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ICD-10 Guide
ICD-10 CodesA83.9

A83.9

Tick-borne viral encephalitis, unspecified

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/05/2025

Code Description

ICD-10 A83.9 is a billable code used to indicate a diagnosis of tick-borne viral encephalitis, unspecified.

Key Diagnostic Point:

Tick-borne viral encephalitis (TBE) is a viral infection that affects the central nervous system (CNS) and is transmitted primarily through the bite of infected ticks. The disease is caused by the tick-borne encephalitis virus (TBEV), which can lead to severe neurological complications, including encephalitis, meningitis, and myelitis. Symptoms typically include fever, headache, fatigue, and neurological deficits, which may progress to seizures, confusion, and coma in severe cases. The clinical presentation can vary widely, with some patients experiencing mild flu-like symptoms while others develop serious CNS involvement. Diagnosis is primarily based on clinical presentation, serological testing for TBEV antibodies, and sometimes PCR testing of cerebrospinal fluid (CSF). Vaccination against TBE is available and recommended for individuals at high risk, such as those living in or traveling to endemic areas. The unspecified designation indicates that the specific type or severity of the encephalitis is not documented, which may complicate treatment and management decisions.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variability in clinical presentation and severity of the disease.
  • Need for serological and possibly PCR testing for accurate diagnosis.
  • Documentation of vaccination status can impact coding.
  • Differentiation from other viral CNS infections.

Audit Risk Factors

  • Inadequate documentation of clinical symptoms.
  • Failure to document vaccination status.
  • Misclassification of the severity of the condition.
  • Lack of supporting laboratory results.

Specialty Focus

Medical Specialties

Infectious Disease

Documentation Requirements

Detailed clinical notes on symptoms, laboratory results, and vaccination history.

Common Clinical Scenarios

Patients presenting with neurological symptoms after tick exposure.

Billing Considerations

Ensure thorough documentation of travel history and tick exposure.

Neurology

Documentation Requirements

Neurological examination findings, imaging results, and treatment plans.

Common Clinical Scenarios

Patients with acute neurological deficits and suspected viral encephalitis.

Billing Considerations

Document any differential diagnoses considered and ruled out.

Coding Guidelines

Inclusion Criteria

Use A83.9 When
  • Follow the official ICD
  • CM coding guidelines, ensuring that the code is used only when the diagnosis of tick
  • borne viral encephalitis is confirmed or strongly suspected
  • Document any relevant laboratory findings and clinical symptoms that support the diagnosis

Exclusion Criteria

Do NOT use A83.9 When
No specific exclusions found.

Related CPT Codes

87491CPT Code

Viral testing for tick-borne encephalitis

Clinical Scenario

Used when serological testing is performed to confirm TBE.

Documentation Requirements

Document the reason for testing and results.

Specialty Considerations

Infectious disease specialists should ensure comprehensive testing.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of tick-borne viral encephalitis, improving the accuracy of data collection and reimbursement processes. A83.9 provides a clear designation for unspecified cases, aiding in epidemiological tracking.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of tick-borne viral encephalitis, improving the accuracy of data collection and reimbursement processes. A83.9 provides a clear designation for unspecified cases, aiding in epidemiological tracking.

Reimbursement & Billing Impact

reimbursement processes. A83.9 provides a clear designation for unspecified cases, aiding in epidemiological tracking.

Resources

Clinical References

  • •
    CDC Tick-Borne Diseases

Coding & Billing References

  • •
    CDC Tick-Borne Diseases

Frequently Asked Questions

What are the common symptoms of tick-borne viral encephalitis?

Common symptoms include fever, headache, fatigue, and neurological signs such as confusion, seizures, and altered consciousness.

How is tick-borne viral encephalitis diagnosed?

Diagnosis is based on clinical symptoms, serological testing for TBEV antibodies, and PCR testing of cerebrospinal fluid.

Is there a vaccine for tick-borne viral encephalitis?

Yes, there is a vaccine available for individuals at high risk, particularly those living in or traveling to endemic areas.