Pythiosis in Equidae in Northeastern Brazil: 1985-2020.
Authors: Souto Erick Platiní F, Maia Lisanka A, Neto Eldine G Miranda, Kommers Glaucia D, Junior Felício Garino, Riet-Correa Franklin, Galiza Glauco J N, Dantas Antonio F M
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Pythiosis in Equidae in Northeastern Brazil Over a 36-year period (1985–2020), researchers at the Federal University of Campina Grande examined 1,331 equine tissue samples and identified pythiosis in 202 cases (15.17%), establishing it as an endemic concern in northeastern Brazil with marked seasonality, peaking at 70% incidence following the rainy season. The disease affected horses and donkeys across all ages and both sexes, predominantly in extensively managed, mixed-breed animals, presenting as a chronic condition characterised by nodular or tumorous limb and ventral thoracoabdominal lesions containing fistulous tracts with distinctive kunkers (intralesional fungal aggregates). Histopathological examination revealed marked eosinophilic inflammation with multifocal necrosis and collagenolysis, whilst immunohistochemistry using anti-*Pythium insidiosum* antibodies provided definitive confirmation of the pathogen. Although the presence of kunkers within draining lesions permits presumptive diagnosis in the field, the authors emphasise that confirmation requires histopathology combined with immunohistochemistry, culture, or molecular testing—a protocol particularly valuable given the destructive nature of this chronic infection and the importance of differentiating pythiosis from other granulomatous conditions. For equine professionals in endemic regions, understanding the seasonal risk window and the diagnostic utility of kunkers combined with histological examination should inform both clinical investigation strategies and client education regarding environmental risk factors associated with waterlogged pastures.
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Practical Takeaways
- •Pythiosis is endemic in northeastern Brazil; suspect this disease in equidae with chronic nodular/ulcerative lesions on limbs and ventral body wall, especially after rainy seasons
- •Finding kunkers (organized hyphal masses) on direct examination strongly suggests pythiosis and warrants immediate referral for histopathology and immunohistochemistry to confirm before treatment
- •Disease management should account for the chronic nature and seasonal peaks; implement environmental management to reduce exposure during and after wet seasons in endemic regions
Key Findings
- •Pythiosis accounted for 15.17% (202/1,331) of equine tissue samples submitted to the laboratory over 36 years
- •70.29% of cases occurred in the post-rainy season, indicating strong seasonal epidemiologic variation
- •Lesions were predominantly located on limbs and ventral thoracoabdominal wall and always presented with a chronic clinical course
- •Intralesional kunkers containing sparsely septate hyaline hyphae are pathognomonic; confirmation requires histopathology with immunohistochemistry or culture