A83.1

Billable

ChapterA00–B99

Ranksubcategory

Official Description

Western equine encephalitis

Metadata & Insights

•2026 ICD-10-CM Edition - Effective October 1, 2025.
•Billable/specific code (valid for reimbursement).
•Chapter 1: Certain Infectious and Parasitic Diseases (A00-B99).

General instructions are available for the parent sections:

View CH1 Notes View A80-A89 Notes View A83 Notes

Clinical Hierarchy

CH1Certain infectious and parasitic diseases (A00-B99)

A80-A89Viral and prion infections of the central nervous system (A80-A89)

A83Mosquito-borne viral encephalitis

A83.1Western equine encephalitis

Applicable Ancestor Context

The following parent sections contain instructions or notes that apply to A83.1:

categoryA83

Mosquito-borne viral encephalitis

View context instructions

blockA80-A89

Viral and prion infections of the central nervous system (A80-A89)

View context instructions

chapterCH1

Certain infectious and parasitic diseases (A00-B99)

View context instructions

Alphabetic Index Mentions

These are Diagnosis Index lookup paths that route to A83.1. Use them as entry terms for search, then confirm final coding instructions in the Tabular List and notes above.

4 raw paths

Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)3 unique routes

equine (acute) (infectious) (viral)

Encephalomyelitis1 unique routes

equine

Western→A83.1

MS-DRG Classification

2026 v43.1

This code is grouped within the following Diagnosis Related Group(s) for clinical reimbursement:

DRG 023

Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator

DRG 024

Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC

DRG 097

Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC

DRG 098

Non-Bacterial Infection of Nervous System Except Viral Meningitis with CC

DRG 099

Non-Bacterial Infection of Nervous System Except Viral Meningitis without CC/MCC

Cross Reference

Find Procedures (ICD-10-PCS)

Find surgical and procedural codes related to Western equine encephalitis.

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