2026 ICD-10-CM Diagnosis Code Z86.61Personal history of infections of the central nervous system

ICD-10-CM Codes›Z00–Z99›Z77-Z99›Z86

ICD-10-CM Z86.61
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z86.61 is a billable ICD-10-CM diagnosis code for personal history of infections of the central nervous system. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. Coders also document this condition as H/O: encephalitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Personal history of other disease.

Code Identity

ICD-10-CM Code
Z86.61
Billable Status
Yes — Valid for Submission
Code Describes
Personal history of infections of the central nervous system
Short Description
Personal history of infections of the central nervous system
Same as the full description in the CMS dataset.
Parent Code
Z86.6
Personal history of diseases of the nervous system and sense organs

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ77-Z99Persons with potential health hazards related to family and personal history and certain conditions influencing health status
CategoryZ86Personal history of certain other diseases
This CodeZ86.61Personal history of infections of the central nervous system

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z86.61.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Present on Admission (POA)Billing

Z86.61 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • H/O: encephalitis
  • H/O: meningitis
  • History of infectious disease of central nervous system
  • History of listeria meningitis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Personal history of encephalitis
  • Personal history of meningitis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • History
      • personal (of)
        • encephalitis
    • History
      • personal (of)
        • infection NEC
          • central nervous system
    • History
      • personal (of)
        • meningitis

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR FAC030
Personal history of other disease
Default principal diagnosis: inpatient No · outpatient Yes

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 Z86.61 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
V12.42 Personl hx infection CNS
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Z86.61Overview

Is Z86.61 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report personal history of infections of the central nervous system on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can Z86.61 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because personal history of infections of the central nervous system describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z86.61 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for personal history of infections of the central nervous system on inpatient claims.

What is the ICD-9 equivalent of Z86.61?

Under the General Equivalence Mappings, personal history of infections of the central nervous system converts to ICD-9-CM V12.42 (personl hx infection CNS). The mapping is a direct match.