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Geographic distribution of Pythium insidiosum infections in the United States.
Abstract: To describe the geographic distribution of infections caused by Pythium insidiosum in dogs, horses, and other animal species in the US. For the last 20 years, we have collected data from cases of pythiosis in 1,150 horses, 467 dogs, and other species (59) from various geographic locations in the US. Due to lost data (from 2006 to 2016), the selected cases include years 2000 to 2005 and 2016 to 2020. The selection of cases was based on infected host clinical features, serum samples demonstrating strong positive anti-P insidiosum IgG titers in serologic assays, and positive results on ≥ 1 of the following diagnostic modalities: microbial culture on 2% Sabouraud dextrose agar, histologic evaluation, PCR assay, and wet mount cytologic evaluation (with potassium hydroxide). Most confirmed P insidiosum infections were found in horses and dogs in the southeastern US. Interestingly, in Texas, no cases were found west of longitude 100°W. Few pythiosis cases were diagnosed in west-coast states. Equine cases were more often diagnosed during summer and fall months, but canine cases were more often diagnosed between September and February. Cases in other species were discovered in the same geographic areas as those in dogs and horses. To our knowledge, this is the first report providing the ecological distribution of P insidiosum infection in affected species in the US. Results of this study illustrated the importance of including P insidiosum in the differential diagnostic scheme of nonhealing skin lesions or intestinal granulomatous masses, particularly in dogs and horses inhabiting or having visited endemic areas.
Publication Date: 2021-12-27 PubMed ID: 34968184DOI: 10.2460/javma.20.10.0595Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
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This research study focuses on the geographical distribution of infections caused by Pythium insidiosum in different animal species including dogs, horses, and others, in the United States. The researchers have made use of data collected in a period spanning two decades, to seek patterns and understand the ecological distribution of this infection.
Collection of Data and Methodology:
- The researchers in this study have gathered data on infections caused by Pythium insidiosum over the last 20 years.
- The data spans cases from 2000 to 2005 and then 2016 to 2020, as the data between 2006 and 2016 was lost.
- They have studied cases including 1,150 horses, 467 dogs, and 59 species from various geographical locations in the U.S.
- The selection of cases for the study was based on clinical features of the infected host, serum samples demonstrating anti-P insidiosum IgG titers in serologic tests, and positive results on various diagnostic modalities like microbial culture, histologic evaluation, PCR assay, and wet mount cytologic evaluation with potassium hydroxide.
Findings of the Research:
- The research found that most confirmed P insidiosum infections were prevalent in horses and dogs in the southeastern part of the U.S.
- No cases were found west of longitude 100°W in Texas.
- Few cases of Pythium insidiosum infections were diagnosed in the western coastal states.
- Horses were more often diagnosed with the infection during the summer and fall months, while cases in dogs were more frequently found between September and February.
- Cases in other animal species were found in the same geographical areas as those in dogs and horses.
Significance of the Research:
- This study is reportedly the first of its kind to provide an ecological distribution of P. insidiosum infection in the affected species in the U.S.
- The results highlight the importance of including P. insidiosum in the differential diagnosis of nonhealing skin lesions or intestinal granulomatous masses, particularly in dogs and horses living in or having visited known endemic areas.
Cite This Article
APA
Nguyen D, Vilela R, Miraglia BM, Vilela G, Jasem-Alali N, Rohn R, Glass R, Hansen RD, Mendoza L.
(2021).
Geographic distribution of Pythium insidiosum infections in the United States.
J Am Vet Med Assoc, 260(5), 530-534.
https://doi.org/10.2460/javma.20.10.0595 Publication
Researcher Affiliations
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI.
- Biomedical Laboratory Diagnostics Program, Michigan State University, East Lansing, MI.
- Faculty of Pharmacy, Federal University of Minas Gerais, Minas Gerais, Brazil.
- Faculty of Pharmacy, Federal University of Minas Gerais, Minas Gerais, Brazil.
- Biomedical Laboratory Diagnostics Program, Michigan State University, East Lansing, MI.
- Biomedical Laboratory Diagnostics Program, Michigan State University, East Lansing, MI.
- Biomedical Laboratory Diagnostics Program, Michigan State University, East Lansing, MI.
- Pan American Veterinary Laboratories, Lexington, TX.
- SolidTech Animal Health, Inc, Newcastle, OK.
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI.
- Biomedical Laboratory Diagnostics Program, Michigan State University, East Lansing, MI.
MeSH Terms
- Animals
- Dog Diseases / epidemiology
- Dog Diseases / parasitology
- Dogs
- Horse Diseases / epidemiology
- Horse Diseases / parasitology
- Horses
- Polymerase Chain Reaction / veterinary
- Pythiosis / epidemiology
- Pythium / genetics
- Texas
- United States / epidemiology
Citations
This article has been cited 8 times.- Elshafie NO, Hanlon J, Malkawi M, Sayedahmed EE, Guptill LF, Jones-Hall YL, Santos AP. Nested PCR Detection of Pythium sp. from Formalin-Fixed, Paraffin-Embedded Canine Tissue Sections. Vet Sci 2022 Aug 19;9(8).
- Yolanda H, Krajaejun T. Global Distribution and Clinical Features of Pythiosis in Humans and Animals. J Fungi (Basel) 2022 Feb 11;8(2).
- Brodkin J, Frederick SW, Rick M, Chapman PS. Vitamin D-Mediated Hypercalcemia in a Dog With Putative Cutaneous Pythiosis. Clin Case Rep 2025 Dec;13(12):e71594.
- Moharam SA, Sadek AM, Abdelzaher HMA, Shoulkamy MA, Arafat HH. A novel, cheap and easy preparing selective medium for isolation of Pythium species. AMB Express 2025 Oct 13;15(1):148.
- Vilela R, Grady SC, Vilela PR, Mendoza L. Geographical distribution of human pythiosis in the USA. Microbiol Spectr 2025 Jan 7;13(1):e0210324.
- Yurayart N, Jittorntam P, Kumsang Y, Rujirawat T, Jiaranaikulwanich A, Krajaejun T. Enhanced detection of Pythium insidiosum via lipid profiling with matrix-assisted laser desorption ionization time of flight mass spectrometry. IMA Fungus 2024 Nov 1;15(1):32.
- Pereira DIB, Botton SA, Ianiski LB, Braga CQ, Maciel AF, Melo LG, Zambrano CG, Bruhn FRP, Santurio JM. Equidae pythiosis in Brazil and the world: a systematic review of the last 63 years (1960-2023). Braz J Microbiol 2024 Sep;55(3):2969-2981.
- Loreto ES, Tondolo JSM, Zanette RA. Treating Pythiosis with Antibacterial Drugs Targeting Protein Synthesis: An Overview. J Fungi (Basel) 2024 Mar 22;10(4).
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