2026 ICD-10-CM Diagnosis Code B64Unspecified protozoal disease

ICD-10-CM Codes›A00–B99›B50-B64›B64

ICD-10-CM B64
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

B64 is a billable ICD-10-CM diagnosis code for unspecified protozoal disease. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 867 through 869. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Parasitic, other specified and unspecified infections.

Code Identity

ICD-10-CM Code
B64
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified protozoal disease
Chapter
B50-B64
Protozoal diseases

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionB50-B64Protozoal diseases
CategoryB64Unspecified protozoal disease
This CodeB64Unspecified protozoal disease

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cardiovascular abnormality due to infective myocarditis
  • Dilated cardiomyopathy due to infectious disease
  • Dilated cardiomyopathy due to parasitic myocarditis
  • Dilated cardiomyopathy due to protozoan myocarditis
  • Encephalitis caused by protozoa
  • Infective ulcer of esophagus
  • Parasitic conjunctivitis
  • Parasitic disease in mother complicating pregnancy, childbirth AND/OR puerperium
  • Parasitic infection causing ulcer of esophagus
  • Parasitic infection of lacrimal gland
  • Parasitic myocarditis
  • Parasitic myositis
  • Protozoal conjunctivitis
  • Protozoal corneal ulcer
  • Protozoal dacryoadenitis
  • Protozoal disease complicating pregnancy childbirth and the puerperium
  • Protozoal esophagitis
  • Protozoal infestation of skin
  • Protozoal myelitis
  • Protozoal myositis
  • Protozoal ulcer of esophagus
  • Protozoan infection
  • Protozoan myocarditis

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.

    • Disease, diseased
      • protozoal
    • Infection, infected, infective(opportunistic)
      • protozoal NEC
    • Infestation
      • protozoal NEC
    • Protozoal
      • disease

Clinical ClassificationClinical

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

CCSR INF009
Parasitic, other specified and unspecified infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Parasitic Diseases

Parasites are living things that use other living things - like your body - for food and a place to live. You can get them from contaminated food or water, a bug bite, or sexual contact. Some parasitic diseases are easily treated and some are not.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert B64 to ICD-9-CMHistory

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

ICD-9-CM
088.9 Arthropod-borne dis NOS
Approximate The match is approximate rather than exact.
ICD-9-CM
136.9 Infect/parasite dis NOS
Approximate The match is approximate rather than exact.

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 B64Overview

Is B64 (Unspecified protozoal disease) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified protozoal disease on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does B64 group to?

When unspecified protozoal disease is the principal diagnosis on an inpatient stay, it groups to MS-DRG 867, 868, 869, with relative weights from 0.7297 to 2.0932 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of B64?

Under the General Equivalence Mappings, unspecified protozoal disease converts to ICD-9-CM 088.9 (arthropod-borne dis NOS) and 136.9 (infect/parasite dis NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.