• Tick-borne disease is fundamentally a clinical diagnosis confirmed (or not) by lab evidence, not a lab diagnosis on its own.
• Standard ELISA is only ~53% sensitive; the standard 2-tier ELISA + Western blot combination is ~57% overall; PCR on blood is under 30% sensitive.
• The sicker a person is, the weaker their serologic response tends to be — meaning the most sensitive tests are needed most in the hardest, most chronic cases.
• The characteristic “bull’s-eye” erythema migrans rash is often cited as appearing in roughly 25–40% of cases at the acute stage, and in some paediatric studies in as few as a third — it should never be treated as a reliable gatekeeper for testing or treatment.

• The World Health Organization estimated around 85,000 cases annually across Europe as of 2006, while explicitly flagging that figure as a substantial underestimate.
• In the US, roughly 300,000 cases are diagnosed each year according to CDC estimates.
• Lab-confirmed cases in England and Wales rose from 268 in 2001 to 959 in 2011 — but Lyme is not a notifiable disease in the UK, so true new-case numbers are essentially unknown.
• Public Health England’s own estimate sits around 3,000 cases a year, while patient-support charities such as Lyme Disease UK suggest the real figure could run into the tens of thousands.

• More than 22–37 Borrelia species exist worldwide; large commercial labs typically test only for B. burgdorferi B31, a single tick-derived lab strain.
• Separate from the “Lyme-group” species (afzelii, garinii, spielmanii, bavariensis, mayonii) is a distinct group of tick-borne relapsing fever (TBRF) species (hermsii, miyamotoi, turicatae, and others) that standard Lyme panels are not designed to catch.
• A 2018 IGeneX review of over 10,000 samples found Lyme Borrelia (sensu lato) positive in 32.1% and TBRF Borrelia positive in 27.7% — reference-lab samples skew toward more chronically ill patients, so these figures likely overstate general-population rates, but they illustrate how much a single-strain panel can miss.

• Common myths: that TBRF is rare in the US/UK, has an unmistakable clinical picture, and is only spread by soft ticks. All false — TBRF is found widely, can present exactly like Lyme, and hard-bodied (Ixodes) ticks also carry some species.
• The “classic” pattern — recurring ~3-day febrile episodes with a dramatic chill/flush cycle — is often absent; many patients present just like ordinary Lyme instead.
• In cohorts of patients with suspected Lyme, 29–38% were antibody-positive for TBRF species when tested — none showed the classic acute presentation.

Indirect tests (look for the body’s immune response):

• Not recommended alone IFA / ELISA — single species/strain only; poor sensitivity and specificity; not useful in early (<6 week) or chronic disease.
• Not recommended alone Western blot — detects only one species at a time; band intensity depends on both antigen and antibody quantity, so results are inconsistent. Poor sensitivity and specificity together, plus narrow species coverage.
• Best available Recombinant-antigen assays (e.g. IGeneX ImmunoBlot, LSA, BCA, AcuDart) — lab-engineered antigens chosen for specificity and multi-species/strain coverage. Most sensitive serologies currently available; usable at all disease stages, including while on treatment; positives reported from around 2 weeks after a bite.
• T-cell mitogen stimulation assay — measures T-cell activation rather than antibody, so it can be positive in seronegative patients. Useful very early and very late in chronic illness, and in patients with immunoglobulin deficiencies.

Direct tests (look for the pathogen itself):

• FISH (fluorescent in-situ hybridization) — directly visualizes the organism on a blood smear, including within biofilms. Highly specific; reflects current active infection. Most useful very early and again very late in chronic illness as immunity declines.
• PCR — detects pathogen DNA; highly specific but poorly sensitive in blood due to low organism numbers. More useful on solid-tissue biopsies than blood alone.
• Culture-enhanced PCR (cePCR) — sample is cultured for around 2 weeks before PCR, substantially boosting sensitivity over standard PCR.
• Urine antigen capture — detects Borrelia antigens shed into urine during active infection (Lyme-group only). Testing on 3 separate days, ideally during a symptom flare, improves yield. Useful when blood draws are impractical, and is one of the few direct tests that can be run while on treatment.

• CDC two-tier testing pairs a screening ELISA (tier 1) with a confirmatory Western blot (tier 2) — but the tier-1 ELISA has historically been only around 50% sensitive on its own.
• The CDC’s older Western blot criteria required 5 of 10 specified IgG bands; several of those bands are not Lyme-specific (raising false-positive risk), while two genuinely Lyme-specific bands were historically excluded (raising false-negative risk). It also covered only one strain of one species.
• IGeneX’s Lyme IgG ImmunoBlot received FDA clearance as a genuine two-tier test, includes the previously-excluded specific bands, and is multi-species capable with reported sensitivity above 90%.
• AcuDart — an at-home/in-office fingerstick screening kit covering Lyme, TBRF, Babesia, and Bartonella in one result, with positives confirmable via a full ImmunoBlot.

• Early (<4 weeks / Stage 1): urine antigen capture can be positive as soon as symptoms start; ImmunoBlot serology starts turning positive around week 2; T-cell stimulation assays can respond in under 2 weeks; culture-enhanced PCR is likely useful soon after onset but results take around 3 weeks.
• Disseminated, not yet chronic (Stage 2, roughly 3–6 months): recombinant serology is generally the first choice; urine antigen capture is still useful, best during a flare; direct blood tests are generally less sensitive at this stage, especially on treatment.
• Chronic (Stage 3, 6–12+ months): all blood testing loses sensitivity as immunity is depressed and fewer organisms circulate in blood. Combining methods — recombinant serology plus T-cell stimulation, FISH, culture-enhanced PCR, and urine antigen capture where applicable — gives the best overall picture.

• More than 45 Bartonella species are known to science; commercial labs typically test only for B. henselae and B. quintana.
• A negative standard panel therefore does not rule out infection with a less common species — B. elizabethae, B. vinsonii, B. koehlerae, B. washoensis, B. rochalimae and others also infect humans via fleas, ticks, and other vectors.
• A 2018 IGeneX review of over 10,000 reference-lab samples found Bartonella positive in 19.1% of samples tested, with co-infection alongside Borrelia and/or Babesia common.

• FISH (direct visualization of the organism on a blood smear, including within biofilms) and culture-based PCR (e.g. via specialist labs such as Galaxy Diagnostics) are currently the most useful direct tests.
• Unlike Borrelia or Babesia, the timing of peak Bartonella pathogen load in blood is not well established — so a single negative direct test carries less weight than it would for the other two pathogens.
• Standard antibody serology (IFA/ELISA) for Bartonella suffers the same single-species, single-strain limitations described for Borrelia above.

• Striae (stretch-mark-like lines) that don’t follow normal dermal lines and blanch when pressed.
• Migratory neuropathy or muscle fasciculations.
• Rage/aggression episodes, or a constant daily “flare” pattern to symptoms.
• Eye findings — uveitis, conjunctivitis with granulomatous nodules, or neuroretinitis.

• More than 100 Babesia species exist globally. B. microti is the main species tested for in the US and UK, but B. duncani, B. odocoilei (which cross-reacts serologically with duncani), MO-1, and others also cause human illness and are missed by standard microti-only panels.
• A 2018 IGeneX review of over 10,000 reference-lab samples found Babesia positive in 37.3% of samples tested — the highest of the three pathogens in that dataset, though again likely skewed toward more chronically ill patients.
• B. odocoilei is carried by white-tailed deer (whose population has roughly doubled since 1950) and infects an estimated 10–30% of deer ticks in the US and Canada — comparable to Lyme’s roughly 30% infection rate — yet it was only confirmed in humans with babesiosis symptoms in 2021.
• B. duncani antibodies are found in humans across the US and Canada at roughly three times the rate of B. microti antibodies, despite B. duncani itself being largely confined to the US West Coast and not carried by deer ticks — one proposed explanation is that much of this reactivity actually reflects cross-reaction with B. odocoilei.
• Acute babesiosis (fever, hemolysis, a positive blood smear) is the form recognised by mainstream infectious-disease guidance, and is rare — mainly in asplenic or immunocompromised patients. Chronic babesiosis is proposed to be common in immunocompetent people but is not currently recognised by that same guidance, has no fever, and typically shows negative blood smears, FISH and PCR.

• FISH is particularly well suited to Babesia — pathogen load in blood is highest very early in infection (before immunity develops) and again late in chronic illness, so FISH sensitivity tracks both of those windows.
• A direct blood smear can also catch acute infection when parasite load is high.
• Antibody serology and PCR carry the same general limitations described for Borrelia above — most useful early, less reliable once infection is established and chronic.
• Routine bloods (CBC, CMP, ESR, CRP) are usually normal in chronic babesiosis, though a low CD57 (NK cell) count or elevated C4a is sometimes seen.
• For B. odocoilei specifically: IGeneX offers a FISH test for active infection, a B. duncani antibody test, and a newer Babesia immunoblot — a Genus-only IgG/IgM pattern (without species-specific bands) is read as suggestive of B. odocoilei. TLab offers a research-only 18s rRNA FISH test for B. odocoilei on venous blood, with fair sensitivity. There is no dedicated B. odocoilei antibody test at this time.
• Because chronic B. odocoilei is proposed to sequester in microvascular “nests” rather than circulate freely, all of the above direct tests can be negative despite genuine infection — Lindner (ILADS 2022) proposes that a diagnostic trial of atovaquone and/or other antimalarials, guided by clinical judgement, is the most reliable way to confirm or exclude it in a chronically ill patient with a plausible history.

• Unrelenting headache or head pressure.
• Air hunger and dry cough.
• Night sweats.
• Rib or bone pain.
• Dysautonomia (blood pressure/heart rate regulation problems).
• Severe exertional intolerance — energy in the morning that crashes rapidly with activity and requires rest to recover — proposed by Lindner as a hallmark worth treating as babesiosis until proven otherwise.

• Any deer tick bite or exposure history — Lindner notes this applies to essentially everyone in an endemic area, given how common infected ticks are.
• An initial flu-like illness after a bite is a supportive clue but is described as rare in this chronic picture, so its absence doesn’t rule anything out.
• Symptom improvement or worsening tracking with hormones, medications, herbs, supplements, antibiotics, or activity level — anything that shifts immune function or affects the parasites directly.
• Interminable herxing (worsening reaction to treatment) while being treated for Lyme or Bartonella specifically.
• Intolerance of antimalarial medications.