Skip to main content
Call AIBook a demo

ICD-10-CM B05.0: Measles complicated by encephalitis

B05.0 is the billable ICD-10-CM code for measles complicated by encephalitis, in category B05 (Measles) of the Viral infections characterized by skin and mucous membrane lesions section. As a principal diagnosis it groups to MS-DRG 023 Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator, MS-DRG 024 Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC, MS-DRG 097 Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC (MDC 01 MDC 01: Diseases and Disorders of the Nervous System); or MS-DRG 791 Prematurity with Major Problems, MS-DRG 793 Full Term Neonate with Major Problems (MDC 15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period). As a secondary diagnosis it is an MCC, excluded with 22 principal diagnoses. 4 LCD billing and coding articles list it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
B05.0
billable FY2027 ICD-10-CM code
Category
B05 Measles
Chapter
1: Certain infectious and parasitic diseases (A00-B99)
CC/MCC (MS-DRG v44)
MCC
CMS-HCC V28
Not mapped
POA reporting
Required

Tabular list notes for B05.0

The tabular list has no notes on B05.0 itself; the notes below apply from its parent headings.

Inherited from B05 (Measles)

Includes
  • morbilli
Excludes1 (never coded together)
  • subacute sclerosing panencephalitis (A81.1)

MS-DRG grouping when B05.0 is the principal diagnosis

MS-DRG v44 groups for B05.0 as principal diagnosis
MDCMS-DRGs
01 MDC 01: Diseases and Disorders of the Nervous System023024097098099
15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period791793

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for B05.0 shows the full grouping logic.

CC/MCC status and inpatient edits

As a secondary diagnosis, B05.0 is an MCC under MS-DRG v44, unless the principal diagnosis is one of the 22 codes in its exclusion list. Check B05.0 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.

CMS-HCC V28 risk adjustment

B05.0 does not map to a payment HCC in the PY2027 CMS-HCC V28 model, so on its own it does not change a Medicare Advantage risk score.

LCD billing and coding articles that list B05.0

4 current Medicare billing and coding articles list B05.0 among the diagnoses that support medical necessity for the services they cover.

For teams evaluating QuickIntell software

Evaluate software for diagnosis coding review

If your team codes diagnoses at volume, review how QuickCode supports qualified coder review of documentation, specificity queries and the billing handoff. Confirm the code sets, settings and reviewer responsibilities during evaluation; a code reference is not a coding determination for a patient.

Evaluate QuickCode for diagnosis codingSee risk adjustment review
Book a software demoAsk about a software workflow

Optional software evaluation, not payer support or help with an individual claim. For coverage or payment decisions, use the official sources on this page. Do not include patient information in a demo booking or inquiry.

Frequently asked questions

What does ICD-10-CM B05.0 mean?

B05.0 means measles complicated by encephalitis. It is one of 8 billable codes under B05, measles.

What can't be coded with B05.0?

Excludes1 at B05: subacute sclerosing panencephalitis (A81.1). These are never reported together with B05.0.

Which MS-DRG does B05.0 group to?

As the principal diagnosis, B05.0 groups to MS-DRG 023 Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis with MCC or Antineoplastic Implant or Epilepsy with Neurostimulator, MS-DRG 024 Craniotomy with Major Device Implant or Acute Complex CNS Principal Diagnosis without MCC, MS-DRG 097 Non-Bacterial Infection of Nervous System Except Viral Meningitis with MCC (MDC 01 MDC 01: Diseases and Disorders of the Nervous System); or MS-DRG 791 Prematurity with Major Problems, MS-DRG 793 Full Term Neonate with Major Problems (MDC 15 MDC 15: Newborns and Other Neonates with Conditions Originating in Perinatal Period) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Is B05.0 a CC or MCC?

B05.0 is an MCC under MS-DRG v44; 22 principal diagnoses exclude it.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.