ICD-10 A83
Non-Billable HeaderMosquito-borne viral encephalitis
About ICD-10-CM A83
ICD-10-CM code A83 represents Mosquito-borne viral encephalitis. This is a non-billable header code in the Infectious and Parasitic Diseases chapter (block A83). The 2026 edition of ICD-10-CM A83 became effective on October 1, 2025. Non-billable codes cannot be used as a primary or secondary diagnosis on a claim, use a more specific child code instead.
Type 2 Excludes
Not included here, the excluded code is not part of A83, but a patient may have both conditions at the same time. Both codes may be coded together when applicable.
- Venezuelan equine encephalitis (A92.2)
- West Nile fever (A92.3-)
- West Nile virus (A92.3-)
Includes
- mosquito-borne viral meningoencephalitis
Medicare LCD Coverage for A83
Local Coverage Determinations (LCDs) from CMS MACs that list A83 as a covered diagnosis.
This doesn't mean the code isn't covered, it means no MAC has issued a Local Coverage Determination naming this specific code. Coverage may still apply under National Coverage Determinations or general medical-necessity rules.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing A83.
2 Cigna
CPT Codes Commonly Billed with A83
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Codes Adjacent To A83
Other codes in section A80-A89 (Viral and prion infections of the central nervous system).
ICD-10 A83, Billing FAQ
Is ICD-10 code A83 billable? +
No, A83 is a non-billable header code. Use a more specific child code from block A83 when submitting claims.
What codes are Type 2 Excludes for A83? +
Type 2 Excludes (may be coded together when both conditions exist): Venezuelan equine encephalitis (A92.2); West Nile fever (A92.3-); West Nile virus (A92.3-)
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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