in pet birds.

• Pathogens in the environment are usually non-dangerous for healthy birds but can cause chronic diseases in immunocompromised ones.

• Types of mycoses include:

  • Respiratory aspergillosis

  • Candidiasis (digestive system)

  • Macrorabdiosis (megabacteriosis)

• Challenges in diagnosis and treatment exist, but advancements in diagnostic methods and antifungals can reduce morbidity and mortality.

Aspergillosis

Overview

• Non-infectious, opportunistic fungal disease caused by Aspergillus spp. (approx. 600 species).

• Symptoms depend on the affected organs and infection type (localized/systemic).

• Most common in the respiratory system; can affect eyes, brain, skin, joints, and abdominal cavity.

Common Species

• Frequently seen species: A. fumigatus, A. flavus, A. niger, A. terreus.

• Optimal growth in high humidity and at 25°C, commonly found in wet litter and contaminated environments.

• Birds can carry spores asymptomatically until immunosuppression occurs.

Pathogenesis

• Predisposing Factors:

  • Stress

  • Poor housing and feeding

  • Previous illnesses

  • Long-term use of antibiotics/corticosteroids

• Respiratory form prevalent in overcrowded and dusty aviaries.

• Acute form arises from inhaling large spore quantities, especially in seed-eating birds with vitamin A deficiency.

Commonly Affected Bird Species

• African grey parrots, Pionus spp., birds of prey, penguins.

• Infection occurs aerogenously or via food; can spread through air sacs to other body parts.

Clinical Signs - Acute Form

• Fatal respiratory disease common in young or newly acquired birds with immunosuppression.

• Rapid onset, death within days; symptoms include:

  • Dyspnea

  • Cyanosis

  • Anorexia

  • Polyuria and polydipsia

• Necropsy findings:

  • White mucous exudate in air sacs

  • Lung congestion

  • Possible ascites and vomiting.

Clinical Signs - Chronic Form

• More common in older birds with prolonged captivity.

• Nonspecific signs:

  • Behavioral changes

  • Decreased activity

  • Poor appetite

  • Weight loss

• Possible findings:

  • Biliverdinuria

  • Hepatomegaly

  • Inflammation of air sacs and granulomas in lungs.

Diagnosis

• Preliminary diagnosis based on clinical signs, examination, blood count, X-rays.

• Definitive diagnosis via mycological examination, endoscopy, PCR, and necropsy.

Treatment

• Treatment can be local or systemic.

  • Systemic:

    • Ketoconazole (caution with dosage)

    • Itraconazole (not for AGP)

    • Fluconazole

    • Voriconazole (best option)

• Inhalations with Enilconazole.

Candidiasis (Thrush, Moniliasis)

• Involves fungal infections of the digestive system caused by Candida species, especially C. albicans.

Pathogenesis of Candidiasis

• C. albicans is opportunistic; normal flora in pigeons.

• Proliferates due to:

  • Stress

  • Immunosuppression

  • Poor housing

  • Long-term antibiotics.

Clinical Signs of Candidiasis

• Affects gastrointestinal mucosa (oropharynx, crop, esophagus).

• Symptoms include:

  • Depression

  • Delayed crop emptying

  • Regurgitation

  • Poor digestion

• Feces appear brown, semi-aqueous with sour smell.

Diagnosis

• Isolation of Candida via mycological examination.

• Differential diagnoses include bacterial stomatitis, trichomoniasis, dietary errors.

Treatment of Candidiasis

• Improve housing conditions/diet.

• Nystatin commonly used (oral/topical); dose 100,000 IU/kg every 12-24 hours.

• Chlorhexidine may treat flocks via drinking water.

Megabacteriosis

• Common in budgerigars, canaries, cockatiels, and less in larger parrots.

• Caused by Macrorhabdus ornithogaster, a large rod-shaped microorganism.

Clinical Signs of Megabacteriosis

• Signs: apathy, anorexia, bristly feathers, occasional vomiting, black-brown watery diarrhea, significant weight loss.

• Common in young (10 days to months) and may present with secondary infections.

Diagnosis of Megabacteriosis

• Life birds: stained microscopic preparation from feces/crop.

• Postmortem: smear from glandular stomach.

Treatment of Megabacteriosis

• Ineffective antibiotics; antifungal treatments include nystatin, fluconazole, and amphotericin B.

• Considerations for water acidification and the use of probiotics.