2027 ICD-10-CM Diagnosis Code B26.2Mumps encephalitis
ICD-10-CM Codes›A00–B99›B25-B34›B26
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Not Chronic
B26.2 is a billable ICD-10-CM diagnosis code for mumps 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. 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 23 closely related codes. Coders also document this condition as meningitis caused by mumps virus. 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.
- Meningitis caused by mumps virus
- Meningitis caused by Paramyxovirus
- Meningoencephalitis caused by virus
- Mumps encephalitis
- Mumps meningoencephalitis
- Paramyxoviridae encephalitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to B26.2: its own notes plus those printed at B26 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.
- epidemic parotitis
- infectious parotitis
- diseases generally recognized as communicable or transmissible
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 B26.2, its category, or a range that includes it.
Applicable To 1
These notes mention B26.2.
- O98.5 Other viral diseases complicating pregnancy, childbirth and the puerperium
Excludes1 4
These codes carry an Excludes1 note naming B26.2: they are not reported together with it, unless the two conditions are unrelated.
- A85 Other viral encephalitis, not elsewhere classifiedencephalitis due to mumps virus (B26.2)
- G05 Encephalitis, myelitis and encephalomyelitis in diseases classified elsewheremumps encephalitis, myelitis and encephalomyelitis (B26.2)
- K11.2 Sialoadenitisepidemic parotitis (B26.-) names B26.-, which includes this code
- K11.2 Sialoadenitismumps (B26.-) names B26.-, 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
mumps B26.2
Meningoencephalitis See Also: Encephalitis; G04.90
encephalitis B26.2
meningoencephalitis B26.2
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Mumps
an acute infectious disease caused by rubulavirus, spread by direct contact, airborne droplet nuclei, fomites contaminated by infectious saliva, and perhaps urine, and usually seen in children under the age of 15, although adults may also be affected. (from dorland, 28th ed)
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 B26.2 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B26.2Overview
What is the ICD-10 code for mumps encephalitis?
The ICD-10-CM code for mumps encephalitis is B26.2 (sometimes written as B262). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is B26.2 (Mumps) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report mumps encephalitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does B26.2 group to?
When mumps encephalitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 24, 98, 99, 23, 97, with relative weights from 1.5249 to 5.7422 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B26.2 a CC or MCC?
CMS lists B26.2 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 23 closely related codes in its exclusion list.
What is the ICD-9 equivalent of B26.2?
Under the General Equivalence Mappings, mumps encephalitis converts to ICD-9-CM 072.2 (mumps encephalitis). The mapping is a direct match.
