What tests should be done for a child after a tick bite?

Initial Actions After a Tick Bite

Removing the Tick Safely

Tools and Techniques

When a child presents after a tick attachment, clinicians rely on specific diagnostic instruments to confirm or exclude tick‑borne infections. Immediate assessment includes a thorough visual inspection of the bite site, using magnifying lenses or dermatoscopes to identify attached mouthparts and any erythema migrans lesions. If the tick is still attached, fine‑point tweezers designed for tick removal reduce tissue trauma and prevent mouthpart fragmentation.

Laboratory evaluation employs the following techniques:

Enzyme‑linked immunosorbent assay (ELISA) for detection of antibodies against Borrelia burgdorferi and other common pathogens.
Immunoblot (Western blot) performed when ELISA yields a positive or equivocal result, providing confirmatory specificity.
Polymerase chain reaction (PCR) applied to whole‑blood samples, skin biopsies, or tick tissue to identify bacterial DNA, especially in early infection when serology may be negative.
Complete blood count with differential to reveal leukocytosis, thrombocytopenia, or anemia associated with systemic involvement.
Liver function panel and serum creatinine to monitor organ impact in severe cases.

Imaging modalities are reserved for complications; ultrasound can assess joint effusions, while magnetic resonance imaging (MRI) identifies central nervous system inflammation when neurological signs appear. Each tool contributes to a structured diagnostic pathway, enabling prompt treatment decisions and minimizing long‑term sequelae.

Post-Removal Disinfection

After a tick is removed from a child’s skin, thorough disinfection is essential to minimize the risk of bacterial infection and to prepare the site for any subsequent medical evaluation. The procedure should begin immediately, using a clean, disposable instrument to grasp the tick by the mouthparts and pull straight upward with steady pressure. Once the tick is detached, follow these steps:

Clean the bite area with an antiseptic solution such as 70 % isopropyl alcohol or a povidone‑iodine preparation. Apply the solution with a sterile gauze pad, moving in a circular motion for at least 30 seconds.
Allow the skin to dry naturally; do not cover the area with adhesive bandages unless bleeding occurs.
If the child’s skin is sensitive, a mild chlorhexidine solution (0.5 % concentration) may be used as an alternative, ensuring no irritation develops.
Document the time of removal, the location of the bite, and the type of antiseptic applied. This record assists healthcare providers when ordering the appropriate laboratory examinations.

For children with known allergies to iodine or alcohol, substitute with a non‑irritating antiseptic such as hydrogen peroxide (3 % solution) applied briefly, then rinse with sterile water. After disinfection, monitor the site for signs of erythema, swelling, or pus formation. Any such changes warrant prompt medical assessment and may influence the selection of serological or molecular tests to detect tick‑borne pathogens.

Monitoring the Bite Area

Early Signs of Infection

A child who has been bitten by a tick should be observed for clinical changes that suggest the onset of infection. Early manifestations often appear within days of the bite and guide the decision to order diagnostic studies.

Redness or swelling that expands beyond the bite site
Fever exceeding 38 °C (100.4 °F)
Headache or neck stiffness
Muscle aches or joint pain, especially if asymmetric
Fatigue or irritability disproportionate to the child’s usual behavior
Nausea, vomiting, or abdominal discomfort
A rash that is not the classic “bull’s‑eye” pattern, such as a maculopapular eruption or petechiae

The appearance of any of these signs warrants prompt laboratory evaluation, typically including a complete blood count, inflammatory markers (C‑reactive protein, erythrocyte sedimentation rate), and serologic testing for tick‑borne pathogens. In regions where Lyme disease is prevalent, an initial enzyme‑linked immunosorbent assay followed by a confirmatory Western blot is standard. If neurological symptoms are present, lumbar puncture and polymerase chain reaction analysis should be considered.

Immediate medical assessment is essential; delay increases the risk of systemic involvement and complicates treatment. Parents should report the onset, duration, and progression of each symptom to facilitate targeted testing and timely therapy.

Allergic Reactions

Tick bites may trigger IgE‑mediated or non‑IgE‑mediated hypersensitivity; clinicians must incorporate allergy assessment into the post‑exposure workup for children.

For acute urticaria, angio‑edema, or anaphylaxis occurring within minutes to hours, the following investigations are indicated:

Serum tryptase measured 30 minutes–2 hours after symptom onset to confirm mast‑cell activation.
Specific IgE assay for tick saliva antigens, if commercially available, to identify sensitization.
Complete blood count with differential to detect eosinophilia, which can support an allergic etiology.

When symptoms develop days to weeks after the bite—such as a serum‑sickness‑like rash, arthralgia, or prolonged pruritus—diagnostic steps include:

Repeat eosinophil count to evaluate delayed allergic response.
Serum IgE quantification to assess overall atopic status.
Skin prick or intradermal testing with standardized tick extracts, performed under controlled conditions, to verify delayed hypersensitivity.

All results should be interpreted in conjunction with a detailed clinical history, including prior atopic disease and exposure timeline. Positive allergy markers warrant counseling on avoidance strategies, prescription of antihistamines or mast‑cell stabilizers, and a clear emergency plan for future bites.

Understanding Potential Risks

Common Tick-Borne Diseases in Children

Lyme Disease

After a tick bite, a pediatric clinician must determine whether Borrelia burgdorferi infection is present. The first step is a thorough physical examination, focusing on the characteristic expanding rash, joint swelling, and neurologic signs. Laboratory evaluation follows a defined sequence.

Serologic testing: Perform an enzyme‑linked immunosorbent assay (ELISA) to detect IgM and IgG antibodies. If the ELISA result is positive or equivocal, confirm with a Western blot using CDC‑recommended criteria. Antibody production typically becomes detectable two to four weeks after exposure; testing earlier may yield false‑negative results.
Polymerase chain reaction (PCR): Reserve for specimens from synovial fluid, cerebrospinal fluid, or skin biopsies when serology is inconclusive but clinical suspicion remains high. PCR directly detects Borrelia DNA and is most useful in disseminated disease.
Complete blood count (CBC) and differential: Identify leukocytosis or lymphocytosis that may accompany early infection. Although nonspecific, these values help assess overall inflammatory response.
Comprehensive metabolic panel: Evaluate hepatic transaminases and renal function, which can be altered in systemic Lyme disease.
Cerebrospinal fluid analysis: Indicated when neurologic symptoms such as facial palsy, meningitis, or radiculitis appear. Analyze cell count, protein, glucose, and perform Lyme PCR and antibody testing on CSF.
Joint fluid analysis: When arthritis is present, aspirate the joint for cell count, crystal examination, and PCR for Borrelia. Culture is rarely performed due to low sensitivity.

Testing should be timed according to symptom onset. If erythema migrans is present, immediate empirical antibiotic therapy may be started without waiting for serology, but baseline labs remain advisable to document organ function before treatment. Follow‑up serology at six to eight weeks can confirm seroconversion in cases where initial tests were negative but clinical suspicion persists.

Anaplasmosis

Anaplasmosis should be considered in any child who has been bitten by a tick and presents with fever, headache, or malaise. Laboratory evaluation begins with a complete blood count; leukopenia and thrombocytopenia are common findings. Liver function tests often reveal mild elevations in transaminases, supporting the diagnosis.

Specific diagnostic methods include:

Polymerase chain reaction (PCR) targeting Anaplasma phagocytophilum DNA in whole blood; PCR provides the most rapid and sensitive confirmation during the acute phase.
Indirect immunofluorescence assay (IFA) for IgM and IgG antibodies; a four‑fold rise in titer between acute and convalescent samples confirms infection, although serology may be negative early.
Peripheral blood smear examined for intracytoplasmic morulae within neutrophils; useful when performed by an experienced laboratory, but sensitivity is limited.

If initial tests are inconclusive and clinical suspicion remains high, repeat PCR or serology after 7–10 days is recommended. These investigations, combined with a thorough exposure history, allow timely identification of Anaplasma infection and appropriate antimicrobial therapy.

Babesiosis

A tick bite can introduce Babesia parasites, which cause babesiosis and may lead to hemolytic anemia in children. Prompt laboratory evaluation is essential because clinical signs often overlap with other tick‑borne diseases.

Complete blood count with differential: detects anemia, thrombocytopenia, and leukopenia.
Peripheral blood smear (Giemsa‑stained): visualizes intra‑erythrocytic ring forms and Maltese‑cross tetrads; definitive for active infection.
Polymerase chain reaction (PCR) for Babesia DNA: high sensitivity, confirms low‑level parasitemia when smear is negative.
Indirect immunofluorescence assay (IFA) or enzyme‑linked immunosorbent assay (ELISA): identifies IgM and IgG antibodies, indicating recent or past exposure.
Serum chemistry panel: assesses bilirubin, lactate dehydrogenase, and haptoglobin to evaluate hemolysis severity.

Interpretation of results guides management. Anemia with elevated bilirubin and visible parasites on smear confirms active disease; a negative smear but positive PCR suggests early infection; serology alone does not differentiate active from resolved infection. If initial testing is negative yet the child exhibits fever, fatigue, or laboratory evidence of hemolysis, repeat smear and PCR after 48–72 hours. Ongoing monitoring of hemoglobin and parasitemia levels during therapy ensures adequate response and informs duration of treatment.

Rocky Mountain Spotted Fever (RMSF)

After a tick bite, clinicians must assess the possibility of Rocky Mountain Spotted Fever, a rickettsial infection that can progress rapidly in children. Prompt laboratory evaluation is essential for confirming the diagnosis and guiding therapy.

Key investigations include:

Polymerase‑chain‑reaction assay on whole blood to detect Rickettsia rickettsii DNA; most reliable within the first few days of illness.
Acute‑phase serology (IgM and IgG) for spotted‑fever group rickettsiae; a single‑sample titer of ≥1:256 supports infection, but paired samples 2‑3 weeks apart provide definitive confirmation.
Complete blood count, focusing on leukopenia and thrombocytopenia, common early findings.
Liver function tests (ALT, AST) and bilirubin, often elevated in RMSF.
Serum electrolytes, especially hyponatremia, which may accompany severe disease.

Interpretation requires awareness of timing. PCR sensitivity declines after the first week, while antibody titers may remain low during the initial 5‑7 days. Consequently, a negative early serology does not exclude RMSF; repeat testing is advised if clinical suspicion persists.

Follow‑up testing should repeat serology after 7‑10 days to document a four‑fold rise in IgG titer. Persistent abnormalities in platelet count or hepatic enzymes warrant continued monitoring until they normalize, indicating therapeutic response.

Factors Influencing Risk

Tick Identification

Accurate identification of the tick that has bitten a child is a critical step in determining which laboratory investigations are warranted. Species, developmental stage, and duration of attachment directly influence the risk of pathogen transmission and guide the selection of serologic or molecular tests.

Key identification elements:

Species – Recognize distinguishing markings, color patterns, and body shape to differentiate Ixodes, Dermacentor, Amblyomma, or Rhipicephalus species.
Life stage – Determine whether the tick is a larva, nymph, or adult; nymphs of Ixodes scapularis and I. pacificus are most commonly associated with early‑stage Lyme disease.
Engorgement level – Assess the degree of blood intake; a fully engorged tick suggests a longer attachment period and higher transmission probability.
Geographic origin – Correlate the location of the bite with regional tick distribution maps to narrow possible pathogen vectors.
Photographic documentation – Capture clear images for expert consultation when field identification is uncertain.

Identifying these characteristics informs the clinician’s choice of tests. For example, a nymphal Ixodes bite in an endemic area typically prompts Lyme disease serology (ELISA followed by Western blot) and, if the tick was attached for ≥24 hours, consideration of a PCR assay for Borrelia DNA. A Dermacentor bite in a region where Rickettsia rickettsii is prevalent may lead to ordering an acute‑phase IgM immunofluorescence assay for spotted‑fever rickettsiosis. When the tick species is unknown or identification is inconclusive, a broader panel that includes assays for Anaplasma, Ehrlichia, and Babesia should be contemplated.

Prompt, precise tick identification therefore streamlines diagnostic pathways, reduces unnecessary testing, and facilitates early, targeted treatment for children exposed to tick‑borne pathogens.

Duration of Attachment

The length of time a tick remains attached directly influences the likelihood of pathogen transmission and determines which laboratory examinations are warranted for a child after the bite.

If the tick was attached for less than 24 hours, the probability of infection with tick‑borne bacteria such as Borrelia burgdorferi is low; routine monitoring without immediate testing is generally sufficient.

When attachment lasted between 24 and 48 hours, the risk of early Lyme disease and other infections rises. In this interval, the following investigations are recommended:

Enzyme‑linked immunosorbent assay (ELISA) for Lyme disease antibodies, followed by a confirmatory Western blot if positive.
Polymerase chain reaction (PCR) testing for Anaplasma phagocytophilum and Babesia microti if clinical signs suggest these infections.
Complete blood count with differential to detect leukopenia or thrombocytopenia.

If the tick remained attached for more than 48 hours, the risk of transmission reaches its peak. Comprehensive testing should include:

Two‑tiered Lyme serology (ELISA + Western blot).
PCR panels for Ehrlichia chaffeensis, Anaplasma, and Babesia.
Liver function tests (ALT, AST) to identify hepatic involvement.
Renal panel (creatinine, BUN) to assess kidney function before initiating antimicrobial therapy.

Duration thresholds guide clinicians in selecting appropriate diagnostics and, when necessary, initiating empiric antibiotic treatment promptly.

Geographic Location

Geographic location determines which tick‑borne pathogens are likely to have been transmitted, guiding the selection of laboratory investigations for a child who has been bitten.

In the Northeastern United States, the Upper Midwest and parts of Canada, order serology for Borrelia burgdorferi (ELISA followed by Western blot) and polymerase chain reaction (PCR) for Borrelia DNA if early disease is suspected. Consider a complete blood count (CBC) and liver function tests (LFTs) to detect hemolytic anemia associated with Babesia microti, which co‑occurs in the same regions.
In the Pacific Northwest, test for Borrelia miyamotoi using PCR or serology, and include CBC with differential to identify thrombocytopenia typical of Anaplasma phagocytophilum infection.
In the Southern United States, especially Texas, Oklahoma and the Gulf Coast, request serologic testing for Rickettsia rickettsii (immunofluorescence assay) and PCR for Ehrlichia chaffeensis. Add a CBC to monitor leukopenia and platelet counts.
In the Midwest and Central Plains, include serology for Powassan virus and PCR for Heartland virus when neurological symptoms appear. Perform serum electrolytes and renal function panels to assess systemic involvement.
In Europe, prioritize testing for Borrelia afzelii and Borrelia garinii (ELISA/Western blot) and for tick‑borne encephalitis virus (IgM/IgG ELISA). Add LFTs and coagulation profiles if severe disease is suspected.

Additional universal tests:

CBC with differential to detect anemia, leukopenia, or thrombocytopenia.
C‑reactive protein (CRP) or erythrocyte sedimentation rate (ESR) for inflammatory response.
Urinalysis for hematuria or proteinuria indicating renal involvement.

Selection of tests must align with the endemic tick species and pathogen distribution in the child’s specific locality.

When to Seek Medical Attention

Red Flag Symptoms

Rash Characteristics

Rash appearance after a tick attachment provides the primary clue for selecting appropriate diagnostics.

The classic lesion of early Lyme disease is erythema migrans. It begins as a small erythematous macule that expands over days to weeks, often exceeding 5 cm in diameter. Typical features include a uniform red border, central clearing that may produce a “bull’s‑eye” pattern, and a smooth, non‑tender surface. Rapid enlargement, asymmetry, or multiple lesions suggest disseminated infection and warrant serologic testing for Borrelia antibodies and, when available, PCR of skin or blood samples.

A maculopapular rash that appears within 48 hours of the bite, especially if accompanied by fever or malaise, may indicate a viral or bacterial co‑infection. Such lesions are usually raised, may coalesce, and can be tender. CBC with differential and culture of the bite site help identify secondary bacterial pathogens; a rapid antigen test for tick‑borne encephalitis virus may be indicated in endemic regions.

Petechial or purpuric eruptions, often localized to the extremities, raise suspicion for Rocky Mountain spotted fever or other rickettsial diseases. These spots are non‑blanching, 1–5 mm in size, and may merge into larger patches. Immediate testing includes PCR for Rickettsia spp. and empiric doxycycline therapy pending results.

Vesicular or bullous lesions, characterized by fluid‑filled blisters that may rupture, can signal tularemia or severe bacterial superinfection. Diagnosis relies on culture of aspirated fluid, serology for Francisella tularensis, and imaging if systemic involvement is suspected.

Key rash descriptors for guiding investigations:

Size > 5 cm, expanding, central clearing → Lyme serology, PCR
Raised, coalescent, early onset (<48 h) → CBC, bacterial culture, viral antigen test
Non‑blanching petechiae/purpura → Rickettsial PCR, doxycycline
Vesicles/bullae → Fluid culture, tularemia serology

Accurate documentation of rash morphology, distribution, and progression enables clinicians to select targeted laboratory assessments promptly, reducing the risk of delayed treatment.

Fever and Flu-Like Symptoms

Fever and flu‑like symptoms in a child who has recently been attached to a tick signal possible early infection and require prompt laboratory assessment.

First‑line investigations include:

Complete blood count with differential to detect leukocytosis, lymphopenia, or thrombocytopenia.
Serum C‑reactive protein and erythrocyte sedimentation rate to gauge inflammatory activity.
Liver function panel (ALT, AST, bilirubin) because several tick‑borne pathogens cause hepatic involvement.
Renal profile (creatinine, urea) to identify early kidney dysfunction.

If the child presents with a rash, joint pain, or persistent fever, add the following targeted tests:

Polymerase chain reaction (PCR) for Borrelia burgdorferi DNA from blood or skin lesion.
Serologic testing for Lyme disease (IgM and IgG ELISA, confirmed by Western blot).
PCR for Anaplasma phagocytophilum and Ehrlichia species when leukopenia or thrombocytopenia is evident.
Serology for Rickettsia spp. if an eschar or petechial rash is observed.

When neurological signs accompany the flu‑like picture, perform:

Lumbar puncture with cerebrospinal fluid analysis, including PCR for Borrelia and viral pathogens.
Magnetic resonance imaging of the brain if focal deficits are present.

Repeat CBC and inflammatory markers after 48–72 hours if initial results are normal but clinical suspicion persists. Early detection through these examinations guides timely antimicrobial therapy and prevents progression to severe disease.

Joint Pain and Swelling

Joint pain and swelling in a child after a tick exposure may signal early Lyme arthritis or other tick‑borne infections. Prompt laboratory evaluation distinguishes inflammatory, infectious, and mechanical causes and guides treatment.

Initial assessment should include a complete blood count to detect leukocytosis or anemia, and inflammatory markers such as erythrocyte sedimentation rate and C‑reactive protein to gauge systemic inflammation. Serologic testing for Borrelia burgdorferi is essential; an enzyme‑linked immunosorbent assay followed by a confirmatory Western blot provides reliable evidence of infection. If serology is negative but clinical suspicion remains high, polymerase chain reaction testing of blood or synovial fluid can identify Borrelia DNA.

When joint effusion is present, arthrocentesis supplies synovial fluid for analysis. Evaluation of fluid cell count, Gram stain, culture, and polymerase chain reaction for Borrelia and other pathogens helps exclude septic arthritis and confirms Lyme arthritis. Additional imaging, such as ultrasound or magnetic resonance imaging, may be ordered to assess joint structure and detect effusions not apparent on physical exam.

Recommended tests for children with joint pain and swelling after a tick bite:

Complete blood count (CBC)
Erythrocyte sedimentation rate (ESR) and C‑reactive protein (CRP)
Borrelia serology: ELISA with reflex Western blot
Polymerase chain reaction (PCR) for Borrelia in blood or synovial fluid (if serology inconclusive)
Synovial fluid analysis: cell count, Gram stain, culture, PCR
Joint imaging (ultrasound or MRI) when indicated

These investigations identify Lyme arthritis promptly, rule out alternative infections, and provide a foundation for targeted antimicrobial or anti‑inflammatory therapy.

Neurological Changes

A tick attachment can transmit pathogens that affect the central and peripheral nervous systems. Early recognition of neurological involvement is essential because delayed treatment may lead to persistent deficits.

Observe the child for facial weakness, meningitic signs (headache, photophobia, neck stiffness), limb paresthesia, ataxia, seizures, or altered mental status. Any of these manifestations warrants immediate evaluation.

Recommended investigations for suspected neurotoxicity include:

Detailed neurological examination documenting cranial nerve function, motor strength, reflexes, coordination, and sensory perception.
Cerebrospinal fluid analysis obtained via lumbar puncture; assess cell count, protein, glucose, and perform polymerase chain reaction for Borrelia burgdorferi and other tick‑borne agents.
Magnetic resonance imaging of the brain and spinal cord with contrast to identify meningitis, encephalitis, or demyelinating lesions.
Electroencephalography when seizures or abnormal cortical activity are suspected.
Serologic testing for specific antibodies (IgM/IgG) against Lyme disease, tick‑borne encephalitis virus, and other relevant organisms.

These studies, performed promptly after symptom onset, provide the data necessary to confirm neuroinfection, gauge disease severity, and guide antimicrobial or supportive therapy.

Consulting a Healthcare Professional

Importance of Timely Evaluation

Timely evaluation after a tick exposure is essential to prevent severe complications in children. Early detection of infection allows prompt treatment, reduces the risk of disease progression, and limits long‑term sequelae.

The initial clinical assessment should include:

Physical examination of the bite site for attachment duration, erythema, or the presence of a bull’s‑eye lesion.
Review of symptoms such as fever, headache, fatigue, or joint pain.
Documentation of the tick’s geographic origin and estimated time of attachment.

Laboratory investigations recommended when evaluation occurs promptly:

Complete blood count to identify leukocytosis or thrombocytopenia.
C‑reactive protein or erythrocyte sedimentation rate for inflammatory activity.
Serologic testing for Borrelia burgdorferi antibodies (ELISA followed by Western blot if positive) when the bite occurred in a Lyme‑endemic area or when erythema migrans is observed.
PCR assay for tick‑borne pathogens (e.g., Anaplasma, Ehrlichia) in cases of systemic symptoms.
Urinalysis to detect early renal involvement in severe infections.

If the child presents within 24–48 hours of the bite, prophylactic antibiotic therapy may be considered, and laboratory testing can be limited to baseline blood work. Delayed presentation warrants a comprehensive panel, including repeat serology after two weeks to capture seroconversion.

Prompt medical attention also facilitates education of caregivers about tick removal techniques, signs of infection, and the schedule for follow‑up visits, thereby reinforcing preventive measures and ensuring ongoing monitoring.

Information to Provide to the Doctor

When you see the physician, give a complete, factual account of the exposure and the child’s health status.

State the exact date and approximate time when the bite occurred. Describe the body region where the tick was attached and whether it was on the scalp, torso, limbs, or another area. Note how long the tick remained attached before removal; if the duration is unknown, estimate the number of days it may have been present.

Provide details about the tick itself: whether it was engorged, its size (e.g., 2 mm, 5 mm), and any visible markings that could help identify the species. If you photographed or saved the tick, mention that the image or specimen is available for examination.

Explain how the tick was removed: describe the tool used (fine‑point tweezers, tick‑removal device) and the technique (grasping close to the skin, steady upward motion). Indicate whether the mouthparts were left in the skin.

List any symptoms the child has experienced since the bite: fever, headache, fatigue, rash (including description of shape, color, and location), joint pain, or neurological signs such as facial weakness. Note the onset date of each symptom.

Report the child’s recent medical background: current medications, known drug allergies, chronic conditions, and immunization record, especially the status of any tick‑borne disease vaccines if applicable. Include any recent travel to regions where tick‑borne infections are endemic.

Mention any prophylactic measures already taken: administration of antibiotics (drug, dose, and timing), use of topical repellents, or other preventive actions.

Summarize the information in a concise list for the clinician’s reference:

Date and time of bite
Body site of attachment
Estimated attachment duration
Tick description (size, engorgement, species clues)
Removal method and tool used
Presence and timing of symptoms (fever, rash, joint pain, neurological signs)
Current medications, allergies, chronic illnesses, vaccination status
Recent travel to high‑risk areas
Prophylactic treatments already given

Providing these data enables the physician to select appropriate laboratory assessments and determine the need for immediate or delayed therapy.

Diagnostic Testing Considerations

Initial Assessment by a Doctor

Physical Examination

A thorough physical examination is the first step in evaluating a child after a tick attachment. The clinician should:

Inspect the bite site for an engorged tick, erythema, or a target‑shaped lesion (erythema migrans). Remove any remaining tick parts with fine‑point tweezers, avoiding compression of the mouthparts.
Survey the entire skin surface for additional erythematous lesions, vesicles, or petechiae that may indicate secondary infection or disseminated disease.
Measure temperature and assess for fever, chills, or malaise, which can accompany early systemic involvement.
Palpate regional lymph nodes for enlargement or tenderness, especially in the axillary, cervical, and inguinal chains corresponding to the bite location.
Conduct a focused neurological assessment, checking cranial nerve function, muscle strength, reflexes, and coordination to detect early signs of neuroborreliosis or other tick‑borne neurologic disorders.
Examine joints for swelling, warmth, or limited range of motion, as arthritic manifestations may emerge within weeks of exposure.
Record vital signs, including heart rate and blood pressure, to identify any hemodynamic changes that could suggest severe infection.

Documentation of these findings establishes a baseline for monitoring disease progression and guides the selection of laboratory and imaging studies, if indicated.

Symptom Review

A thorough symptom review is the first step in evaluating a child who has been exposed to a tick. Clinicians must systematically inquire about any changes that could signal infection or disease progression.

Fever or chills, especially if persistent or rising above 38 °C (100.4 °F)
Skin lesions: erythema at the bite site, expanding rash, or a target‑shaped lesion (suggestive of early Lyme disease)
Joint discomfort or swelling, particularly in the knees, ankles, or wrists
Neurological signs: headache, neck stiffness, facial weakness, tingling, or numbness
Gastrointestinal symptoms: nausea, vomiting, abdominal pain, or diarrhea
General malaise, fatigue, or unexplained weight loss
Recent onset of flu‑like illness not attributable to another cause

The review should cover the timing of each symptom relative to the bite, noting whether signs appeared within 24 hours, several days, or weeks later. Documenting the precise chronology aids in distinguishing early localized reactions from disseminated infections and guides subsequent laboratory or imaging investigations.

Specific Tests and Their Timing

Lyme Disease Testing

Lyme disease is the most common tick‑borne infection in children, and early detection guides timely treatment. Testing should be ordered when a bite is recent, the tick was attached for more than 24 hours, or the child shows symptoms such as fever, rash, or joint pain.

Enzyme‑linked immunosorbent assay (ELISA) – first‑line serologic screen for IgM and IgG antibodies; performed 3–4 weeks after exposure for optimal sensitivity.
Western blot – confirmatory test required when ELISA is positive; distinguishes early‑stage IgM from later‑stage IgG responses.
Polymerase chain reaction (PCR) – detects Borrelia DNA in synovial fluid, cerebrospinal fluid, or skin biopsies; reserved for disseminated disease or atypical presentations.
Complete blood count (CBC) with differential – evaluates for leukocytosis or anemia that may accompany infection.
Erythrocyte sedimentation rate (ESR) and C‑reactive protein (CRP) – assess inflammatory activity, useful in monitoring disease progression.

Testing timing matters: serologic assays are unreliable within the first week of a bite because antibodies may not yet be detectable. In cases of an erythema migrans rash, clinicians may initiate therapy without laboratory confirmation, but a baseline ELISA can be helpful for future monitoring.

Guidelines from the Centers for Disease Control and Prevention and the American Academy of Pediatrics recommend the two‑step serology (ELISA followed by Western blot) as the standard diagnostic algorithm for children with suspected Lyme disease after a tick encounter.

ELISA/IFA Screening

When a child is bitten by a tick, laboratory evaluation commonly begins with serologic screening using ELISA and, when indicated, confirmation by indirect immunofluorescence assay (IFA).

ELISA detects IgM and IgG antibodies directed against Borrelia burgdorferi and other tick‑borne pathogens. The assay provides high sensitivity after the second week of exposure; earlier testing may yield false‑negative results because antibodies have not yet reached detectable levels. Positive ELISA results require confirmation because cross‑reactivity can produce false‑positives.

IFA serves as the confirmatory test. It visualizes antibody binding to antigen‑coated slides under fluorescence microscopy, offering greater specificity. IFA is typically performed after a positive ELISA, especially when clinical suspicion remains high despite a borderline ELISA outcome. The assay detects both IgM and IgG, allowing assessment of recent versus past infection.

Practical considerations for pediatric patients:

Obtain a blood sample at least 14 days after the tick bite or onset of symptoms.
Perform ELISA first; if the result is positive or equivocal, proceed to IFA.
Interpret IgM positivity as indicative of recent infection; IgG positivity suggests established or past exposure.
If both ELISA and IFA are negative but the child shows persistent erythema migrans, fever, or neurologic signs, repeat testing in 2–3 weeks.
Document the specific pathogen tested (e.g., B. burgdorferi, Anaplasma, Ehrlichia) because serologic panels differ.

These steps ensure that serologic screening and confirmation are applied efficiently, guiding timely treatment decisions for children after tick exposure.

Western Blot Confirmation

After a tick bite, serologic evaluation for Lyme disease typically begins with an enzyme‑linked immunosorbent assay (ELISA). A positive ELISA result must be confirmed by Western blot to verify the presence of antibodies specific to Borrelia burgdorferi.

Western blot separates bacterial proteins by electrophoresis and detects patient antibodies that bind to distinct antigenic bands. The test distinguishes true infection from cross‑reactive antibodies that can cause false‑positive ELISA results.

The assay is most reliable when performed at least three weeks after the bite or after the onset of characteristic symptoms. Testing sooner may miss early seroconversion and yield a negative result despite infection.

Interpretation follows established criteria:

IgM positivity requires at least two of the three bands (23 kDa, 39 kDa, 41 kDa).
IgG positivity requires at least five of the ten bands (including 18 kDa, 28 kDa, 30 kDa, 41 kDa, 45 kDa, 58 kDa, 66 kDa, 93 kDa, 100 kDa, 120 kDa).
Presence of the requisite bands confirms exposure to the pathogen; absence suggests either no infection or testing performed before antibody development.

Specimens are serum or plasma obtained by venipuncture. Laboratories must adhere to quality‑controlled protocols and report both IgM and IgG band patterns. Limitations include reduced sensitivity during the earliest phase of disease and potential persistence of IgG antibodies after successful treatment, which may not indicate active infection.

Key points:

Western blot serves as confirmatory test after a positive ELISA.
Optimal timing: ≥3 weeks post‑exposure or symptom onset.
Positive result defined by specific band patterns for IgM and IgG.
Results guide clinical decisions regarding antibiotic therapy.

Other Tick-Borne Disease Panels

When a child presents after a tick attachment, clinicians often begin with testing for Lyme disease, but additional tick‑borne infections may require separate panels. These panels group assays for pathogens that share the same vector and can produce overlapping clinical pictures.

A comprehensive “Other Tick‑Borne Disease Panel” typically includes:

Babesia microti – PCR from whole blood for acute infection; indirect fluorescent antibody (IFA) titers for convalescent assessment.
Anaplasma phagocytophilum – Real‑time PCR on whole blood; IgG IFA for later-stage confirmation.
Ehrlichia chaffeensis and Ehrlichia ewingii – PCR on whole blood; serology (IgM/IgG) performed 2–4 weeks after symptom onset.
Rickettsia rickettsii (Rocky Mountain spotted fever) – PCR from skin biopsy or blood; immunofluorescence assay for IgG rising titers.
Bartonella henselae – PCR on blood or tissue; enzyme‑linked immunosorbent assay (ELISA) for IgG and IgM antibodies.
Tick‑borne relapsing fever Borrelia species – PCR on blood during febrile spikes; serology is less reliable, but can be used for epidemiologic confirmation.

Specimen selection follows pathogen biology: intracellular bacteria (Anaplasma, Ehrlichia) require whole‑blood samples collected in EDTA; Babesia detection prefers fresh whole blood for PCR; Rickettsial agents are best identified from skin lesions when available. Timing is critical: PCR yields the highest sensitivity within the first week of illness, while serologic conversion generally appears after 7–14 days.

Ordering these panels should be guided by exposure history, geographic prevalence, and clinical signs such as fever, rash, thrombocytopenia, or hemolytic anemia. Positive results prompt pathogen‑specific therapy—e.g., doxycycline for Anaplasma, Ehrlichia, and Rickettsia; atovaquone‑azithromycin for Babesia; and supportive care for relapsing fever.

In practice, a single multiplex assay that screens for the above organisms can reduce turnaround time and conserve specimen volume, but laboratories vary in availability. When multiplex testing is unavailable, clinicians must request individual PCR or serology assays based on the most likely agents.

Complete Blood Count (CBC)

A Complete Blood Count (CBC) is a standard laboratory panel ordered when a child has been exposed to a tick. The test provides a rapid overview of hematologic status, identifying abnormalities that may signal early infection or immune response.

Key parameters evaluated in a CBC include:

White blood cell (WBC) count and differential, which can reveal leukocytosis, leukopenia, or shifts toward neutrophils or lymphocytes,
Hemoglobin concentration and hematocrit, indicating possible anemia,
Platelet count, useful for detecting thrombocytopenia that may accompany certain tick‑borne illnesses.

Interpretation of results should consider the epidemiology of local tick‑borne pathogens and the time elapsed since the bite. Elevated WBC with a neutrophilic predominance may suggest bacterial infection, whereas lymphocytosis can be associated with viral or rickettsial diseases. A decreasing platelet count warrants close monitoring, as it can precede severe complications such as hemorrhagic fever. Repeat CBCs are typically performed 1–2 weeks after the initial assessment to track trends and guide further diagnostic steps.

Liver and Kidney Function Tests (if indicated)

Liver and kidney function tests are considered when a child exhibits signs that suggest systemic involvement after a tick bite. Elevated transaminases, bilirubin, or abnormal renal markers may indicate infection‑related organ stress or early complications such as Lyme disease–associated hepatitis or acute kidney injury.

Indications for ordering these tests include:

Persistent fever beyond 48 hours without an alternative explanation.
Generalized rash, especially if atypical or expanding.
Laboratory evidence of hemolysis or thrombocytopenia.
Neurological symptoms that could reflect disseminated infection.
History of prolonged tick attachment (> 24 hours) in a region with high prevalence of tick‑borne pathogens.

Typical panels consist of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, total and direct bilirubin for hepatic assessment, and blood urea nitrogen (BUN), creatinine, and electrolytes for renal evaluation. Results guide further management: normal values may allow continuation of observation, while abnormalities prompt antimicrobial therapy escalation, referral to a specialist, or additional imaging.

Timely interpretation of liver and kidney function tests helps prevent progression to severe disease and supports evidence‑based decision‑making in pediatric tick‑bite care.

Interpreting Test Results

False Positives and Negatives

Testing after a tick bite in a child must be evaluated for accuracy. False‑positive results occur when a test indicates infection despite the absence of disease; false‑negative results miss an existing infection. Both outcomes can misguide clinical decisions, leading to unnecessary treatment or delayed therapy.

Common assays include:

Enzyme‑linked immunosorbent assay (ELISA) for antibodies to Borrelia burgdorferi.
Western blot confirmation of ELISA‑positive samples.
Polymerase chain reaction (PCR) on skin, blood, or cerebrospinal fluid.
Complete blood count and inflammatory markers (C‑reactive protein, erythrocyte sedimentation rate).
Liver function tests when systemic involvement is suspected.

Factors influencing false‑positive findings:

Cross‑reactivity with antibodies to other spirochetes or viral infections.
Recent vaccination or exposure to unrelated pathogens.
Laboratory contamination or technical error.

Factors influencing false‑negative findings:

Testing performed before seroconversion (typically within two weeks of bite).
Low bacterial load in early infection reducing PCR detectability.
Immunosuppression diminishing antibody production.
Inadequate sample collection or handling.

Interpretation guidelines:

A positive ELISA must be confirmed by Western blot; isolated ELISA positivity without confirmation is insufficient for diagnosis.
Negative serology in the first weeks does not exclude early Lyme disease; repeat testing after three weeks is advisable if symptoms persist.
PCR positivity, even with negative serology, confirms infection because it detects pathogen DNA directly.
Consistent clinical signs (erythema migrans, fever, joint pain) combined with laboratory data strengthen diagnostic confidence and reduce reliance on single test outcomes.

Awareness of test limitations prevents over‑treatment and ensures timely initiation of antibiotics when true infection is identified.

The Role of Clinical Judgement

Clinical judgement determines which investigations are warranted after a pediatric tick exposure. The decision hinges on the bite’s duration, the child’s symptom profile, and the epidemiology of tick‑borne pathogens in the area.

When the tick has been attached for less than 24 hours and the child shows no fever, rash, or joint pain, observation and a thorough physical exam may suffice. If the tick was attached longer than 36 hours, or if the child presents with erythema migrans, fever, headache, or arthralgia, further testing becomes necessary.

Typical investigations ordered based on clinical assessment include:

Complete blood count to detect early hematologic changes.
Serologic testing for Borrelia burgdorferi (ELISA followed by Western blot) when Lyme disease is suspected.
Polymerase chain reaction for Anaplasma or Ehrlichia in regions where these agents are prevalent.
Liver function panel if systemic symptoms suggest babesiosis or other co‑infections.
Urinalysis when urinary symptoms accompany the bite.

The clinician may also decide to repeat serology after two weeks if initial results are negative but clinical suspicion remains high. Prompt initiation of empiric antibiotics is considered when the assessment indicates a high probability of infection, even before laboratory confirmation.

Management and Follow-Up

Treatment Approaches

Antibiotic Therapy for Bacterial Infections

After a tick bite, clinicians evaluate the child for bacterial pathogens that may require immediate antimicrobial intervention. Laboratory studies such as serology for Borrelia, polymerase chain reaction for Anaplasma, and complete blood count help identify infection, but treatment may start before results when clinical signs are evident.

Empiric therapy is indicated when erythema migrans appears, when the bite occurred in an endemic area during peak season, or when systemic symptoms develop within 72 hours. In such cases, prompt antibiotic administration reduces the risk of complications.

Doxycycline – 4 mg/kg per dose, twice daily, for 10–21 days; preferred for children ≥8 years and for coverage of Borrelia, Anaplasma, and Ehrlichia.
Amoxicillin – 50 mg/kg per dose, three times daily, for 14–21 days; used in children <8 years when doxycycline is contraindicated.
Cefuroxime axetil – 30 mg/kg per dose, twice daily, for 14–21 days; alternative for amoxicillin intolerance or when broader coverage is required.

Therapy duration aligns with the identified organism: Lyme disease generally requires 14–21 days, whereas anaplasmosis often resolves with a 7–10‑day course. Follow‑up testing after completion confirms seroconversion or clearance; persistent symptoms prompt reassessment of regimen and possible extension of treatment.

Laboratory confirmation guides the choice of agent, but the presence of characteristic rash or systemic signs justifies immediate initiation of the recommended antibiotic to prevent disease progression.

Symptomatic Relief

A tick bite can cause local irritation, pain, and itching that interfere with a child’s comfort. Prompt cleaning of the site with soap and water reduces bacterial contamination and removes residual saliva that may trigger inflammation. Applying a cold compress for 10–15 minutes eases swelling and dulls pain without pharmacologic intervention.

Analgesic and anti‑itch medications complement hygiene measures. Oral acetaminophen or ibuprofen, dosed according to weight, provide reliable pain relief and reduce fever if it develops. Non‑sedating antihistamines such as cetirizine or loratadine counteract histamine‑mediated itching; a single dose is often sufficient, with a second dose if symptoms persist. For pronounced local reactions, a short course of low‑potency topical corticosteroid (hydrocortisone 1 %) applied twice daily for up to three days diminishes erythema and pruritus.

Supportive care sustains overall wellbeing while diagnostic procedures are arranged. Encourage regular fluid intake and balanced meals to prevent dehydration and maintain energy levels. Ensure the child rests in a calm environment; excessive activity can exacerbate discomfort and obscure early signs of infection.

Monitoring remains essential. Record temperature, note any expanding rash, joint pain, or neurological changes, and report these promptly. Early recognition of systemic involvement guides clinicians in selecting appropriate laboratory examinations and antimicrobial therapy.

Long-Term Monitoring

Tracking Symptoms

After a tick bite, close observation of the child’s condition guides the selection of diagnostic procedures. Early detection of disease hinges on recognizing specific clinical changes; therefore, systematic symptom tracking is essential.

Record the following signs at least daily for the first two weeks, extending observation if any abnormality appears:

Fever or chills, especially a temperature above 38 °C (100.4 °F).
Headache, neck stiffness, or photophobia.
Muscle or joint pain that is new or worsening.
Rash development: a circular erythema at the bite site, expanding lesions, or any non‑specific skin changes.
Fatigue, malaise, or loss of appetite.
Neurological manifestations such as tingling, weakness, or difficulty concentrating.
Gastrointestinal symptoms, including nausea, vomiting, or abdominal pain.

If any of these symptoms emerge, the following investigations are typically ordered:

Complete blood count with differential to identify leukocytosis or anemia.
Serum inflammatory markers (C‑reactive protein, erythrocyte sedimentation rate).
Liver function tests, because hepatic involvement may accompany certain tick‑borne infections.
Serologic assays for Borrelia burgdorferi (ELISA followed by Western blot) when erythema migrans or systemic signs are present.
Polymerase chain reaction testing for Anaplasma, Ehrlichia, or Babesia if fever persists without clear source.
Urinalysis to detect hematuria or proteinuria indicating renal involvement.
Neuroimaging (MRI) or lumbar puncture if neurological symptoms develop.

Documenting the onset, duration, and progression of each symptom enables clinicians to differentiate between benign local reactions and early systemic infection, ensuring timely, targeted testing and treatment. Continuous monitoring should continue for at least six weeks, as some tick‑borne illnesses manifest later in the course.

Follow-Up Appointments

After a tick bite, the initial evaluation includes laboratory testing for Lyme disease, anaplasmosis, and other tick‑borne infections. Follow‑up appointments are essential to confirm treatment success, detect delayed seroconversion, and identify emerging symptoms.

The first follow‑up should occur 2–3 weeks after the initial visit. During this visit, the clinician reviews the child’s symptom diary, repeats serologic testing if the initial result was negative, and assesses for rash expansion or new neurologic signs. A second appointment is recommended 6–8 weeks post‑exposure to verify that antibody titers have risen appropriately and to ensure that any prescribed antibiotics have been completed without adverse effects.

Key components of each follow‑up visit:

Review of fever, headache, fatigue, joint pain, and neurological findings.
Physical examination focusing on the erythema migrans site and lymphadenopathy.
Repeat serology (ELISA and Western blot) when the first test was negative or equivocal.
Evaluation of medication tolerance and adherence.
Discussion of preventive measures for future exposures.

If symptoms persist beyond 8 weeks, a third visit may be scheduled to consider alternative diagnoses, extended antimicrobial therapy, or referral to a pediatric infectious‑disease specialist. Prompt documentation of test results and symptom progression during each appointment supports timely decision‑making and reduces the risk of chronic complications.