A83.3 is the authoritative medical code for St Louis encephalitis. This classification is used in medical billing and clinical recording to specify the clinical criteria for st louis encephalitis (ICD-10-CM A83.3), ensuring healthcare documentation aligns with 2026 federal coding standards.
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Official Registry Overview & Definition
St Louis encephalitis is a billable ICD-10-CM diagnosis code A83.3. Includes: mosquito-borne viral meningoencephalitis. Excludes1 (not coded here): postpolio syndrome G14; sequelae of poliomyelitis B91; sequelae of viral encephalitis B94.1. Excludes2 (not included here): Venezuelan equine encephalitis A92.2; West Nile fever A92.3-; West Nile virus A92.3-.
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for A83.3 in the official ICD-10-CM tabular list.
Includes
Conditions the official ICD-10-CM tabular list includes under this code.
- mosquito-borne viral meningoencephalitis
Excludes1 — Not Coded Here
Conditions that can never be reported with this code; the two are mutually exclusive.
- postpolio syndrome G14
- sequelae of poliomyelitis B91
- sequelae of viral encephalitis B94.1
Excludes2 — Not Included Here
Conditions not covered by this code, but which may be reported alongside it when both are present.
- Venezuelan equine encephalitis A92.2
- West Nile fever A92.3-
- West Nile virus A92.3-
Frequently Asked Questions (FAQ) & Clinical Guidance
What can't be coded together with A83.3?
Per Excludes1 instructions, A83.3 must not be reported with: postpolio syndrome (G14); sequelae of poliomyelitis (B91); sequelae of viral encephalitis (B94.1).
Can A83.3 be reported alongside related conditions?
Per Excludes2 instructions, A83.3 and the following may both be reported when both are present: Venezuelan equine encephalitis (A92.2); West Nile fever (A92.3-); West Nile virus (A92.3-).
Codes in This Family (9)
Official ICD-10-CM classifications in the same code family as A83.3, with their registry titles.
- A83 — Mosquito-borne viral encephalitis
- A83.0 — Japanese encephalitis
- A83.1 — Western equine encephalitis
- A83.2 — Eastern equine 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
Indexed Clinical Terms (4)
Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code.
- Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute), St. Louis
- Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute), type, C
- Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute), viral, virus, arthropod-borne NEC, mosquito-borne, St. Louis
- Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute), viral, virus, arthropod-borne NEC, mosquito-borne, type C
Related Codes & Numerical Sequence (Crawl Map)
Search engines and indexers are advised to traverse adjacent medical codes in this sub-chapter range to find correlated diagnoses or therapeutic procedures: