2027 ICD-10-CM Diagnosis Code B10.09Other human herpesvirus encephalitis
ICD-10-CM Codes›A00–B99›B10›B10
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Not Chronic
B10.09 is a billable ICD-10-CM diagnosis code for other human herpesvirus encephalitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 23 through 24, 97 through 99, 791, 793, 974 through 976. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 13 closely related codes. Coders also document this condition as disease caused by Human herpesvirus 8. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Encephalitis and Viral infection.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Disease caused by Human herpesvirus 8
- Human betaherpesvirus 7 encephalitis
- Human herpesvirus 8 encephalitis
- Infection by human herpesvirus 7
- Infection caused by Roseolovirus
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to B10.09: its own notes plus those printed at B10.0, B10, and Chapter 1. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- diseases generally recognized as communicable or transmissible
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Human herpesvirus 7 encephalitis
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- 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)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name B10.09, its category, or a range that includes it.
Excludes1 3
These codes carry an Excludes1 note naming B10.09: they are not reported together with it, unless the two conditions are unrelated.
- B00.4 Herpesviral encephalitisherpesviral encephalitis due to herpesvirus 6 and 7 (B10.01, B10.09)
- A85 Other viral encephalitis, not elsewhere classifiedencephalitis due to herpesvirus NEC (B10.0-) names B10.0-, which includes this code
- B00.4 Herpesviral encephalitisnon-simplex herpesviral encephalitis (B10.0-) names B10.0-, which includes this code
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) G04.90
due to herpesvirus 7 B10.09
specified NEC B10.09
Herpes, herpesvirus, herpetic B00.9
due to herpesvirus 7 B10.09
specified NEC B10.09
encephalitis B10.09
Meningoencephalitis See Also: Encephalitis; G04.90
due to herpesvirus 7 B10.09
specified NEC B10.09
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Encephalitis
Encephalitis is inflammation (swelling) of the brain. It can happen when an infection or medical condition that affects the brain activates your immune system. The inflammation can cause a wide range of symptoms. In extreme cases, it can lead to brain damage, stroke, or even death.
The full article covers:
- What is encephalitis?
- What causes encephalitis?
- Who is more likely to get encephalitis?
- What are the symptoms of encephalitis?
- How is encephalitis diagnosed?
- What are the treatments for encephalitis?
- Can encephalitis be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B10.09 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B10.09Overview
What is the ICD-10 code for other human herpesvirus encephalitis?
The ICD-10-CM code for other human herpesvirus encephalitis is B10.09 (sometimes written as B1009). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is B10.09 (Other human herpesvirus encephalitis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other human herpesvirus encephalitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does B10.09 group to?
When other human herpesvirus encephalitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 24, 98, 974, 976, 99, 975, 23, 97, with relative weights from 0.7879 to 5.7422 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B10.09 a CC or MCC?
CMS lists B10.09 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 13 closely related codes in its exclusion list.
What is the ICD-9 equivalent of B10.09?
Under the General Equivalence Mappings, other human herpesvirus encephalitis converts to ICD-9-CM 058.29 (human herpesvr encph NEC). The mapping is a direct match.
