{
  "id": 8828623,
  "title": "Geographic distribution of Adult Salmon Enteritis (ASE), Enterocytozoon schreckii, and Ceratonova shasta in Chinook Salmon Oncorhynchus tshawytscha (Walbaum, 1792) in Oregon and Washington state and expanded histopathologic description of ASE",
  "url": "https://urgent.news/2026/09/20/geographic-distribution-of-adult-salmon-enteritis-ase-enterocytozoon",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-20T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.14.751509v1?rss=1"
  },
  "original_language": "en",
  "account": "Adult salmon enteritis (ASE) is a severe intestinal disease impacting spring Chinook Salmon (Oncorhynchus tshawytscha) in the Pacific Northwest. ASE is strongly linked to pre-spawn mortality (PSM), a major concern for vulnerable populations and ongoing Chinook Salmon conservation efforts. This study investigates the geographical spread of ASE in Oregon and Washington watersheds, explores its connection to two prevalent parasites (Ceratonova shasta and Enterocytozoon schreckii), and offers an in-depth histopathological analysis of the disease.\n\nResearchers analyzed intestinal samples from 259 adult spring Chinook Salmon sourced from various hatcheries in the Columbia River Basin and Puget Sound between 2022 and 2025. The examination utilized traditional histopathology, specific stain techniques, and immunohistochemistry. ASE was notably prevalent across all Columbia Basin populations, characterized by chronic ulcerative and necrotizing enteritis, but was notably absent in Puget Sound populations. Ceratonova shasta was found to be highly prevalent in most Columbia Basin locations (10-100%), while Enterocytozoon schreckii exhibited varying prevalence rates (0-67%).\n\nCommon histopathological findings associated with ASE included 10% or more mucosal ulceration, mixed inflammation spreading through the lamina propria and into adjacent intestinal layers, and breakdown of the stratum granulosum. In instances of chronic ASE lesions, researchers further examined granulation tissue formation. The study suggests that cold water holding of spawning adults can slow disease progression and decrease PSM without halting ASE development. These findings highlight ASE as a geographically confined disease within the Columbia Basin, potentially influenced by diverse environmental factors such as water temperature and parasitic exposures.",
  "summary": "Adult salmon enteritis (ASE) is a severe intestinal disease affecting spring Chinook Salmon (Oncorhynchus tshawytscha) in the Pacific Northwest. ASE is strongly associated with pre-spawn mortality (PSM), a critical concern for endangered populations and continued Chinook Salmon management. This study characterizes the geographic distribution of ASE across Oregon and Washington watersheds,…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}