1. ICD-10-CM Codes
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2. A00-B99
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3. A80-A89
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4. A83-
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5. 2023 ICD-10-CM Diagnosis Code A83.3

2023 ICD-10-CM Diagnosis Code A83.3

St Louis encephalitis

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

• A83.3 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 A83.3 became effective on October 1, 2022.
• This is the American ICD-10-CM version of A83.3 - other international versions of ICD-10 A83.3 may differ.

• St. Louis encephalitis virus infection

• A viral encephalitis caused by the st. Louis encephalitis virus (encephalitis virus, st. Louis), a flavivirus. It is transmitted to humans and other vertebrates primarily by mosquitoes of the genus culex. The primary animal vectors are wild birds and the disorder is endemic to the midwestern and southeastern United States. Infections may be limited to an influenza-like illness or present as an aseptic meningitis or encephalitis. Clinical manifestations of the encephalitic presentation may include seizures, lethargy, myoclonus, focal neurologic signs, coma, and death. (from Adams et al., Principles of Neurology, 6th ed, p750)
• Brain infection caused by the st. Louis encephalitis virus

• 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 A83.3 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
  • type
    • C A83.3
  • 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)
      • mosquito-borne A83.9
        ICD-10-CM Diagnosis Code A83.9

        Mosquito-borne viral encephalitis, unspecified

        2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
        • St. Louis A83.3
        • type C A83.3
  • St. Louis A83.3

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