Detection of Myxobolus cerebralis (Bivalvulida: Myxobolidae) in two non-Tubifex tubifex oligochaetes in the southeastern USA
Bibliographic record
Abstract
Myxobolus cerebralis (Hofer, 1903), the etiological agent of salmonid whirling disease, reportedly matures in only the oligochaete 'Tubifex tubifex'. The concept of 'T. tubifex' is problematic because it is renowned as a species complex (or having 'strains'), and many sequences ascribed to this taxon in GenBank are misidentified or indicate several cryptic species. These facts cast doubt on the long-held notion that M. cerebralis is strictly host-specific to the single definitive host, T. tubifex. Herein, as part of an ongoing regional whirling disease monitoring project, oligochaetes (452 specimens) were collected from 31 riverine sites in western North Carolina (August through September 2015) and screened for infection by M. cerebralis. The species-specific nested PCR for M. cerebralis was positive for 8 oligochaete specimens from the French Broad River Basin (Mill Creek and Watauga River) and New River Basin (Big Horse Creek). We individually barcoded these M. cerebralis-positive oligochaete specimens using cytochrome oxidase 1 (CO1) primers and then conducted a Bayesian inference phylogenetic analysis. We identified 2 oligochaete genotypes: one sister to a clade comprising Limnodrilus udekemianus (Haplotaxida: Naididae) and another sister to Limnodrilus hoffmeisteri. This is the first detection of M. cerebralis from an oligochaete in the SE USA and the first detection of M. cerebralis from an oligochaete other than T. tubifex. These results suggest that other non-T. tubifex definitive hosts can harbor the pathogen and should be considered in the context of fish hatchery biosecurity and monitoring wild trout streams for M. cerebralis and whirling disease in the southeastern USA.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".