2027 ICD-10-CM Diagnosis Code B05.1Measles complicated by meningitis
ICD-10-CM Codes›A00–B99›B00-B09›B05
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
B05.1 is a billable ICD-10-CM diagnosis code for measles complicated by meningitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 791, 793, 865 through 866. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 21 closely related codes. Coders also document this condition as measles of the central nervous system. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Meningitis and Viral infection.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Measles of the central nervous system
- Meningitis caused by Measles morbillivirus
- Meningitis caused by Paramyxovirus
- Post measles meningitis
- Sequela of infection caused by Morbillivirus
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to B05.1: its own notes plus those printed at B05 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.
- morbilli
- 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.
- Postmeasles meningitis
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
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 B05.1, its category, or a range that includes it.
Excludes1 3
These codes carry an Excludes1 note naming B05.1: they are not reported together with it, unless the two conditions are unrelated.
- A87 Viral meningitismeningitis due to measles virus (B05.1)
- G02 Meningitis in other infectious and parasitic diseases classified elsewheremeasles complicated by meningitis (B05.1)
- G04.01 Postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM)post measles myelitis (B05.1)
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Measles
a highly contagious infectious disease caused by morbillivirus, common among children but also seen in the nonimmune of any age, in which the virus enters the respiratory tract via droplet nuclei and multiplies in the epithelial cells, spreading throughout the mononuclear phagocyte system.
Patient EducationClinical
Measles
Measles is an infectious disease caused by a virus. It spreads easily from person to person. It causes a blotchy red rash. The rash often starts on the head and moves down the body. Other symptoms include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B05.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B05.1Overview
What is the ICD-10 code for measles complicated by meningitis?
The ICD-10-CM code for measles complicated by meningitis is B05.1 (sometimes written as B051). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is B05.1 (Measles) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report measles complicated by meningitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does B05.1 group to?
When measles complicated by meningitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 866, 865, with relative weights from 0.8691 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B05.1 a CC or MCC?
CMS lists B05.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 21 closely related codes in its exclusion list.
Can B05.1 be reported with A81.1?
Not as a rule. The Excludes1 note at B05, which applies to B05.1, lists "subacute sclerosing panencephalitis (A81.1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
