A84.9 — Tick-borne viral encephalitis, unspecified
A84.9 is a billable, specific ICD-10-CM code for tick-borne viral encephalitis, unspecified. It is valid for submission on a claim.
Risk adjustment
A84.9 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
A84.9 is named in 8 Medicare coverage policies — 8 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A56612Billing and Coding: CT of the Head
- A56771Billing and Coding: Special Electroencephalography
- A57204Billing and Coding: MRI and CT Scans of the Head and Neck
- A57206Billing and Coding: Lumbar MRI
How A84.9 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to A84.9.
- Encephalitis›tick-borne
- Infection, infected, infective›virus, viral NOS›encephalitis, tick-borne
- Encephalitis›viral, virus›arthropod-borne NEC›tick-borne
Related codes at this level
Codes that share A84. If A84.9 is not quite right, the correct code is usually one of these.
Questions about A84.9
- Is A84.9 a billable ICD-10-CM code?
- Yes. A84.9 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does A84.9 sit in the tabular list?
- Certain infectious and parasitic diseases (A00-B99), in the block Viral and prion infections of the central nervous system (A80-A89).