ICD-10 B00.4
Billable / Specific MCCHerpesviral encephalitis
About ICD-10-CM B00.4
ICD-10-CM code B00.4 represents Herpesviral encephalitis. This is a billable/specific code in the Infectious and Parasitic Diseases chapter (block B00). The 2026 edition of ICD-10-CM B00.4 became effective on October 1, 2025.
Coding Tips for B00.4
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
B00.4 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under B00.4. Per CMS ICD-10-CM Tabular 2026.
- Herpesviral meningoencephalitis
- Simian B disease
Type 1 Excludes
Pure excludes, these codes can never be coded together with B00.4. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- herpesviral encephalitis due to herpesvirus 6 and 7 (B10.01, B10.09)
- non-simplex herpesviral encephalitis (B10.0-)
Inpatient DRG Impact, MCC
codes Herpesviral encephalitis. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for B00.4
Local Coverage Determinations (LCDs) from CMS MACs that list B00.4 as a covered diagnosis.
Showing top 10 of 593 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing B00.4.
1 Cigna
5 Medicare
CPT Codes Commonly Billed with B00.4
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 95929 CMS LCD: Billing and Coding: Neurophysiology Evoked Potentials (NEPs) CMS LCD
- 92651 CMS LCD: Billing and Coding: Neurophysiology Evoked Potentials (NEPs) CMS LCD
- 92653 CMS LCD: Billing and Coding: Neurophysiology Evoked Potentials (NEPs) CMS LCD
- 95928 CMS LCD: Billing and Coding: Neurophysiology Evoked Potentials (NEPs) CMS LCD
- 95930 CMS LCD: Billing and Coding: Neurophysiology Evoked Potentials (NEPs) CMS LCD
- 92652 CMS LCD: Billing and Coding: Neurophysiology Evoked Potentials (NEPs) CMS LCD
- 95939 CMS LCD: Billing and Coding: Neurophysiology Evoked Potentials (NEPs) CMS LCD
- Q9953 CMS LCD: Billing and Coding: Lumbar MRI CMS LCD
- A9585 CMS LCD: Billing and Coding: Lumbar MRI CMS LCD
Convert B00.4 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| B00.4 | 0543 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To B00.4
Other codes in section B00-B09 (Viral infections characterized by skin and mucous membrane lesions).
ICD-10 B00.4, Billing FAQ
Is ICD-10 code B00.4 billable? +
Yes, B00.4 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to B00.4? +
ICD-10 B00.4 includes: Herpesviral meningoencephalitis; Simian B disease.
What codes are Type 1 Excludes for B00.4? +
Type 1 Excludes (never code together with B00.4): herpesviral encephalitis due to herpesvirus 6 and 7 (B10.01, B10.09); non-simplex herpesviral encephalitis (B10.0-)
Is B00.4 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with B00.4? +
Procedures frequently paired with B00.4 include: 95929, 92651, 92653, 95928, 95930.
What ICD-9 codes does B00.4 map to? +
Per CMS GEMs, B00.4 maps to ICD-9 codes: 0543. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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