Candidiasis (Candida albicans)
Introduction
Candidiasis is an opportunistic fungal infection caused mainly by Candida albicans. It is a commensal organism of mucosal surfaces but can become pathogenic under conditions that disrupt normal flora or compromise immunity. The disease commonly affects mucous membranes, skin, and occasionally internal organs in animals.
Etiology
Causative Agent
- Candida albicans (most important species)
- Other species: Candida tropicalis, Candida parapsilosis (less common in animals)
Organism Characteristics
- Yeast-like fungus (dimorphic nature: yeast and pseudohyphae)
- Part of normal flora in gastrointestinal and urogenital tracts
- Opportunistic pathogen
- Forms biofilms on mucosal surfaces and medical devices
Epidemiology
Species Affected
- Poultry (especially chicks and poults)
- Cattle (rumen and abomasal involvement in young animals)
- Dogs and cats (mucocutaneous infections)
- Horses (gastrointestinal or reproductive tract infections)
Transmission
- Endogenous overgrowth of normal flora
- Contaminated feed or water (less common)
- Fomites in clinical settings (medical devices, catheters)
Risk Factors
- Antibiotic therapy (disruption of normal microbial flora)
- Immunosuppression
- Stress and poor nutrition
- Moist environments (skin and mucosal irritation)
Pathogenesis
Overgrowth of Yeast
Disruption of normal flora allows Candida to proliferate excessively.
Adherence and Invasion
- Adheres to epithelial surfaces
- Forms pseudohyphae that invade superficial tissues
Inflammatory Response
- Localized inflammation of mucosa or skin
- Exudation and tissue necrosis in severe cases
Clinical Signs
Gastrointestinal Candidiasis
- Diarrhea (especially in young animals)
- Oral lesions (white plaques)
- Poor growth and weight loss
Cutaneous Candidiasis
- Moist dermatitis
- Erythema and itching
- Lesions in skin folds
Systemic Infection (Rare)
- Fever
- Lethargy
- Multi-organ involvement in severely immunocompromised animals
Summary for Practitioners
Candidiasis should be suspected in animals with mucosal or skin lesions following prolonged antibiotic therapy or immunosuppression.
Diagnosis
Clinical Diagnosis
Based on history (antibiotic use, immunosuppression) and characteristic mucosal lesions.
Laboratory Diagnosis
- Microscopic examination (budding yeast and pseudohyphae)
- Culture on Sabouraud dextrose agar
- Cytology from lesions
Differential Diagnosis
- Dermatophytosis (ringworm)
- Bacterial dermatitis
- Other opportunistic fungal infections
Treatment
Antifungal Therapy
- Nystatin (topical or oral for mucosal infections)
- Fluconazole
- Itraconazole (systemic cases)
Supportive Management
- Correction of underlying causes (stop unnecessary antibiotics)
- Nutritional support
- Skin hygiene and drying of affected areas
Control and Prevention
Management Practices
- Avoid prolonged antibiotic use where unnecessary
- Maintain good hygiene in animal housing
Biosecurity
- Proper sterilization of medical equipment
- Reduce environmental moisture in housing
Summary
Candidiasis is an opportunistic fungal infection caused mainly by Candida albicans, associated with mucosal and cutaneous disease in animals with disrupted normal flora or compromised immunity.
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