Tick Bite ICD-10 Codes and How Everest Can Help Practices
When patients present with a tick bite, accurate documentation and proper coding are essential—not only for patient care but also for securing timely reimbursements. Tick bites can result in anything from mild irritation to serious infectious diseases, and medical providers must correctly assign ICD-10 codes to reflect both the encounter and any associated conditions.
This article outlines everything you need to know about tick bite ICD-10 coding, related infectious disease codes, clinical scenarios, and how Everest can streamline the entire billing process for your practice.
Understanding the ICD-10 Codes for Tick Bites
Tick Bite (No Disease Diagnosis Yet)
Use W57.XXXA when the patient presents for care due to a tick bite, but there’s no confirmed infection yet.
W57.XXXA – Bitten or stung by nonvenomous insect and other nonvenomous arthropods, initial encounter
W57.XXXD – Subsequent encounter
W57.XXXS – Sequela (for long-term effects from a prior tick bite)
This code should be used as a secondary code. It identifies the external cause but must be paired with a code that explains why the encounter occurred (e.g., observation, fever, pain, etc.).
ICD-10 Codes for Tick-Borne Diseases
If a tick bite leads to a diagnosed condition, use the disease-specific code as the primary diagnosis, and add W57.XXXA as an external cause.
Lyme Disease - A69.20 Lyme disease, unspecified
A69.21 Meningitis due to Lyme disease
A69.22 Other neurologic disorders in Lyme disease
Rocky Mountain Spotted Fever A77.0 Spotted fever due to Rickettsia rickettsii
Ehrlichiosis A79.89 Other rickettsioses
Anaplasmosis A79.82 Human granulocytic anaplasmosis
Babesiosis B60.0 Babesiosis
Tick-Borne Relapsing Fever A68.0 Relapsing fever due to Borrelia recurrentis
Tularemia A21.9 Tularemia, unspecified
Colorado Tick Fever A93.1 Colorado tick fever
Tick Paralysis G73.1 Other myasthenic syndromes
Other Useful ICD-10 Codes
Z20.828 Contact with and suspected exposure to other viral diseases
Z11.59 Encounter for screening for other viral diseases
Z03.818 Encounter for observation for suspected exposure
R50.9 Fever, unspecified (often a symptom of early tick-borne disease)
R51.9 Headache, unspecified
Clinical Scenarios and Billing Combinations
Scenario 1: Prophylactic Treatment After a Tick Bite
Primary Code: Z20.828 – Suspected exposure
Secondary Code: W57.XXXA – Tick bite
Modifier: If prophylactic antibiotics (e.g., doxycycline) are given, bill the office visit with appropriate E/M code and medication administration code
Scenario 2: Patient Diagnosed with Lyme Disease with Neuro Symptoms
Primary Code: A69.22 – Neurologic disorder in Lyme disease
Secondary Code: W57.XXXA – External cause
Add: Office visit code, labs (e.g., CPT 87477 for Lyme)
Scenario 3: Suspected Ehrlichiosis with Fever
Primary Code: A79.89 – Other rickettsioses
Secondary Code: W57.XXXA – Tick bite
Symptom Codes: R50.9 (fever), R51.9 (headache)
Challenges in Billing Tick-Bite Cases
Medical practices frequently encounter claim denials or underpayments when handling tick-bite cases. This can be due to:
Misuse of W57 codes as primary diagnoses
Missing documentation of confirmed diagnosis
Inconsistent use of external cause and symptom codes
Failure to document timeline of encounters (initial, subsequent, sequela)
Additionally, the need to coordinate with labs, track follow-up visits, and manage payer-specific rules makes tick-borne cases uniquely complex in the billing world.
How Everest Can Help Your Practice
Everest has extensive experience helping primary care providers, urgent care centers, and infectious disease specialists bill accurately for environmental exposures like tick bites.
Expert ICD-10 and CPT Coding
We ensure the correct hierarchical coding structure, apply the appropriate modifiers, and ensure coding specificity that meets payer requirements.
Optimized Claim Submissions
We review all claims for completeness, accuracy, and compliance with documentation standards before submission—drastically reducing the chance of denials.
Denial Management and Appeals
Our team actively tracks denials and initiates timely appeals with supporting documentation, ensuring maximum reimbursement.
AR Recovery and Revenue Cycle Support
Tick-bite claims can often linger in accounts receivable due to coding issues or payer rejections. We offer AR recovery services to clean up unresolved claims.
Provider Education & EHR Integration
We work directly with your clinical and coding staff to implement tick-bite documentation templates in your EHR system, improving coding compliance and speed.
Final Thoughts
While tick bites may be a common summertime health issue, their medical billing is far from simple. Proper ICD-10 coding and billing for both the tick bite and any subsequent illness are critical for ensuring timely and full reimbursement.
Everest provides expert support so your practice can:
Avoid documentation pitfalls
Submit clean claims the first time
Recover more revenue
Spend less time chasing unpaid bills
