A92.31 West Nile virus infection with encephalitis

The ICD-10-CM code for West Nile virus infection with encephalitis is A92.31 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

1: Certain infectious and parasitic diseases (A00-B99)

Section

A90-A99: Arthropod-borne viral fevers and viral hemorrhagic fevers (A90-A99)

Category A92

13 codes (11 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to A92.31:

• Virus, viral › West Nile (fever) › with › encephalitis
• Virus, viral › West Nile (fever) › with › encephalomyelitis
• Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › West › Nile (viral) › with › encephalomyelitis
• Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › West › Nile (viral) › with › encephalitis

Inclusion Terms

• West Nile encephalitis
• West Nile encephalomyelitis

U.S. Hospital Utilization

• An estimated 1,420 U.S. inpatient stays in 2023 included A92.31 among the documented diagnoses.
• 695 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

HIV Infections (TOC entry)

a. Human Immunodeficiency Virus (HIV) Infections .............................................................. 19

Infectious agents causing diseases in other chapters (TOC)

b. Infectious agents as the cause of diseases classified to other chapters ................................. 22

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)