A83
Mosquito-borne viral encephalitis
A83 is a non-billable ICD-10-CM code category for mosquito-borne viral encephalitis. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are A83.0 Japanese encephalitis, A83.1 Western equine encephalitis, A83.2 Eastern equine encephalitis, A83.3 St Louis encephalitis and 5 more. Its coding notes include a Use additional code instruction, 3 Excludes1 entries and 8 Excludes2 entries.
Use additional code
Add the listed code as a secondary code, if known.
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (5 notes)
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
Includes
Further defines or gives examples of the content of the category.
- mosquito-borne viral meningoencephalitis
Also from chapter/block level (1 note)
- diseases generally recognized as communicable or transmissible
More specific codes under A83 9
- A83.0Japanese encephalitisBillable
- A83.1Western equine encephalitisBillable
- A83.2Eastern equine encephalitisBillable
- A83.3St Louis encephalitisBillable
- A83.4Australian encephalitisBillable
- A83.5California encephalitisBillable
- A83.6Rocio virus diseaseBillable
- A83.8Other mosquito-borne viral encephalitisBillable
- A83.9Mosquito-borne viral encephalitis, unspecifiedBillable