Dated, cited developments in tick surveillance and tick-borne disease across Canada and the United States.
Written by Phillip George · Last updated: August 30, 2026
Update cadence: monthly. This page is reviewed and updated once a month, in the first week of the month. It is maintained by one person, so a weekly promise would be a promise we would break. If an entry below is more than six weeks old, the log is overdue and you should treat the linked primary sources as the current record rather than our summary.
This is a working log, not a headline feed. Each entry is a short summary written from the primary document — a surveillance report, a peer-reviewed paper, a health authority advisory — followed by a plain reading of what the finding does and does not change for someone living in the affected area. We link the source so you can check us.
Tick coverage in general news is unusually prone to alarm inflation. A pathogen detected in a pooled sample of ticks becomes "deadly virus spreading"; a preliminary case count becomes an epidemic. The distinction that matters most, and the one most often lost, is between a pathogen found in ticks and a person who got sick. Those are different measurements with different implications, and this log keeps them separate.
2026 log
· Maine, United States
Maine confirms a fourth Powassan virus case of 2026
The Maine Center for Disease Control and Prevention confirmed Powassan virus infection in an adult in Penobscot County, the state's fourth confirmed case of the year. The earlier three were in York, Lincoln and Penobscot counties. Maine's first 2026 case, announced in a June clinician advisory, developed non-neuroinvasive illness and was not hospitalised — a reminder that Powassan infection is not uniformly severe, though it can be. Maine CDC has recorded 41 Powassan cases in state residents since 2000, and roughly 1% of deer ticks submitted to the University of Maine tick laboratory test positive for the virus.
What this means: Powassan is the one tick-borne virus endemic to Maine, and unlike Lyme disease it has no antibiotic treatment, so prevention is the whole strategy. Four cases in a state of 1.4 million people is a small number in absolute terms. It matters clinically because Powassan can transmit within about 15 minutes of attachment, so the "remove it within 24 hours and you're fine" rule of thumb that works reasonably well for Lyme disease does not apply. What it does not mean: there is no evidence of an outbreak, and case counts in the single digits move around year to year for reasons that include how often clinicians think to order the test.
European regulator begins reviewing a Lyme disease vaccine
The European Medicines Agency validated Pfizer and Valneva's marketing authorisation application for PF-07307405, a six-valent OspA-based Lyme disease vaccine candidate previously known as VLA15, and has started its assessment. Validation is an administrative milestone — it means the dossier is complete enough to review, not that the vaccine works or will be approved. The application rests on the Phase 3 VALOR results announced in March 2026. Pfizer has said it is working with the US Food and Drug Administration toward a Biologics License Application but has not published a submission date.
What this means: there has been no licensed human Lyme disease vaccine anywhere since LYMErix was withdrawn from the US market in 2002, so a regulator formally opening a file is the furthest this field has advanced in more than two decades. What it does not mean: nothing is available to patients now, in Europe or North America, and EMA review timelines run months to years. Nobody should defer tick-bite prevention on the strength of a pending application.
Blacklegged tick infection rates in western North Carolina match the Northeast
CDC's Morbidity and Mortality Weekly Report published a community-based surveillance study from Biltmore Forest, a wooded town in Buncombe County near Asheville. Researchers from the University of South Carolina, UNC Chapel Hill and NC State dragged for ticks monthly at 22 residential properties between November 2024 and August 2025, collecting 373 ticks in all, of which 287 (76.9%) were blacklegged ticks (Ixodes scapularis). Nineteen of 48 adult blacklegged ticks — 39.6% — carried Borrelia burgdorferi sensu stricto, alongside three of seven nymphs. Testing was done at CDC's Division of Vector-Borne Diseases in Fort Collins, Colorado. The team also found Borrelia miyamotoi, which causes hard tick relapsing fever, and the human-active strain of Anaplasma phagocytophilum; the authors write that these might represent the farthest south either pathogen has been identified in blacklegged tick populations.
What this means: a roughly 40% infection rate in adult ticks is the kind of figure normally quoted for Connecticut or Pennsylvania, not southern Appalachia. North Carolina's Division of Public Health already advises clinicians to consider single-dose doxycycline prophylaxis for qualifying bites in ten western counties — Buncombe, Madison, Yancey, Mitchell, Avery, Watauga, Ashe, Alleghany, Surry and Stokes — selected because they recorded at least 16 Lyme cases per 100,000 residents in the previous five years or sit between two such counties. The practical consequence is diagnostic: a clinician who was trained that Lyme disease is a Northeast problem may not test for it. What it does not mean: this is one small town, the authors say so, and 48 adult ticks is a small denominator with a wide confidence interval (26.0–54.6%). It is not a statewide infection rate.
Nebraska becomes the ninth state to detect Heartland or Bourbon virus in local ticks
The Nebraska Department of Health and Human Services and the Nebraska Public Health Laboratory added Heartland and Bourbon virus screening to their tick surveillance in 2024. A preprint posted in August 2026 reports the first detections of both viruses in Nebraska lone star ticks (Amblyomma americanum): complete Heartland virus genomes from three PCR-positive tick pools in two eastern counties, and one Bourbon virus genome from a single pool. Reporting on the work puts the collection at more than 7,000 lone star ticks gathered across the state between 2022 and 2026, with both viruses found in Sarpy County and Heartland virus in Richardson County — both in the southeast, adjacent to Missouri and Kansas. The Heartland genomes cluster with viruses isolated in Missouri in the early 2000s, consistent with the tick carrying the virus westward as its range expanded. No human case has been diagnosed in Nebraska.
What this means: the honest headline is a diagnostic gap, not a body count. Neither virus has a commercially available clinical test in the United States, so a patient with fever, fatigue and low blood counts after a tick bite is only counted if a physician thinks to send samples to a state laboratory or CDC. Detection in ticks tells clinicians in southeastern Nebraska that the question is now worth asking. What it does not mean: a virus found in a pooled tick sample is not a person who is ill. Both viruses remain rare, and this is a preprint — it has not completed peer review.
Canada records its highest Lyme disease count: 7,105 preliminary cases in 2025
The Public Health Agency of Canada's monitoring page now lists a preliminary 7,105 reported Lyme disease cases for 2025, up from 5,809 in 2024 and 4,785 in 2023. That is the highest annual figure since national reporting began in 2009, when 144 cases were reported, and it brings the 2009–2025 cumulative total to 28,033. PHAC notes on the same page that the national surveillance case definition was revised in 2016 and again in 2024, and that those revisions affect how the trend should be read.
What this means: the direction is real. Blacklegged tick populations have expanded across southern Ontario, Québec, the Maritimes and parts of Manitoba, and more people are being exposed. What it does not mean: 7,105 is not the number of Canadians who caught Lyme disease in 2025. It is the number reported through surveillance, and three separate things inflate or deflate it independently of actual risk — a changed case definition, how hard each province looks, and how many infections never reach a laboratory at all. We work through those caveats in detail on our statistics page.
Ontario blacklegged tick reports up 72.8% at the halfway point of 2026
Analysis of eTick.ca public submissions through 23 June 2026 found 8,735 ticks reported in Ontario, a 50.2% increase over the same period in 2025, with blacklegged tick reports specifically up 72.8% to 3,126. Ontario accounted for 52.9% of all Canadian tick reports and 63.7% of blacklegged tick reports in the covered provinces. The same reporting listed 2026 Lyme case counts supplied by four provinces — 600 in Nova Scotia, 296 in Ontario, 155 in Québec and 21 in New Brunswick — totalling at least 1,072. No national 2026 count exists yet.
What this means: eTick is a public photo-submission service, so a jump in submissions measures encounters and awareness together, not tick abundance on its own. Even allowing for that, a 72.8% rise concentrated in the Lyme vector rather than in ticks generally is a signal worth acting on if you live in southern Ontario. What it does not mean: the provincial case figures above are partial in-season numbers collected by a news organisation from individual provinces, not comparable PHAC surveillance data, and they will be revised. Do not add them together and treat the result as a national total.
First human Bourbon virus infection documented in New York State
A Stony Brook Medicine team published a serology study in the American Journal of Tropical Medicine and Hygiene covering 107 patients aged 20 to 93 who presented in Suffolk County with acute fever after a recent tick bite between 2019 and 2024. Blood samples went to the New York State Department of Health for plaque-reduction neutralisation testing. Two patients had neutralising antibodies to Bourbon virus and one to Heartland virus; in two of those three, a fourfold rise in titre indicated acute or recent infection. This is the first documented human Bourbon virus infection in New York State. None of the 107 tested positive for Powassan virus. Bourbon virus RNA had already been found in a Long Island lone star tick in 2019, so the vector was known to be present; what was missing was a confirmed human case.
What this means: the finding came out of a retrospective look at stored blood, which is the point. Because no clinical laboratory offers a Bourbon virus test, cases like this are invisible unless a research group goes looking. Any similar illness on Long Island since then is unlikely to have been identified. What it does not mean: two antibody-positive results out of 107 febrile patients is not evidence that Bourbon virus is common, and this study says nothing about how severe a typical infection is. Lyme disease, anaplasmosis and babesiosis remain vastly more likely explanations for a fever after a tick bite in Suffolk County.
Public Health Ontario publishes its 2026 blacklegged tick risk area map
Public Health Ontario's Vector-Borne Disease Tool was updated with a 2026 blacklegged tick risk area map reflecting newly identified or expanded risk areas based on 2025 surveillance data, finalised 2025 human case and vector figures, and a new tab showing passive tick submissions from the public and from healthcare providers, drawn from the agency's laboratory system and supplemented with eTick data. The dashboard is updated weekly for human case counts and annually for tick data.
What this means: if you want to know whether your own township is inside a designated risk area, this dashboard is the authoritative answer for Ontario and it is more current than any summary we could write. What it does not mean: being outside a risk area is not the same as being safe. Ontario's own guidance is that blacklegged ticks travel on birds and deer and it is possible, if less likely, to encounter an infected tick almost anywhere in the province. Our Ontario guide covers the regional picture.
Phase 3 VALOR trial reports more than 70% efficacy but misses its statistical threshold
Pfizer and Valneva released topline results from VALOR (NCT05477524), a Phase 3 trial of the OspA-based Lyme vaccine candidate PF-07307405 run at high-incidence sites in the United States, Canada and Europe in participants aged five and older. Two pre-specified analyses put efficacy at 73.2% from 28 days after the fourth dose (95% CI 15.8–93.5) and 74.8% from one day after (95% CI 21.7–93.9). Fewer Lyme cases accrued during the study than expected, so the pre-set criterion for the primary endpoint — a confidence-interval lower bound above 20 — was not met in the first analysis, though it was in the second. The companies reported no safety concerns identified at the time of analysis and said they would file with regulators.
What this means: a technical miss on a primary endpoint driven by low case accrual is a different problem from a vaccine that does not work, and the point estimate is squarely in the range of a useful vaccine. Regulators will decide how much weight the second analysis carries. What it does not mean: those confidence intervals are wide — the lower bounds are 15.8% and 21.7% — so the true effect could be considerably smaller than 73%. "More than 70% efficacy" is the point estimate, not a guarantee.
Peer-reviewed analysis quantifies how Nova Scotia's case definition change moved the numbers
The Canada Communicable Disease Report published an analysis of Nova Scotia's switch, on 1 January 2023, to a Lyme disease case definition based on laboratory evidence alone, without the previously required clinical confirmation. Applying the new definition retrospectively to 2018–2022 produced 4,238 cases against the 1,745 actually reported under the old one, and 2023 added a further 2,058 cases under the new definition. The authors report that the revised definition yields a clear upward incidence trend where the former definition produced year-to-year noise with no clear direction. Nova Scotia's own surveillance report states plainly that 2023 counts should not be compared with earlier years.
What this means: a large part of the jump in Canada's national totals from 2022 to 2023 is a measurement change in one province, not a sudden change in risk there. PHAC's own summary attributes the 2023 increase partly to this revision, noting Nova Scotia reported more than six times as many cases in 2023 (2,057) as in 2022 (326). What it does not mean: the change was not a fudge. Nova Scotia moved because clinical evidence was under-reported and lab-confirmed cases were being dropped, and in a high-incidence jurisdiction a positive result is less likely to be a false positive. The new figures are probably closer to the truth; they are simply not comparable with the old ones.
An item qualifies for this log if it changes what a reader should know or do, and if it can be traced to a document we can read ourselves. In practice that means one of:
a provincial, state or territorial health authority, including clinician advisories and annual surveillance reports;
a peer-reviewed paper, cited by DOI, or a clearly labelled preprint;
a university extension service or a named research programme publishing its own surveillance data;
a regulatory filing or a company statement, where the news is the filing.
Working rules we hold ourselves to:
We link the primary document, not the aggregator. Where a news outlet is the only place a figure appears — the eTick submission totals above, for example — we say so and name the outlet rather than dressing it up as official data.
Numbers get their reporting year and their denominator. "39.6% of adult ticks" means little without "19 of 48".
Preprints are labelled as preprints. They have not been peer reviewed and their numbers can change.
We summarise; we do not reword the source. Every entry here is written from scratch. If you want the source's own phrasing, follow the link.
If we cannot source a detail, it does not appear. That includes patient ages, locations and circumstances, which are frequently mangled as a story is retold.
Two items came to us as leads this month and did not survive checking. We list them because what fails verification is as informative as what passes.
That Dermacentor similis is "established" in southern British Columbia. The species is real and it is present. Described in 2021 from western populations previously lumped in with the American dog tick, it was confirmed in British Columbia by DNA sequencing of ticks collected from companion animals: 27 samples that had keyed out as D. variabilis turned out to be D. similis (Journal of Medical Entomology, DOI 10.1093/jme/tjae133). But established is a stronger claim than the evidence supports. Drag sampling at 33 sites across southern British Columbia in May 2022 recovered only D. andersoni, the Rocky Mountain wood tick, and no D. similis at all (Veterinary Parasitology: Regional Studies and Reports, January 2025). Ticks pulled off dogs prove the species is in the province; they do not prove a reproducing free-living population. We have written it as "confirmed present, establishment not yet demonstrated by environmental sampling."
That Public Health Ontario "added eight new risk areas for 2026." PHO's own release describes the 2026 map as reflecting "newly identified or expanded" risk areas based on 2025 data and does not give a count. We could not find the number eight in any PHO document, and a similar-looking figure circulating online refers to something different — the count of public health units classified as established Lyme-endemic. We dropped the number and described the update as PHO describes it.
Reading a tick headline critically
Four questions handle most of what goes wrong in tick coverage, and you can apply them to the entries above as well as to anything else you read.
Ticks or people? "Virus found in ticks" and "person hospitalised" are different findings. Range-expansion stories are almost always the former.
How many were tested? A percentage without a denominator is not a measurement. Two positives out of eight is not the same claim as 200 out of 800, even though both are 25%.
Did the counting method change? Nova Scotia is the cleanest example on this page: a definition change moved the reported count by a factor of six with no comparable change in underlying risk.
Is the risk where you are? Species ranges are patchy at the scale that matters to you. A finding in Buncombe County, North Carolina says nothing about Winnipeg.
Not medical advice. This log summarises published surveillance and research for general information. If you have been bitten and feel unwell, or you are unsure whether post-exposure prophylaxis applies to you, speak to a clinician — decisions about antibiotics depend on the tick species, how long it was attached, and local infection rates.
Public submissions are what generate the surveillance data on this page. In Canada, photograph the tick and upload it to eTick.ca. In the US, check whether your state runs a testing programme — TickReport accepts mail-in specimens nationally.