Pythiosis in sheep from Paraná, southern Brazil

Abstract

This paper reports pythiosis in a sheep from southwestern Paraná, Brazil, confirmed by indirect ELISA (Enzime-Linked Immunosorbent Assay) and immunohistochemistry, as well as it describes the macro and microscopic injuries, in order to understand the pathogenicity. A 4-year-old ewe from a flock of 30 Santa Inês sheep, raised semi-extensively with access to a weir, showed cachexia, bilateral enlargement in nasal region, a serous and bloody secretion with a fetid odor from its nose and swollen submandibular and retropharyngeal lymph nodes. Blood collection was performed trough jugular vein puncture in order to make complete blood cell count (CBC) and to obtain serum for the subsequent serological examination. As the hematological counts were within the normal range for sheep, the animal was euthanized and submitted to necropsy. Indirect ELISA resulted positive for pythiosis. Necropsy revealed necrosis of the hard palate with a diameter of 3.5cm and extending up to the nasal cavity, forming a fistula. Submandibular and retropharyngeal lymph nodes were enlarged and edematous on section. Microscopic findings for submandibular and retropharyngeal lymph nodes consisted in moderate infiltration of eosinophils mainly in the subcapsular sinus, characterizing reactive eosinophilic lymphadenitis. The nasal cavity revealed rhinitis and oral cavity stomatitis with necro-eosinophilic and pronounced multifocal granulomatous infiltration and presence of hyphae. Hyphae found in palate and nasal cavity were positive for Pythium insidiosum by Grocott's method and immunohistochemistry, the last one considered to be confirmatory for the pathogen diagnostic. This report has an important epidemiological aspect, as it is the first case of pythiosis in sheep confirmed by serology in South Brazil and an alert of possible infection by the pathogen in floodplains.

Diseases caused by Pythium insidiosum in sheep and goats: a review

“…7,17,22,25,27,31 This form of the disease may occur sporadically but can also be epizootic, with morbidity of 0.6–20% and lethality of 100%, and it is an important cause of sheep death and economic losses. 3,7,17,22,25,27,31…”

“…A unique case of rhinofacial pythiosis was reported in the state of Paraná, southern Brazil, in a flock of 30 sheep grazing in a paddock that has a weir as a source of drinking water. 3…”

“…Pythiosis is an infectious disease of animals and humans 9 first observed in 1884 affecting horses in India. 2 It is common in horses 14,16,23 but may also affect cattle, 8,10,20 dogs, 11,19 cats, 24 several zoo animal species, 9,14 birds, 18,29 sheep, 3,7,17,21,22,25,27,28,30,31 and goats. 6 All cases of ovine pythiosis have been reported in Brazil, as was the only case of the disease described in a goat.…”

Sublingual pythiosis in a cat

“…There is one record of animals infected with an oral form of pythiosis. A case of pythiosis involving the hard palate and nasal cavity in a sheep from southwestern Paraná, southern Brazil, was confirmed by indirect enzyme-linked immunosorbent assay and immunohistochemistry [ 14 ]. Interestingly, two cases of canine chronic esophagitis caused by P. insidiosum occurred previously in rural Tennessee, USA [ 15 ].…”

History and Perspective of Immunotherapy for Pythiosis

“…This process leads to the non-protective Th2-mediated immunity, where eosinophils are predominantly recruited, together with other cell types, such as mast cells, neutrophils, giant cells, and plasma cells, into the infection area [18,28,66,160,199,217,247]. The eosinophils surround the P. insidiosum hyphae inside necrotic tissues, producing the histological phenomenon called "Splendore-Hoeppli" [49,105,[248][249][250]. P. insidiosum might employ the accumulated eosinophilic materials as a protective shield against host immunity [122].…”