A83
⚠ Non-billable
Mosquito-borne viral encephalitis
ICD-10-CM · FY2026 · Certain Infectious and Parasitic Diseases
Code
A83
System
ICD-10-CM
Billable
No — use specific code
Effective
FY2026
Chapter
Certain Infectious and Parasitic Diseases
Source
CMS / CDC NCHS
⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.
Official coding notes
From CMS's ICD-10-CM Tabular List.
Includes
- mosquito-borne viral meningoencephalitis
Excludes2 — not included here, but may code together
- Venezuelan equine encephalitis (A92.2)
- West Nile fever (A92.3-)
- West Nile virus (A92.3-)
Frequently asked questions
What is ICD-10 code A83?
ICD-10-CM code A83 represents Mosquito-borne viral encephalitis. It is a non-billable header code requiring a more specific subcategory in the Certain Infectious and Parasitic Diseases chapter, effective October 1, 2025 – September 30, 2026.
Is A83 billable?
No. A83 is a non-billable header. Select a more specific subcategory for claims submission.
What chapter is A83 in?
A83 belongs to the Certain Infectious and Parasitic Diseases chapter (A00–B99) of ICD-10-CM.
Related codes in the A83 category
A83.0
Japanese encephalitis
Billable
A83.1
Western equine encephalitis
Billable
A83.2
Eastern equine encephalitis
Billable
A83.3
St Louis encephalitis
Billable
A83.4
Australian encephalitis
Billable
A83.5
California encephalitis
Billable
A83.6
Rocio virus disease
Billable
A83.8
Other mosquito-borne viral encephalitis
Billable
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