Cutaneous pythiosis in a nestling white-faced ibis.
Authors: Pesavento P A, Barr B, Riggs S M, Eigenheer A L, Pamma R, Walker R L
Journal: Veterinary pathology
Summary
# Editorial Summary: Cutaneous Pythiosis in Birds — Emerging Concern for Equine Environments Pythium insidiosum, an oomycete pathogen traditionally associated with tropical and subtropical regions, has emerged as an increasingly important cause of cutaneous and systemic disease in horses and dogs across California's central valley, yet its significance in avian species remained undocumented until this 2008 case report. A nestling white-faced ibis presenting with multifocal skin ulcerations across the wings, neck, head and limbs underwent pathological examination, microbiological culture, and molecular analysis, which collectively confirmed restricted cutaneous pythiosis—a finding unprecedented in the published literature for birds. The histopathological features mirrored those observed in mammalian pythiosis, characterised by intense necrotising eosinophilic and granulomatous inflammation that creates a distinctive microscopic pattern. The persistence of this water-mould in California's arid central valley, likely facilitated by agricultural irrigation systems and communal watering facilities, suggests environmental niches that support year-round survival despite unfavourable climatic conditions. For equine professionals, this report reinforces the importance of recognising pythiosis as an emerging endemic threat in non-tropical regions, particularly in agricultural settings with shared water sources, and underscores the potential for cross-species transmission risk when horses access contaminated water shared with diverse wildlife populations.
Read the full abstract on PubMed
Practical Takeaways
- •Equine practitioners in California should consider pythiosis in differential diagnosis for cutaneous ulcerations, particularly in horses with water exposure
- •Geographic range of pythiosis is expanding beyond traditional tropical/subtropical zones; clinical vigilance needed in agricultural regions with irrigation practices
- •This case suggests Pythium insidiosum can infect multiple species; cross-species transmission or shared environmental exposure warrants investigation
Key Findings
- •First documented case of pythiosis in avian species (white-faced ibis nestling)
- •Pythium insidiosum caused multifocal necrotizing and granulomatous inflammation on wings, neck, head, and limbs
- •Pythiosis has emerged in California in both horses (cutaneous) and dogs (enteric) despite arid climate
- •Agricultural and community watering practices may facilitate environmental persistence of Pythium in non-tropical regions