Increased Recognition of Powassan Encephalitis in the United States, 1999–2005
Bibliographic record
Abstract
Powassan virus (POWV) disease is a rare human disease caused by a tick-borne encephalitis group flavivirus maintained in a transmission cycle between Ixodes cookei and other ixodid ticks and small and medium-sized mammals. During 1958-1998, only 27 POWV disease cases (mostly Powassan encephalitis) were reported from eastern Canada and the northeastern United States (average, 0.7 cases per year). During 1999-2005, nine cases (described herein) of serologically confirmed POWV disease were reported in the United States (average, 1.3 cases per year): four from Maine, two from New York, and one each from Michigan, Vermont, and Wisconsin. The Michigan and Wisconsin cases are the first ever reported from the north-central United States. Of these nine patients, 5 (56%) were men, the median age was 69 years (range: 25-91 years), and 6 (67%) had onset during May-July. All but one patient developed encephalitis with acute onset of profound muscle weakness, confusion, and other severe neurologic signs. In one case, no neurologic symptoms were present but the presence of pleocytosis, an elevated cerebrospinal fluid (CSF) protein concentration, and POWV-specific immunoglobulin M in CSF suggested neuroinvasion. All patients recovered from their acute disease, but most had long-term neurologic sequelae. Periresidential ecologic investigations were performed in three cases, including tests of local mammals and ticks for evidence of POWV infection. Woodchucks (Marmota monax), striped skunks (Mephitis mephitis), and a raccoon (Procyon lotor) collected at two of the Maine case-patients' residences had neutralizing antibody titers to POWV. I. cookei were found on woodchucks and skunks and questing in grassy areas of one of these residences; all were negative for POWV. Although POWV disease is rare, it is probably under-recognized, and it causes significant morbidity, and thus is an additional tick-borne emerging infectious disease entity. Because no vaccine or specific therapy is available, the basis of prevention is personal protection from ticks (or "tick hygiene") and reduced exposure to peridomestic wild mammals.
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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 | 0.002 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".