Felis ISSN 2398-2950

Pythiosis

Contributor(s): Susan Dawson, Rhea Morgan

Introduction

  • Cause: rare infection with Pythium insidiosum Pythium insidiosum (formerly known as Hyphomyces destruens, Pythium destruens, Pythium gracile) an aquatic fungus.
  • Signs: cutaneous, nasal, and gastrointestinal signs.
  • Diagnosis: serology, PCR assay, histopathology.
  • Treatment: surgical excision, itraconazole.
  • Prognosis: poor to guarded

Pathogenesis

Etiology

  • Pythium insidiosum - an oomycete.
  • Oomycetes are soil or water saprophytes.
  • They are not true fungi.
  • They produce motile flagellate zoospores, which are the infective stage.
  • Their plasma membranes lack sterols, which is the site of activity of many antifungal drugs.

Predisposing factors

General

  • Residing in an area where the organism is endemic.
  • Contact with warm, stagnant water containing the infective stage.

Pathophysiology

  • The organism may gain entrance to the body through breaks in the skin, through breaks in the nasal mucosa, or by invading the gastrointestinal mucosa following ingestion.
  • The organism has a predilection for the stomach, duodenum and ileum, causing an infiltrative granulomatous gastroenteritis.
  • Isolated masses may develop within the gastrointestinal tract.
  • Cutaneous lesions begin as nonhealing wounds or ulcerated nodules.
  • Necrosis of the skin and subcutaneous tissues may result.
  • Cutaneous lesions are not often accompanied by gastrointestinal infection.

Timecourse

  • Incubation poorly defined.
  • Duration is weeks to months.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Grooters A M, Leise B S, Lopez M K et al (2002) Development and evaluation of an enzyme-linked immunosorbent assay for the serodiagnosis of pythiosis in dogs. J Vet Intern Med 16 (2), 142-146 PubMed.
  • Znajda N R, Grooters A M & Marsella R (2002) PCR-based detection of Pythium and Lagenidium DNA in frozen and ethanol-fixed animal tissues. Vet Dermatol 13 (4), 187-194 PubMed.
  • Thomas R C & Lewis D T (1998) Pythiosis in dogs and cats. Compend Contin Educ Pract Vet 20 (1), 63-75 VetMedResource.
  • Duncan D, Hodgin C, Bauer R & Brignac M (1992) Cutaneous pythiosis in four cats. Vet Pathol 29, 5.
  • Bissonnette K W, Sharp N J, Dykstra M H et al (1991) Nasal and retrobulbar mass in a cat caused by Pythium insidiosum. J Med Vet Mycol 29 (1), 39-44 PubMed.

Other sources of information

  • Foil CS (1998) Miscellaneous fungal infections. In\; Greene CE (ed)Infectious diseases of the Dog and Cat. 2nd Ed. WB Saunders, Philadelphia, pp.420-430.
  • Taboada J (2002) Systemic mycoses. In: Morgan RV, Bright RN, Swartout MS (eds);Handbook of Small Animal Practice. 4th Ed. WB Saunders, Philadelphia, pp.1072-1089.


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