1. ICD-10-CM Codes
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2. A00-B99
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3. A80-A89
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4. A84-
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5. 2023 ICD-10-CM Diagnosis Code A84.9

2023 ICD-10-CM Diagnosis Code A84.9

Tick-borne viral encephalitis, unspecified

2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code

• A84.9 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
• The 2023 edition of ICD-10-CM A84.9 became effective on October 1, 2022.
• This is the American ICD-10-CM version of A84.9 - other international versions of ICD-10 A84.9 may differ.

• Tick-borne viral encephalitis
• Viral encephalitis, tick borne

• Encephalitis caused by neurotropic viruses that are transmitted via the bite of ticks. In europe, the diseases are caused by encephalitis viruses, tick-borne, which give rise to russian spring-summer encephalitis, central european encephalitis, louping ill encephalitis, and related disorders. Powassan encephalitis occurs in north america and russia and is caused by the powassan virus. Aseptic meningitis and rarely encephalitis may complicate colorado tick fever which is endemic to mountainous regions of the western United States. (from Joynt, Clinical Neurology, 1996, ch26, pp14-5)

• 023 Craniotomy with major device implant or acute complex cns principal diagnosis with mcc or chemotherapy implant or epilepsy with neurostimulator
• 024 Craniotomy with major device implant or acute complex cns principal diagnosis without mcc
• 097 Non-bacterial infection of nervous system except viral meningitis with mcc
• 098 Non-bacterial infection of nervous system except viral meningitis with cc
• 099 Non-bacterial infection of nervous system except viral meningitis without cc/mcc

Convert A84.9 to ICD-9-CM

• 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
• 2017 (effective 10/1/2016): No change
• 2018 (effective 10/1/2017): No change
• 2019 (effective 10/1/2018): No change
• 2020 (effective 10/1/2019): No change
• 2021 (effective 10/1/2020): No change
• 2022 (effective 10/1/2021): No change
• 2023 (effective 10/1/2022): No change

• Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) G04.90
  ICD-10-CM Diagnosis Code G04.90

  Encephalitis and encephalomyelitis, unspecified

  2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code

  Applicable To

  • Ventriculitis (cerebral) NOS
  • viral, virus A86
    ICD-10-CM Diagnosis Code A86

    Unspecified viral encephalitis

    2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code

    Applicable To

    • Viral encephalomyelitis NOS
    • Viral meningoencephalitis NOS
    • arthropod-borne NEC A85.2
      ICD-10-CM Diagnosis Code A85.2

      Arthropod-borne viral encephalitis, unspecified

      2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code

      Type 1 Excludes

      • West nile virus with encephalitis (A92.31)
      • tick-borne A84.9
  • tick-borne A84.9
• Infection, infected, infective (opportunistic) B99.9
  ICD-10-CM Diagnosis Code B99.9

  Unspecified infectious disease

  2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
  • virus, viral NOS B34.9
    ICD-10-CM Diagnosis Code B34.9

    Viral infection, unspecified

    2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code

    Applicable To

    • Viremia NOS
    • encephalitis, tick-borne A84.9

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.