Outbreak of equine pythiosis in a southeastern region of Brazil: Environmental isolation and phylogeny

Abstract

Pythiosis is a disease caused by the oomycete Pythium insidiosum, mainly reported in equines, dogs and humans and directly transmitted through contaminant zoospores in aquatic environments. We report the first outbreak of equine pythiosis in five equines. Wound samples were submitted for diagnostic testing including mycological culture and nested PCR. Treatment approaches consisted of conventional and alternative therapies. Microbiological analyses were performed using water samples from the riverbanks close to where the animals had grazed. All animals were positive for P. insidiosum cultures, and two animals responded successfully to alternative therapy (ozone therapy). After culture and molecular analysis of environmental samples, the presence of P. insidiosum in one section of the Tietê River was confirmed through a 99% sequence identity. Phylogenetic analyses using the cytochrome oxidase II gene showed that the animal isolates clustered in clade I and the environmental isolates clustered in clade III. Although the environmental and wound isolates belonged to different genetic clades, we concluded that the Tietê River is an important source of infection by P. insidiosum and that research concerning environmental isolation of P. insidiosum from rivers and lakes should be strongly facilitated in Brazil.

Inmunoterapia y manejo quirúrgico de Pythium insidiosum en un equino: reporte de caso

“…La mayoria de los casos reportados en equinos son en Sudamérica (Salas et al, 201, Cardona et al, 2014, Dória et al, 2015, Schanzembach et al, 2019, Paz et al, 2021, lo cual se relaciona con sus regiones tropiales y subtropicales. El estado de Veracruz presenta condiciones ambientales similares, por ejemplo, abundantes lluvias que favorecen el estancamiento de agua en las praderas y temperaturas elevadas, que benefician al agente etiológico y su contacto con los equinos (Gaastra et al, 2010).…”

Hyphae, pseudohyphae, yeasts, spherules, spores, and more: A review on the morphology and pathology of fungal and oomycete infections in the skin of domestic animals

“…31 Pythiosis and lagenidiosis, collectively known as oomycosis, are emerging diseases of temperate, tropical, and subtropical climates caused by the globally distributed oomycetes Pythium and Lagenidium , respectively. 31,76 These fungal-like eukaryotic microorganisms belong to the Kingdom Stramenopila and are phylogenetically more closely related to algae than fungi. They possess cellulose and β-glucan rather than chitin or ergosterol as the primary component of the cell wall or membrane, respectively.…”