2020 ICD-10-CM Diagnosis Code A84.9

Tick-borne viral encephalitis, unspecified

    2016 2017 2018 2019 2020 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 2020 edition of ICD-10-CM A84.9 became effective on October 1, 2019.
  • This is the American ICD-10-CM version of A84.9 - other international versions of ICD-10 A84.9 may differ.
The following code(s) above A84.9 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to A84.9:
  • A00-B99
    2020 ICD-10-CM Range A00-B99

    Certain infectious and parasitic diseases

    Includes
    • diseases generally recognized as communicable or transmissible
    Type 1 Excludes
    • certain localized infections - see body system-related chapters
    Type 2 Excludes
    • carrier or suspected carrier of infectious disease (Z22.-)
    • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
    • infectious and parasitic diseases specific to the perinatal period (P35-P39)
    • influenza and other acute respiratory infections (J00-J22)
    Use Additional
    • code to identify resistance to antimicrobial drugs (Z16.-)
    Certain infectious and parasitic diseases
  • A80-A89
    2020 ICD-10-CM Range A80-A89

    Viral and prion infections of the central nervous system

    Type 1 Excludes
    • postpolio syndrome (G14)
    • sequelae of poliomyelitis (B91)
    • sequelae of viral encephalitis (B94.1)
    Viral and prion infections of the central nervous system
  • A84
    ICD-10-CM Diagnosis Code A84

    Tick-borne viral encephalitis

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    Includes
    • tick-borne viral meningoencephalitis
    Tick-borne viral encephalitis
Approximate Synonyms
  • Tick-borne viral encephalitis
  • Viral encephalitis, tick borne
Clinical Information
  • 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)
ICD-10-CM A84.9 is grouped within Diagnostic Related Group(s) (MS-DRG v37.0):
  • 023 Craniotomy with major device implant or acute complex cns pdx with mcc or chemotherapy implant or epilepsy with neurostimulator
  • 024 Craniotomy with major device implant or acute complex cns pdx 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

Code History
  • 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

Diagnosis Index entries containing back-references to A84.9:
  • 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 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 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 Billable/Specific Code
        Type 1 Excludes
        • West nile virus with encephalitis (A92.31)
    • 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 Billable/Specific Code
    • virus, viral NOS B34.9
      ICD-10-CM Diagnosis Code B34.9

      Viral infection, unspecified

        2016 2017 2018 2019 2020 Billable/Specific Code
      Applicable To
      • Viremia NOS
      • encephalitis, tick-borne A84.9

ICD-10-CM Codes Adjacent To A84.9
A83.3 St Louis encephalitis
A83.4 Australian encephalitis
A83.5 California encephalitis
A83.6 Rocio virus disease
A83.8 Other mosquito-borne viral encephalitis
A83.9 Mosquito-borne viral encephalitis, unspecified
A84 Tick-borne viral encephalitis
A84.0 Far Eastern tick-borne encephalitis [Russian spring-summer encephalitis]
A84.1 Central European tick-borne encephalitis
A84.8 Other tick-borne viral encephalitis
A84.9 Tick-borne viral encephalitis, unspecified
A85 Other viral encephalitis, not elsewhere classified
A85.0 Enteroviral encephalitis
A85.1 Adenoviral encephalitis
A85.2 Arthropod-borne viral encephalitis, unspecified
A85.8 Other specified viral encephalitis
A86 Unspecified viral encephalitis
A87 Viral meningitis
A87.0 Enteroviral meningitis
A87.1 Adenoviral meningitis
A87.2 Lymphocytic choriomeningitis

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