A83.3 – St Louis encephalitis

ICD-10-CM 2027 diagnosis code · Viral and prion infections of the central nervous system

Billable code

ICD-10-CM code A83.3

Code: A83.3 (claims format: A833)
Description: St Louis encephalitis
Billable: Yes – valid for HIPAA-covered transactions
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 1. Certain infectious and parasitic diseases (A00-B99)
Block: A80-A89 Viral and prion infections of the central nervous system
Parent codes: A83

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

A83 – Mosquito-borne viral encephalitis

Includes:

mosquito-borne viral meningoencephalitis

Excludes2 (not included here):

Venezuelan equine encephalitis (A92.2)
West Nile fever (A92.3-)
West Nile virus (A92.3-)

Block A80-A89

Excludes1 (not coded here):

postpolio syndrome (G14)
sequelae of poliomyelitis (B91)
sequelae of viral encephalitis (B94.1)

Index terms for A83.3

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in A83

A83.0 – Japanese encephalitisBillable
A83.1 – Western equine encephalitisBillable
A83.2 – Eastern equine encephalitisBillable
A83.4 – Australian encephalitisBillable
A83.5 – California encephalitisBillable
A83.6 – Rocio virus diseaseBillable
A83.8 – Other mosquito-borne viral encephalitisBillable
A83.9 – Mosquito-borne viral encephalitis, unspecifiedBillable

Frequently asked questions

What is ICD-10 code A83.3?

A83.3 is the ICD-10-CM code for st Louis encephalitis, in the block A80-A89 (Viral and prion infections of the central nervous system).

Is A83.3 a billable code?

Yes. A83.3 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does A83.3 belong to?

It belongs to category A83 – Mosquito-borne viral encephalitis.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.