Pythiosis In Horses Research Articles

Equidae pythiosis in Brazil and the world: a systematic review of the last 63 years (1960-2023).

This systematic review compiles reports of clinical pythiosis in horses, mules and donkeys from 1960 to 2023 worldwide, focusing on Brazil. We searched databases and included 71 articles detailing clinical characteristics, geographic distribution, epidemiology, diagnostic methods, therapies, and outcomes. The results showed that publications on equine pythiosis have significantly increased since 2010. Brazil reported the highest incidence, comprising 55% of cases, predominantly in the southern, northeastern, and central-western regions during summer and autumn. Cutaneous pythiosis was the most prevalent form, generally presenting as single lesions in the appendicular region, and affected females more than males. Diagnosis typically involved histopathology, used alone or with other methods. Various treatments have been employed, with surgery, often combined with chemotherapy and immunotherapy, being the most common. Notably, 80.84% of treated animals recovered, highlighting the effectiveness of these therapies in enhancing survival rates. The limitations of the study included the lack of data in published case reports, which made it difficult to collect and calculate epidemiological data. Additionally, we recognize that pythiosis in Brazil is underreported, since this disease does not have mandatory notification and several cases are not registered and/or reported in the literature. Lastly, it is hypothesized that equid pythiosis may be more widespread than currently known, and its real occurrence in Brazil remains uncertain.

Anti-Pythium insidiosum imunoterapia intradérmica em equinos: diagnóstico e terapia

ABSTRACT: Pythiosis is a life-threatening disease that affects various species and is prevalent in regions with high humidity. The ailment is increasingly reported globally, and in Brazil, it is an important cause of profound economic and health losses in equines. This study aimed to explore the potential of intradermal immunotherapy as both a diagnostic and therapeutic approach for pythiosis in horses from the Pantanal region of Mato Grosso, Brazil. The horses were divided into three groups: those never diagnosed with pythiosis or with lesions that could be mistaken for pythiosis (Group 1); previously infected but successfully treated horses (Group 2); and horses with a positive diagnosis for pythiosis that were under treatment (Group 3). An immunotherapeutic product (PitiumVac®) was administered intradermally. Injection site reaction and response to immunotherapy were assessed. The results indicated that intradermal immunotherapy could be a viable diagnostic and therapeutic tool, particularly in remote areas where traditional laboratory diagnosis methods are not readily accessible. The efficacy of intradermal administration was comparable to that of subcutaneous administration in treating pythiosis in horses, and the combined use of immunotherapy and triamcinolone acetonide yielded promising results for treating pythiosis in horses. However, further research is required to validate these findings. This study contributes to understanding and managing pythiosis more efficiently by providing a simple, cost-effective, and potentially efficient alternative approach to diagnosis and treatment.

Epidemiology of horse pythiosis in the Pantanal of Mato Grosso: Exploring the host-parasite-vector relationship

Horse pythiosis is considered an endemic disease in the Brazilian Pantanal region, causing devastating health and economic losses. This study aimed to enhance the understanding of pythiosis epidemiology, map the distribution of horse body lesions, and investigate the correlation between these lesions and warm body surface areas, potentially implicating hematophagous vectors in the disease's transmission. A prospective study was conducted on equids in the Pantanal Mato-grossense and adjacent areas from 2012 to 2022, with 112 horses and three mules diagnosed with pythiosis. Clinical and epidemiological data, lesions' photographic records, and healthy equids' thermal imaging were collected. Most pythiosis cases occurred between January and March, correlating with regional flood cycles. Most lesions were found on limbs and the ventral abdomen, with dark-colored horses exhibiting a higher frequency of lesions. Interestingly, the thermal mapping revealed that warm areas on a healthy horse's body overlapped significantly with lesion distribution – blood-sucking insects also prefer these areas. The results suggest that pythiosis lesions in horses correlate with warmer areas of the animal body, reinforcing the hypothesis of vector involvement in disease transmission. This study underscores the need for further observational research to fully understand the complex epidemiological dynamics of pythiosis in horses.

An initial survey of 150 horses from Thailand for anti-Pythium insidiosum antibodies

IntroductionPythium insidiosum causes a life-threatening infection termed pythiosis in humans and other animals. The organism has been identified in tropical and subtropical environments worldwide. Since 1985, human pythiosis has been increasingly reported from Thailand. Seroprevalence studies estimated that 32,000 Thai people had been exposed to the pathogen. In 2018, the first animal pythiosis case in Thailand was diagnosed in a horse. Here, we investigated the seroprevalence of anti-P. insidiosum antibodies in the Thai equine population. Materials and methodsWe surveyed serum anti-P. insidiosum antibodies in 150 horses distributed across Thailand, using three established serological tests: enzyme-linked immunosorbent assay (ELISA), immunochromatographic test (ICT), and Western blot analysis. ResultsELISA detected the anti-P. insidiosum antibodies in three horses. ICT and Western blot confirmed the presence of the antibodies in one of the ELISA-positive horses. Based on one positive out of 150 horses tested, the seroprevalence of anti-P. insidiosum antibodies in the Thai equine population was 0.7%, which is markedly higher than that in the Thai human population (0.07%), but much lower than that in the Brazilian equine population (11.1%). ConclusionThe seroprevalence of the anti-P. insidiosum antibodies in the equine population suggests a higher incidence of pythiosis in horses than in humans. The antibody surveillance reported by our group was undertaken to promote a better understanding of the epidemiology and host susceptibility of pythiosis in Thailand.

Cranioesophageal Pythiosis in a Horse

Background: Pythiosis is a chronic inflammatory disease that is caused by oomycete Pythium insidiosum. This illness affects several species including humans and horses. Equine is the most affected species, having no predisposition for breed, gender, or age. It is usually shown in cutaneous and subcutaneous forms, and the lesions, which grow quickly and are hard to treat, are located mainly in the extremities. The diagnosis is made via epidemiology, clinical signs, and macroscopic and microscopic aspects of the lesion. This study describes a case of cranioesophageal pythiosis in a horse, examining the epidemiological, clinical and pathological characteristics.Case: A 12-year-old male quarter horse, weighing 515 kg was taken to the Veterinary Hospital at the University Center of Espírito Santo (UNESC). The horse had an increase in volume in the cranioesophageal region, coughing, difficulty breathing, and a runny nose. On clinical examination, the horse showed an enlargement in the submandibular and retropharyngeal lymph nodes, subcutaneous edema in the larynx region, and a temperature of 38.2ºC. According to the owner, cough was recurrent and had lasted about 12 months even after treatment with different kinds of antimicrobials. On radiographic exam, there was a marked decrease in the tracheal lumen and increased soft tissue radiopacity in the region adjacent to the narrowing. The animal was taken to surgery to remove the mass, but he died because of complications during surgery. The animal’s owner did not allow necropsy, but a fragment of the mass in the cranioesophageal was removed and sent for histological examination. The fragment was fixed in 10% formalin and processed using routine histological analysis. Macroscopically, the mass was light yellowish and ulcerated, and it measured 7.0 × 5.0 × 5.0 cm. In the middle of the ulcerated areas, there were yellow and firm granular structures that were consistent with kunkers. Histologically, extending from the tracheal adventitia to the thyroid, there was a large number of lymphocytes, macrophages, neutrophils, eosinophils, and multinucleated cells (foreign body type) and a well-defined focus of coagulative necrosis, which was surrounded by a thin border of macrophages. Within the necrotic areas, there were negative images of tubuliform hyphae. Grocott’s silver methanamine staining showed hyphae that had irregular branches, rare septa, smooth and parallel walls, and was impregnated by silver. Histological sections of the mass were subjected to immunohistochemistry. Hyphae were positive for Pythium insidiosum.Discussion: The diagnosis of pythiosis was based on macroscopic, histological findings and positive immunostaining for Pythium insidiosum. This report shows the unusual location of the disease in the horse, which made the clinical diagnosis of the disease complex. Extracutaneous forms of pythiosis in horses are less frequent than cutaneous forms. The etiopathogenesis of these forms is still unclear, but it has been suggested that previous lesions in the intestinal mucosa caused by plant material or pathogens may be predisposing factors for the appearance of the enteric form of the disease. It was not possible to observe if the animal’s other organs were affected because a necropsy could not be performed. The agent probably penetrated the esophageal epithelium and spread throughout the trachea and thyroid, but its origin cannot be determined. The radiographic findings in this study are compatible with neoplasms. However, inflammatory processes such as those caused by pythiosis should be included in the differential diagnosis of horses with swelling in the cranial portion of the esophagus.

Pythium insidiosum em equino: Relato de caso

Pythiosis is a chronic granulomatous condition affecting horses and other species such as dogs, cattle, goats, cats, wild animals and humans. It occurs in regions with tropical, subtropical or temperate climates, and in areas with accumulated water, bathed and lagoons. Brazil is among tropical countries as an endemic site of equine pythose.The etiologic agent in mammals is an oomycete of the Kingdom Stramenopila, Phylum Oomycota, Class Oomycetes, Order Pythiales, Family Pythiaceae, Genus Pythium, Species Pythium insidiosum. It is a parasite of aquatic plants, which through asexual reproduction produces zoospores that can infect animals. It causes great damages in the echinoculture and the prognosis of the disease depends on the extension of the lesions and compromise of structures such as tendons, joints and bone tissues. It is a disease that causes an infectious picture in the skin and subcutaneous region, however can present systemic picture, pulmonary, gastrointestinal, ocular, among others. The disease in horses characterized by eosinophilic granuloma formation with presence of necrotic masses called "kunkers". The “kunkers” present histologically as eosinophilic concretions of varied size, circular shape, irregular contours, composed of hyphae, collagen, arterioles and inflammatory cells. Many protocols for treatment have been used: chemical (antifungals), surgical and immunotherapy. The most appropriate treatment for pythiosis in horses is the surgical removal of granuloma combined with immunotherapy. However, the treatment is complicated by the unique characteristics of the agent that differs from the true fungi in the production of motile zoospores and in the composition of their cell wall. True fungi possess chitin in their wall, while Pythium contains cellulose and β-glucans, which makes it difficult to penetrate the drugs. In this work, it is proposed to report a case of pythiosis diagnosed in an equine attended at the Hospital of Veterinary Clinics (HCV) of UFRGS (Federal University of Rio Grande do Sul). A long and expensive treatment with complications and adverse reactions at the immunotherapeutic site was observed. However, the therapy was efficient in reducing the lesion, improving the infections condition of the skin and subcutaneous region.

Pythiosis cutánea en equinos tratados con acetonida de triamcinolona. Parte 3. Análisis histomorfométrico

Objetivo. El objetivo del estudio fue analizar histomorfométricamente el proceso de cicatrización en equinos con pythiosis tratados con acetonida de triamcinolona. Materiales y métodos. Se utilizaron 24 equinos con pythiosis, a un grupo se aplicó 50 mg de acetonida de triamcinolona intramuscular (GT), mientras que al otro grupo no fue aplicado tratamiento (GC). Fueron colectadas biopsias de tejido, procesadas, laminadas y coloreadas con hematoxilina eosina (H&E), tricrómico de Gómori (TG), picrosirius red/polarization (PR/P) y plata metanamina de Grocott (GMS). Fueron seleccionados y fotomicrografiados 10 campos histológicos, analizados con el software BioEstat 5.0, obteniéndose las cantidades tisulares de células como eosinófilos, neutrófilos, macrófagos, fibroblastos y colágeno a través de evaluación planimétrica por conteo de puntos. Resultados. En coloración de GSM, se observó disminución de hifas intralesionales del Pythium a los 16 días (p<0.05). En coloración de H&E, hubo disminución del proceso inflamatorio, evidenciado en eosinófilos (p=0.0001), neutrófilos (p=0,0001) y macrófagos (p=0.00001). En coloraciones de TG y PR/P, hubo aumento de fibroblastos, fibras colágenas y cambio progresivo de colágeno tipo III a tipo I, el aumento de fibroblastos fue significativo (p=0.0001) del día 16 al 40, la expresión de colágeno fue altamente significativa (p=0.0001) del día 16 hasta el final del estudio. Hubo correlación significativa entre neutrófilos y macrófagos (p=0.00018), colágeno y eosinófilos (p=0.03) y colágeno y fibroblastos (p=0.02). Los animales del GC no presentaron mejoría histomorfométrica durante el estudio. Conclusiones. Es posible concluir que la acetonida de triamcinolona produce recuperación histomorfométrica celular y tecidual en los equinos con pythiosis.

Pythiosis cutánea en equinos tratados con acetonida de triamcinolona. Parte 2. Descripción histológica e histoquímica

Objetivo. El objetivo del estudio fue realizar una descripción histológica e histoquímica del proceso de cicatrización de la pythiosis cutánea en equinos tratados con acetonida de triamcinolona. Materiales y métodos. Se Realizó un estudio de tipo descriptivo, no probabilístico en animales de conveniencia con pythiosis cutánea. Fueron utilizados 24 equinos con pythiosis, siendo aplicado 50 mg de acetonida de triamcinolona vía intramuscular a un grupo de 12 animales (GT) y en otro grupo no fue aplicado tratamiento (GC). Se realizaron biopsias de tejidos para evaluación histológica e histoquímica, en las coloraciones de hematoxilina eosina (H&E), tricrómico de Gómori (TG), picrosirius red/polarization (PR/P) y plata metanamina de Grocott (GMS). Resultados. Se observó que en el GT el proceso inflamatorio fue disminuyendo progresivamente, evidenciado en la disminución de la capa fibrino leucocitaria, PMN y de los fenómenos de Splendore Hoepli, así como mayor angiogénesis, epiteliogénesis y aumento de la cantidad de fibroblastos y fibras colágenas generales, así mismo en el cambio progresivo de colágeno tipo III a colágeno tipo I al final del proceso, además de que la presencia de hifas intralesionales de Pythium insidiosum disminuyó a la segunda semana. Ninguno de los animales del GC presentó mejoría en las características histológicas e histoquímicas de la pythiosis y se mantuvieron iguales al primer día durante todo el estudio. Conclusiones. La acetonida de triamcinolona es una buena alternativa terapéutica en el tratamiento de las heridas granulomatosas por pythiosis en equinos con 100% de recuperación clínica y demostrada con las constataciones histológicas e histoquímicas.

Pythiosis cutánea en equinos tratados con acetonida de triamcinolona. Parte 1. Caracterización clínica

RESUMENObjetivo. El objetivo del estudio fue caracterizar clínicamente el proceso de cicatrización de la pythiosis cutánea en equinos tratados con acetonida de triamcinolona. Materiales y métodos. Se realizó un estudio descriptivo, no probabilístico, de conveniencia. Fueron utilizados 24 equinos con pythiosis cutánea. A un grupo le fue aplicado 50 mg de acetonida de triamcinolona vía intramuscular (GT) y al otro grupo no fue aplicado tratamiento (GC). Se realizó caracterización clínica y macroscópica de la lesión cada 4 días hasta la recuperación completa del granuloma en el GT. Siendo verificada la disminución del exudado fibrinosanguinolento, prurito, presencia de trayectos fistulosos y salida de kunkers, también, fueron realizadas proyecciones radiológicas para evaluar el grado de compromiso óseo y fibrosis tecidual. Resultados. Macroscópicamente, los animales del GT presentaron diminución progresiva en las características clínicas de la enfermedad a los 16±1,4 días post aplicación del tratamiento. La contracción de la herida fue del 100% a los 60±3.4 días post aplicación del tratamiento en todos los granulomas del GT, siendo altamente significativa (p<0.0001). Radiológicamente, se encontró invasión a los tejidos subyacentes comprometiendo estructuras óseas, caracterizándose por fibrosis tisular, exostosis moderada, osteólisis y osteomielitis. Los animales del GC no presentaron mejoría en las características clínicas y macroscópicas de la pythiosis y se mantuvieron iguales durante todo el estudio. Conclusiones. La acetonida de triamcinolona es una buena alternativa terapéutica en el tratamiento de las heridas granulomatosas de pythiosis en equinos con 100% de recuperación clínica.

A Comparative Study of the Histopathology and Immunohistochemistry of Pythiosis in Horses, Dogs and Cattle

Twenty-one cases of pythiosis in horses (n = 10), dogs (n = 9) and cattle (n = 2) were investigated. The aetiology in all cases was confirmed by immunohistochemistry. Data related to the clinical course and outcome and localization of the lesions were obtained from pathology reports. The equine lesions consisted of fibrotic tissue with multiple, often coalescing, areas of immature granulation tissue encircling eosinophilic cores. Affected dogs had gastrointestinal and/or cutaneous lesions with either or both of a granulomatous/pyogranulomatous or necrotizing eosinophilic inflammatory reaction. In cattle, cutaneous lesions were characterized by multifocal to coalescing granulomas with surrounding fibrosis. The number of intralesional hyphae, the distribution of hyphae, the presence of angioinvasion and the nature of the local inflammatory reactions were associated with the different types of lesions observed.

Teste de ELISA indireto para o diagnóstico sorológico de pitiose

A pitiose, doença granulomatosa de eqüinos causada pelo oomiceto Pythium insidiosum, tem como característica a evolução rápida seguida de morte dos animais. Estas mortes muitas vezes são causadas por diagnósticos errôneos ou demorados quando os doentes já não respondem ao tratamento. Este trabalho teve por objetivo a padronização do ensaio imunoenzimático indireto (ELISA) para diagnóstico sorológico de pitiose em eqüinos e coelhos, visando a diminuição de erros e de tempo necessário para o diagnóstico. Para o desenvolvimento e validação do teste foram utilizadas 72 amostras de soro de eqüinos saudáveis e 44 soros de eqüinos com pitiose confirmada. Os resultados da validação do ELISA para eqüinos foram: sensibilidade 97,72%, especificidade 90,27%, valor preditivo positivo 86%, valor preditivo negativo 98,4% e eficiência de 93,1%. Para coelhos, o teste foi padronizado com 48 amostras de soro de animais saudáveis e 24 amostras de coelhos imunizados com antígenos de P. insidiosum. Os resultados foram: sensibilidade 91,66%, especificidade 95,83%, valor preditivo positivo 91,66%, valor preditivo negativo 95,83% e eficiência de 94,44%. Os resultados deste trabalho demonstram que o ensaio imunoenzimático indireto é um método seguro e eficaz para o diagnóstico sorológico da pitiose.

Pitiose cutânea em eqüinos: 14 casos

A pitiose cutânea é uma doença crônica que afeta preferencialmente eqüinos e, raramente, bovinos, caninos, felinos e seres humanos. É causada por Pythium insidiosum, um fungo aquático. São relatados quatorze casos de pitiose cutânea em eqüinos do município de Uruguaiana, Rio Grande do Sul. As lesões se localizam, principalmente na região distal dos membros pélvicos e caracterizam-se macroscopicamente por granulomas subcutâneos, ulcerados com exsudação sero-sanguinolenta. Microscopicamente há áreas irregulares de necrose circundadas por infiltrado inflamatório constituído por eosinófilos, neutrófilos, macrófagos e abundante tecido fibrovascular. São descritos e discutidos os métodos de diagnóstico, sinais clínicos, achados de necropsia, histopatologia, diagnóstico diferencial e tratamento

Pitiose eqüina no Pantanal brasileiro: aspectos clínico-patológicos de casos típicos e atípicos

A pitiose eqüina é doença endêmica no Pantanal Brasileiro e causa prejuízos significativos a eqüinocultura. Neste trabalho são relatados 16 casos de pitiose subcutânea em eqüinos no Pantanal Sul-Matogrossense, que foram divididos em onze casos típicos e cinco casos atípicos, de acordo com o quadro clínico e o tempo de duração das lesões. O diagnóstico foi confirmado pela detecção de anticorpos específicos pelo teste ELISA, isolamento do agente e histopato-lógico. A duração da doença variou entre 1 e 6 meses nos casos típicos e superior a 12 meses nos casos atípicos. As lesões dos casos típicos caracterizavam-se por granulomas subcutâneos, ulcerados, com abundante secreção serossangui-nolenta e prurido. Nos casos atípicos foram observadas lesões subcutâneas caracterizadas por grandes massas "tumorais" circunscritas, recobertas por pele escura, sem ulcerações e com pouca secreção. Os animais estavam em bom estado nutricional e as lesões apresentavam-se de aspecto organizado, às vezes pedunculadas. Histologicamente, foi observado tecido de granulação com muitos eosinófilos nos casos típicos, enquanto os atípicos, se caracterizaram por hiperplasia pseudo-epiteliomatosa da epiderme e infiltrado eosinofílico. As características clínicas e histopato-lógicas completas das duas formas clínicas e os possíveis fatores responsáveis pelas diferenças entre as duas formas são apresentados e discutidos.

Cutaneous pythiosis in horses from Brazil.

Equine pythiosis was studied in five animals from two farms located in a swampy region of southern Brazil (Rio Grande do Sul State). Granulomatous lesions exuding necrotic material and containing a central yellow and firm tissue core, the 'kunker', were observed on the top of the nose of one horse, on the abdomen of two horses and on the hind limbs of two other animals. Direct microscopic preparations, histopathological examination of lesion material, and macroscopic and microscopic characteristics of the isolates confirmed the diagnosis of pythiosis. Surgical intervention of the inflammatory processes, intravenous potassium iodide and topical application of copper sulphate were used without success.

Immunodiffusion test for diagnosing and monitoring pythiosis in horses.

A practical, sensitive, and specific immunodiffusion test was developed for diagnosing and monitoring pythiosis in horses. Culture filtrates, a soluble cell mass, and trypsinized Pythium sp. antigens were evaluated against prepared rabbit anti-Pythium sp. serum and pythiosis horse case sera. The culture filtrate antigens demonstrated the greatest capacity for detecting precipitins and the greatest stability during storage. In contrast, the trypsinized antigens had the weakest capability for detecting multiple precipitins and the poorest stability. The 13 sera from horses with proven active pythiosis were positive in immunodiffusion tests with the culture filtrate antigens. Each serum contained from three to six precipitins. Treated horses lost precipitins, and some became antibody negative. No false-positive reactions were noted in tests with sera from normal horses and humans or with sera from a variety of heterologous horse and human infections.