Equine pythiosis in Egypt: clinicopathological findings, detection, identification and genotyping of Pythium insidiosum

Abstract

BackgroundEquine pythiosis is an emerging, devastating disease that is hard to treat. The tumour‐like nodular skin masses grow rapidly and the outcome is generally fatal, and thus early diagnosis and intervention are important.Objectives(i) To highlight the clinical, histological and haematological findings in pythiosis, and (ii) to evaluate the efficacy of direct sample multiplex‐PCR targeting the single nucleotide polymorphisms within the ribosomal DNA region for detection and genotyping of Pythium insidiosum.AnimalsTwo hundred and twenty horses including 204 Arabian and 16 draft horses were surveyed.MethodsCase series study diagnosis was based on clinical, pathological and haematological findings typical of P. insidiosum infection, culture identification, immunohistochemical investigation and direct sample PCR.ResultsThe affected horses (24 of 220, 10.91%) presented with unifocal or multiple lesions on the abdomen, limbs, chest, face and mammary gland. Cases commonly had a history of access to stagnant water, ponds and intentionally flooded rice fields. Most were pregnant mares (58.33%). Histopathology revealed granulomatous reaction, blood vessel endotheliosis, heavy infiltration of eosinophils in the dermal layer, multifocal necrosis and Splendore–Hoeppli phenomenon. Unlike direct microscopy (50%) and culture (91.6%), multiplex‐PCR assay identified P. insidiosum (Clade II) in all tested samples. To the best of the authors knowledge, this is the first study determining a clade of P. insidiosum causing equine pythiosis in Egypt.Conclusions and clinical importanceDirect sample multiplex‐PCR assay is a potential tool for the early and rapid diagnosis of equine pythiosis. It overcomes limitations associated with morphological identification and provides a definitive diagnosis.

Nucleic Acid-Based Detection of Pythium insidiosum: A Systematic Review

“…The m-PCR assay exhibited 100% detection sensitivity and specificity based on the performance assessment against 53 P. insidiosum isolates and 22 control fungi. The SNP-based m-PCR assay has been used to identify and genotype P. insidiosum isolated from affected animals (primarily horses and dogs) in South America [ 26 ] and Egypt [ 25 ], as well as in the environment in Thailand [ 27 ]. Recently, Kulandai et al [ 35 ] described a duplex-PCR (d-PCR) assay for simultaneously detecting the 18S rRNA (using the primers Pin1 and Pin2) and ITS (using the primers ITSpy1 and ITSpy2 [ 36 ]) sequences of P. insidiosum in corneal specimens from patients with suspected ocular pythiosis.…”

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

“…Las lesiones cutáneas encontradas en la region periorbital de la yegua concuerdan con la descripcion de las lesiones cutáneas granulomatosas descritas en otros informes de caso en diferentes países (Bezerra-Junior et al, 2010, Mosbah et al, 2012, Cardona et al, 2014, Tartor et al, 2020, en donde se reportan lesiones cutáneas en regiones anatómicas que se encuentran en contacto directo con aguas estancadas contaminadas con zoosporas de P. insidiosum, por lo que las lesiones en regiones altas de la cabeza no son comunes. Sin embargo, en Tailandia se notificó el primer caso con lesiones de pitiosis dentro de la cavidad nasal de una yegua gestante y anticuerpos para P. insidisum en tres caballos (Tonpitak et al, 2018, Mar Htun et al, 2021.…”

Global Distribution and Clinical Features of Pythiosis in Humans and Animals

“…Animals with pythiosis predominantly manifested with a cutaneous/subcutaneous infection at the face, limb, thorax, or abdomen (n = 3082; 89.8% of all affected animals; Table 3) [138][139][140][141][142][143][144][145][146][147][148][149]. To a much lesser extent, some affected animals (n = 350; 10.2%) came with clinical manifestations associated with gastrointestinal (n = 249; 7.3%), disseminated (n = 25; 0.7%), pulmonary (n = 4; 0.1%), or other organ (n = 5; 0.1%) infection (Table 3).…”