When should blood be drawn after a tick bite to test for encephalitis and borreliosis?

Understanding Tick-Borne Diseases

Encephalitis: A Brief Overview

Symptoms and Risks

Tick attachment carries a risk of transmitting neuroborreliosis and tick‑borne encephalitis; laboratory confirmation relies on serum antibodies whose detectability changes over time. Early identification of clinical signs guides the decision on when to obtain blood samples.

Typical manifestations that suggest infection include:

Fever, chills, malaise
Headache, neck stiffness, photophobia
Facial nerve palsy or other cranial neuropathies
Nausea, vomiting, or abdominal pain
Erythema migrans or other expanding skin lesions
Muscle or joint aches, especially in large joints

Failure to recognize these symptoms can lead to delayed diagnosis, with several consequences:

Progression to meningoencephalitis, potentially causing permanent neurological deficits
Development of chronic arthritic or cardiac involvement in Lyme disease
Increased likelihood of severe systemic illness requiring hospitalization
Reduced effectiveness of antimicrobial therapy when initiated late

Serologic testing should be performed at two intervals to capture the evolving antibody response. An initial sample taken within the first week after symptom onset establishes a baseline; a follow‑up specimen collected 2–4 weeks later detects seroconversion or rising titers. This approach compensates for the window period during which early antibodies may be absent.

«Early serologic testing may be negative; repeat testing after 2–4 weeks improves sensitivity». Timely sampling, aligned with the appearance of neurological or systemic signs, minimizes the risk of missed or late diagnosis and supports appropriate therapeutic intervention.

Pathogenesis and Transmission

Pathogenic agents transmitted by Ixodes spp. ticks include the flavivirus responsible for tick‑borne encephalitis (TBE) and the spirochete Borrelia burgdorferi, the causative organism of Lyme borreliosis. Transmission occurs during prolonged attachment; TBE virus is released from the salivary glands after at least 24 hours of feeding, whereas Borrelia spirochetes can be transferred within 12–24 hours. Both agents disseminate via the bloodstream to target organs, provoking neuroinflammation in the case of TBE and multisystemic involvement for Lyme disease.

TBE virus replicates initially in dermal cells, then spreads to regional lymph nodes and the central nervous system, where it induces neuronal injury and inflammation. Borrelia burgdorferi penetrates the skin, evades innate immunity, and migrates to joints, heart, and nervous tissue, eliciting a chronic inflammatory response. Early-stage infection is typically asymptomatic, progressing to characteristic clinical manifestations after the pathogen‑specific immune response develops.

Serologic detection relies on the appearance of specific antibodies. For TBE, IgM becomes measurable 5–7 days after symptom onset, with IgG persisting for months. For Lyme disease, IgM antibodies appear 2–4 weeks post‑exposure, while IgG seroconversion occurs after 4–6 weeks. Consequently, optimal blood sampling to assess both infections follows these intervals:

Minimum 7 days after the bite for TBE IgM detection.
At least 14 days after the bite for early Lyme IgM, extending to 4 weeks for reliable IgG.

Collecting specimens earlier than these windows yields a high likelihood of false‑negative results, whereas sampling beyond the recommended periods provides accurate serologic confirmation of exposure.

Borreliosis (Lyme Disease): A Brief Overview

Stages and Symptoms

Tick‑borne encephalitis and Lyme disease each progress through distinct clinical phases, which determine the optimal window for serologic testing.

The early phase of tick‑borne encephalitis begins 3–8 days after the bite and is characterized by nonspecific flu‑like symptoms: fever, malaise, headache, myalgia, and sometimes nausea. During this period, viral RNA may be detectable, but specific IgM antibodies typically appear after day 7, reaching peak titres around day 10–14. Drawing blood before day 7 often yields false‑negative serology.

The second, neurologic phase emerges 1–2 weeks later, with meningitis, encephalitis, or meningo‑encephalitis signs: stiff neck, photophobia, altered consciousness, focal neurological deficits, and seizures. IgG antibodies rise concurrently with IgM, persisting for years. Sampling at the onset of neurological symptoms confirms the diagnosis, but a repeat sample 2–3 weeks later clarifies seroconversion.

Lyme disease follows a biphasic pattern. The initial localized stage appears 3–30 days post‑exposure, presenting as an erythema migrans rash, accompanied by fever, chills, fatigue, arthralgia, and sometimes facial palsy. Specific anti‑Borrelia IgM antibodies become detectable around day 14, with IgG appearing 4–6 weeks after infection. Early serology performed before day 14 frequently lacks sensitivity; a second draw at 4–6 weeks improves diagnostic yield.

The disseminated stage, occurring weeks to months later, includes multiple rashes, neuroborreliosis (meningitis, radiculitis), carditis, and arthritic manifestations. IgG titres are high, and repeat testing is unnecessary unless treatment response must be monitored.

Practical timing for blood sampling

Tick‑borne encephalitis
1. First sample : day 7–10 after bite (detect IgM).
2. Second sample : day 14–21 (confirm IgG seroconversion).
Lyme disease
1. First sample : day 14–21 after bite (detect IgM).
2. Second sample : day 28–42 (detect IgG, confirm infection).

Collecting specimens within these intervals aligns testing with the appearance of disease‑specific antibodies, reducing false‑negative results and supporting accurate clinical management.

Geographic Distribution and Prevalence

Tick‑borne encephalitis (TBE) and Lyme disease exhibit distinct but overlapping geographic patterns. TBE prevalence concentrates in central and eastern Europe, the Baltic states, parts of Scandinavia, and western Russia. Lyme disease, caused by Borrelia burgdorferi, shows the widest distribution, extending across North America, most of Europe, and parts of Asia where competent Ixodes species occur.

In regions with high TBE incidence, seroprevalence among the population can exceed 10 percent, with seasonal peaks during spring and early summer when nymphal ticks are most active. Lyme disease seroprevalence commonly ranges from 5 to 20 percent in endemic areas of the United States (Northeast, Upper Midwest) and central Europe. Local surveillance data indicate that co‑infection rates may reach 15 percent in habitats supporting both pathogens.

Timing of serological sampling after a tick bite must align with pathogen‑specific seroconversion windows. For TBE, IgM antibodies typically appear 7–10 days post‑exposure, while IgG emerges after 14 days. For Lyme disease, early‑stage IgM may be detectable 3–5 days after the bite, but reliable IgG detection often requires 2–3 weeks. Consequently, optimal blood collection schedules differ by region and by the dominant pathogen:

High‑risk TBE zones: draw blood ≈ 10 days for IgM screening; repeat at ≈ 21 days for IgG confirmation.
Lyme‑endemic areas: initial sample ≈ 5 days for early‑stage IgM; follow‑up at ≈ 21 days for IgG.
Regions with both diseases: perform dual sampling at ≈ 10 days and ≈ 21 days to capture the earliest detectable antibodies for each pathogen.

Adhering to these intervals maximizes diagnostic yield, reduces false‑negative results, and supports timely clinical decision‑making.

Factors Influencing Blood Test Timing

Incubation Periods of Tick-Borne Diseases

Tick-Borne Encephalitis (TBE) Incubation

Tick‑borne encephalitis (TBE) has an incubation period that determines the earliest moment when laboratory confirmation becomes reliable. After a tick bite, the virus typically replicates locally before entering the bloodstream, a phase lasting 3–7 days. Viremia peaks during this window, after which the immune response produces detectable IgM antibodies. Consequently, serological testing performed before day 5 post‑exposure often yields false‑negative results because antibodies have not yet reached measurable levels.

Key timing considerations for blood sampling:

Days 5–7: First reliable detection of TBE‑specific IgM; suitable for initial diagnostic draw.
Days 10–14: Antibody titres increase markedly; optimal for confirming infection if earlier sample was inconclusive.
Beyond 14 days: Persistent IgM may remain; useful for retrospective diagnosis but less informative for acute phase.

For Borrelia burgdorferi, the causative agent of Lyme disease, seroconversion generally occurs later, with IgM detectable around 7–14 days and IgG appearing after 3–6 weeks. Therefore, a dual‑purpose blood draw aimed at both pathogens should be scheduled no earlier than day 7 post‑bite to capture TBE IgM while still allowing early Borrelia detection. A second sample at 2–3 weeks can confirm Borrelia seroconversion and reinforce TBE diagnosis if needed.

Lyme Borreliosis Incubation

The incubation period of Lyme borreliosis determines the earliest moment when serological markers become detectable. After a tick attachment, Borrelia burgdorferi typically requires 5 to 14 days before specific IgM antibodies appear in peripheral blood; IgG seroconversion usually follows within 3 to 6 weeks. Early-stage disease may be missed if sampling occurs before the IgM response, leading to false‑negative results.

Encephalitic involvement, such as Lyme neuroborreliosis, often manifests later than the initial cutaneous stage. Cerebrospinal fluid analysis becomes informative after neurological symptoms develop, commonly 2 to 4 weeks post‑exposure. However, serum testing for intrathecal antibody production can be performed concurrently with peripheral blood sampling once the IgG response is established.

Practical timing recommendations:

Day 0‑4 : blood draw unlikely to yield positive serology; reserve for baseline if immediate evaluation is required.
Day 5‑14 : IgM antibodies may be detectable; consider sampling if early systemic signs are present.
Day 15‑42 : both IgM and IgG antibodies generally present; optimal window for reliable serological diagnosis of Lyme disease.
Beyond 6 weeks : IgG persists; useful for confirming past infection or assessing treatment response.

Aligning specimen collection with these intervals maximizes diagnostic yield for both Lyme borreliosis and associated encephalitic complications.«»

Antibody Production and Detection

IgM and IgG Response in TBE

The serological pattern of tick‑borne encephalitis (TBE) is defined by the sequential appearance of immunoglobulins.

«IgM» becomes detectable 7–14 days after the tick bite, reaches a maximum around the third–fourth week, and declines to low or undetectable levels within two to three months.

«IgG» appears slightly later, typically 14–21 days post‑exposure, rises steadily, and may persist for years, providing evidence of past infection.

For laboratory confirmation, two blood samples are recommended:

first specimen collected 2–3 weeks after the bite, when «IgM» is likely to be present;
second specimen taken 4–6 weeks after the bite, to verify seroconversion or the emergence of «IgG».

If the initial draw occurs earlier than the 7‑day window, both antibodies may be absent, leading to false‑negative results. Re‑testing after the recommended interval resolves this limitation and distinguishes acute TBE from prior exposure.

Seroconversion in Lyme Disease

Seroconversion refers to the appearance of specific antibodies in the bloodstream following infection with Borrelia burgdorferi. Detectable IgM antibodies typically emerge 2–4 weeks after exposure; IgG antibodies become reliably measurable 4–6 weeks post‑exposure and persist for months to years. Early serologic testing, performed before the IgM window closes, yields a high false‑negative rate because antibody concentrations remain below assay detection thresholds.

The timing of blood collection for diagnostic evaluation of tick‑borne encephalitis and Lyme disease must align with the seroconversion curve. Drawing samples too early can miss the humoral response; drawing too late may obscure the acute phase and complicate interpretation of IgM versus IgG patterns.

Recommended intervals for specimen collection:

First sample: 3 weeks after the bite, to capture emerging IgM if infection is present.
Second sample: 6 weeks after the bite, to confirm IgG seroconversion and differentiate recent from past exposure.
Optional follow‑up: 12 weeks post‑exposure, for cases with ambiguous initial results or persistent clinical suspicion.

Testing performed within these windows maximizes sensitivity for both acute encephalitic and borreliosis serology, facilitating accurate diagnosis and timely therapeutic decisions. «Early detection of seroconversion improves clinical outcomes by enabling prompt antimicrobial intervention».

Type of Test and Its Sensitivity

PCR Testing for Early Detection

PCR testing provides the most rapid means of confirming a tick‑borne infection during the initial viremic period. For tick‑borne encephalitis, viral RNA appears in peripheral blood within the first 3‑7 days after the bite. Drawing blood within this window maximizes the probability of a positive PCR result and enables prompt antiviral management. Beyond the first week, RNA concentrations fall below detectable levels, rendering PCR unreliable.

For Lyme disease caused by Borrelia burgdorferi, PCR sensitivity in whole blood is low throughout the course of infection. Detectable spirochetal DNA is most likely in skin lesions (erythema migrans) or cerebrospinal fluid during later stages. Consequently, blood PCR is not the preferred diagnostic tool; serologic testing after 2‑3 weeks remains the standard approach.

Key points for early PCR detection after a tick bite:

Tick‑borne encephalitis: collect blood ≤ 7 days post‑exposure; prioritize the first 3 days for highest yield.
Lyme disease: blood PCR generally uninformative; consider skin biopsy or CSF PCR if neurological involvement is suspected.
Timing influences assay sensitivity more than specimen volume or extraction method.

Optimal sampling strategy aligns the collection moment with the pathogen’s replication kinetics, ensuring that molecular diagnostics deliver actionable results.

ELISA and Western Blot for Antibody Detection

ELISA assays detect IgM and IgG antibodies against Borrelia burgdorferi and tick‑borne encephalitis virus. Antibody levels typically become measurable 2 – 4 weeks after exposure; testing earlier yields a high rate of false‑negative results. A negative ELISA performed within this window does not exclude infection and should be repeated if clinical suspicion persists.

Western blot analysis serves as a confirmatory test following a positive ELISA. Specific protein bands appear reliably after 4 – 6 weeks, providing greater specificity for both Lyme disease and encephalitis serology. Conducting Western blot before this period may miss low‑titer antibodies and reduce diagnostic accuracy.

Practical timing recommendations

Initial ELISA: 14 – 28 days post‑bite.
Repeat ELISA (if first test negative and symptoms continue): after additional 7 – 14 days.
Western blot confirmation: ≥ 28 days after exposure, preferably 35 – 42 days.

Recommended Blood Draw Timelines

Testing for Tick-Borne Encephalitis

Initial Testing After Exposure

After a tick attachment, the first laboratory assessment should focus on detecting early immune responses to the most common pathogens transmitted by Ixodes species. For tick‑borne encephalitis, serum IgM antibodies become measurable approximately 7–10 days after the bite; for Lyme disease, IgM against Borrelia burgdorferi appears within 2–4 weeks, while IgG may be detectable later. Drawing blood too early can yield false‑negative results because antibody concentrations have not yet reached the assay’s detection threshold.

Recommended timing for the initial blood sample:

Day 7–10 post‑exposure: collect serum for tick‑borne encephalitis IgM testing; consider parallel polymerase chain reaction if neurological symptoms are present.
Day 14–21 post‑exposure: obtain serum for Lyme disease IgM ELISA; if clinical suspicion persists, follow with Western blot confirmation.
If the patient presents with symptoms before the above windows, prioritize nucleic‑acid amplification tests on cerebrospinal fluid or skin biopsy, acknowledging limited sensitivity in early stages.

Interpretation of results must consider the incubation period of each infection. A negative serology within the early window does not exclude disease; repeat testing after 3–4 weeks is advisable to capture seroconversion. Immediate treatment decisions should rely on clinical presentation and exposure risk, not solely on initial serologic findings.

Follow-up Testing Protocols

After a tick attachment, clinicians must schedule serologic examinations to confirm or exclude infection with Borrelia spp. and tick‑borne encephalitis (TBE) virus. The initial blood draw establishes a baseline for antibody status and should occur as early as feasible, preferably within 7–14 days post‑exposure.

Subsequent specimens are required to detect seroconversion or rising titers. Recommended intervals are:

4–6 weeks after the bite: captures early IgM response for both pathogens.
8–12 weeks post‑exposure: identifies transition to IgG dominance, confirming established infection.
3 months, if earlier samples remain negative but clinical suspicion persists: ensures late seroconversion is not missed.

Interpretation follows standard serologic criteria:

Presence of IgM without IgG at 4–6 weeks suggests recent infection.
Emergence of IgG, with or without persistent IgM, indicates ongoing or past infection.
A four‑fold rise in antibody titer between baseline and follow‑up confirms recent exposure.

Special circumstances modify timing:

Immunocompromised patients may require earlier repeat testing, as antibody production can be delayed.
Prophylactic antibiotics administered within 72 hours of removal may suppress early serologic signals, warranting a later draw at 8–12 weeks.
Neurological symptoms consistent with encephalitis demand cerebrospinal fluid analysis in addition to serum testing, regardless of serologic schedule.

Adherence to these intervals facilitates accurate diagnosis, guides therapeutic decisions, and reduces the risk of missed or delayed treatment for both «Lyme disease» and «tick‑borne encephalitis».

Testing for Borreliosis (Lyme Disease)

Early Stage Testing

Early stage testing after a tick bite focuses on detecting the initial immune response to tick‑borne encephalitis viruses and Borrelia spirochetes. Antibody production typically begins 7–14 days post‑exposure; however, detectable levels often require at least 2 weeks. Consequently, drawing blood before this interval yields a high probability of false‑negative serology.

For encephalitis viruses, molecular methods such as reverse‑transcriptase PCR on serum or cerebrospinal fluid can identify viral RNA within the first days after symptom onset. Serologic assays (IgM, IgG) become reliable after the second week. In Lyme disease, early disseminated infection may produce a transient bacteremia detectable by PCR, but standard two‑tier serology (ELISA followed by Western blot) achieves sufficient sensitivity only after 2–4 weeks.

Recommended timing for the first blood sample:

Minimum 14 days after the bite for serologic panels targeting both pathogens.
If neurological symptoms appear earlier, collect an additional sample for PCR and consider lumbar puncture for CSF analysis.
Repeat serology at 4–6 weeks if the initial test is negative and clinical suspicion persists.

Interpretation must consider the window period: a negative result obtained before the immune response matures does not exclude infection. Follow‑up testing aligns the diagnostic window with the kinetics of antibody development and pathogen detection.

Later Stage Testing for Confirmation

Later‑stage serologic evaluation aims to confirm infection after the initial immune response has developed. Blood should be collected when antibodies become reliably detectable, typically 4 to 6 weeks post‑exposure. At this point, IgM titres rise for both tick‑borne encephalitis virus and Borrelia burgdorferi, while IgG seroconversion indicates ongoing or past infection.

Key laboratory methods for confirmation include:

Enzyme‑linked immunosorbent assay (ELISA) for IgM and IgG against tick‑borne encephalitis virus antigens.
Western blot or immunoblot for Borrelia‑specific IgM/IgG, providing species‑level resolution.
Real‑time polymerase chain reaction (PCR) on serum or cerebrospinal fluid, useful when antibody responses are delayed or atypical.

If initial testing occurs earlier than the recommended interval, repeat sampling after the 4‑week mark is advised to capture seroconversion. Persistent IgM without IgG conversion beyond 8 weeks may suggest false‑positive results, prompting confirmatory testing with a different assay format.

Interpretation relies on established cutoff values and the clinical picture. Positive IgM with compatible symptoms supports recent infection; concurrent IgG positivity reinforces diagnosis and guides therapeutic decisions.

Important Considerations and Clinical Guidance

Risk Factors for Infection

Tick Species and Endemic Areas

Ixodes ricinus, the most common European tick, transmits both tick‑borne encephalitis (TBE) virus and Borrelia burgdorferi. Its distribution spans Central and Northern Europe, extending into the Baltic states and parts of the Balkans. Dermacentor reticulatus, prevalent in Eastern Europe and the Caucasus, is a secondary vector for TBE and can carry Borrelia species.

In North America, Ixodes scapularis (eastern black‑legged tick) and Ixodes pacificus (western black‑legged tick) are primary carriers of Borrelia burgdorferi. Ixodes scapularis also transmits Powassan virus, a cause of encephalitis, and is found along the Atlantic seaboard and the Great Lakes region. Ixodes pacificus occupies the western United States, from California to Washington.

Other notable vectors include:

Haemaphysalis longicornis – emerging in East Asia and recently detected in the United States; potential carrier of Borrelia and viral agents.
Hyalomma marginatum – endemic to the Mediterranean basin and parts of the Middle East; associated with Crimean‑Congo hemorrhagic fever but also capable of harboring encephalitic viruses.

Understanding the geographic range of each species guides clinicians in assessing exposure risk and selecting appropriate serologic testing windows after a bite.

Duration of Tick Attachment

The risk of pathogen transmission increases sharply after the tick remains attached for a certain period. Borrelia burgdorferi typically requires at least 36 hours of attachment to be transferred, while the virus that causes tick‑borne encephalitis can be transmitted after 24–48 hours. Consequently, the duration of attachment provides a practical indicator for when serologic testing becomes reliable.

For encephalitis testing, blood should be drawn no earlier than two weeks after the bite if the tick was attached for more than 24 hours. At this point, specific IgM antibodies are usually detectable, and a repeat sample after four weeks confirms seroconversion. Testing before this interval often yields false‑negative results because the immune response has not yet matured.

For Lyme disease, the recommended sampling schedule is:

First sample: 3–4 weeks post‑bite when the tick was attached ≥36 hours; IgM antibodies are expected.
Second sample: 6–8 weeks after the bite to detect IgG seroconversion and to verify persistence of antibodies.

«Longer attachment, higher probability of detectable antibodies» summarizes the relationship between tick‑attachment duration and the optimal timing for blood collection.

Symptom Monitoring and Clinical Correlation

Differentiating Early Symptoms

Early clinical presentation after a tick attachment often includes overlapping signs that can obscure the distinction between viral encephalitis and spirochetal infection. Accurate identification of symptom patterns directs the timing of serologic sampling, reducing false‑negative results.

«Encephalitis» typically manifests with sudden fever, severe headache, photophobia, altered mental status, and neck rigidity. Neurological deficits such as focal weakness or seizures may appear within days of symptom onset. In contrast, «borreliosis» (Lyme disease) begins with localized erythema migrans, often accompanied by fatigue, myalgia, arthralgia, and mild fever. Flu‑like malaise may precede the rash, and neurologic involvement (cranial nerve palsy, meningitis) generally emerges weeks after the bite.

For encephalitis, antibody detection in serum or cerebrospinal fluid becomes reliable after 7–14 days from the first neurological sign; earlier specimens frequently lack detectable titers. For Lyme disease, IgM antibodies appear around 2–3 weeks post‑exposure, while IgG seroconversion stabilizes between 4–6 weeks. Consequently, blood collection for encephalitis testing should be scheduled no sooner than one week after neurological symptoms, whereas sampling for Lyme serology is optimal at the three‑week mark, with a repeat at six weeks if the initial result is negative and clinical suspicion persists.

When to Seek Medical Attention

Blood‑borne testing after a tick encounter depends on the pathogen’s immune response timeline. For tick‑borne encephalitis, specific IgM antibodies typically become detectable within one to two weeks post‑exposure; drawing blood before this window yields a high false‑negative rate. For Lyme disease, serologic conversion usually occurs after two to three weeks, although early treatment decisions often rely on clinical presentation rather than laboratory confirmation.

Seek professional evaluation promptly if any of the following appear:

High fever persisting beyond 48 hours
Severe headache, neck stiffness, or photophobia
Rapidly developing facial weakness or paralysis
Joint swelling, especially in the knees, accompanied by pain
Unexplained fatigue, muscle aches, or malaise lasting more than a week
Rash expanding beyond the initial bite site, particularly if it forms a target‑like pattern

Immediate assessment is also warranted after a known tick bite in individuals with compromised immunity, pregnant women, or children under ten years of age. In such cases, clinicians may order serologic testing earlier than standard intervals to guide prophylactic therapy.

If symptoms develop after the typical seroconversion periods, blood sampling should be scheduled at least two weeks post‑bite for encephalitis markers and three weeks for Lyme disease antibodies. Delayed testing beyond four weeks may still be informative but should be combined with a thorough clinical review.

Timely medical attention reduces the risk of severe neurological complications and facilitates appropriate antimicrobial or antiviral interventions.

Prophylactic Treatment and Its Impact on Testing

Post-Exposure Prophylaxis for Lyme Disease

Post‑exposure prophylaxis (PEP) for Lyme disease is administered immediately after a confirmed or highly suspicious tick bite when the attached tick is identified as an Ixodes species and has been attached for ≥ 36 hours. A single dose of doxycycline 200 mg orally, taken within 72 hours of removal, reduces the risk of early Lyme infection by approximately 87 %. The regimen is contraindicated in pregnant or lactating women, children < 8 years, and patients with doxycycline hypersensitivity; alternative agents such as amoxicillin 2 g single dose may be considered.

PEP influences serological testing. Antibiotic exposure can suppress the development of detectable antibodies, potentially yielding false‑negative results if blood is drawn too soon after treatment. Current recommendations advise:

If PEP is given, collect the first serum sample at least 2 weeks after the dose to allow IgM/IgG seroconversion.
For patients in whom PEP is not administered, the initial draw may occur 7–10 days post‑exposure, aligning with the earliest expected antibody rise for tick‑borne encephalitis and Lyme disease.
A convalescent sample should be obtained 4–6 weeks after the initial draw to confirm seroconversion or to detect rising titres.

Laboratory interpretation follows established two‑tier testing for Lyme disease (ELISA screening followed by immunoblot confirmation) and IgM/IgG ELISA for tick‑borne encephalitis. Timing of specimen collection is critical to avoid misdiagnosis caused by premature testing or antibiotic‑induced seronegativity.

Key points for clinicians:

Initiate doxycycline promptly when criteria are met; document the exact time of administration.
Schedule the first blood draw no earlier than 14 days post‑PEP to ensure reliable antibody detection.
Arrange a follow‑up sample 4–6 weeks later for definitive serologic assessment.
Educate patients about signs of systemic illness that warrant earlier evaluation, regardless of prophylaxis status.

Vaccination for Tick-Borne Encephalitis

Vaccination against tick‑borne encephalitis (TBE) provides active immunity that reduces the probability of severe neurological disease following a tick bite. The vaccine is administered in a primary series of three doses, typically at 0, 1–3 months, and 5–12 months, followed by booster injections every 3–5 years depending on age and risk exposure.

Serological testing after a tick bite must consider vaccination status. In vaccinated individuals, the presence of TBE‑specific IgG reflects immunization rather than recent infection; therefore, IgM detection is essential for diagnosing acute disease. Blood sampling for IgM is most reliable when performed at least 7 days after the bite, as the immune response usually becomes detectable between days 5 and 10. Earlier collection may yield false‑negative results, especially in partially immunized patients.

Key points for clinicians:

Collect blood no earlier than day 7 post‑exposure to capture IgM seroconversion.
In vaccinated persons, interpret IgG results as vaccine‑induced; focus on IgM for acute infection.
For Lyme disease serology, obtain a sample at day 14–21, when Borrelia‑specific antibodies are more likely to be present.
Booster vaccination within the past year does not alter the recommended sampling window for TBE testing.
Document vaccination dates to aid laboratory interpretation and avoid misclassification of immune status.

«Vaccination is the most effective preventive measure against tick‑borne encephalitis», and proper timing of blood collection ensures accurate laboratory diagnosis while maintaining the protective benefits of immunization.