ICD-10-CM Code For Other And Unspecified Infectious Diseases: Group Overview

The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group B99 includes miscellaneous and unspecified infectious diseases not classified elsewhere, covering infections by various pathogens when specific organism or site codes are not applicable. These ICD-10-CM diagnosis codes are used to document clinical scenarios such as systemic infections of unclear etiology, unspecified infectious complications, or when organism confirmation is pending, capturing disease severity, organ involvement, or clinical complexity relevant to this group. Accurate coding within the ICD-10-CM B99 group supports proper claim adjudication, complete clinical documentation, and appropriate reimbursement.

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ICD-10-CM B99: Other And Unspecified Infectious Diseases Overview

The ICD-10-CM B99 group includes other and unspecified infectious diseases that do not have a more specific category elsewhere in the classification. These codes cover systemic or localized infections caused by various organisms when the pathogen or exact diagnosis is not otherwise specified. Accurate coding matters for reimbursement because it supports claim processing and reflects the clinical complexity of infection-related care.

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ICD-10-CM Code For Other And Unspecified Infectious Diseases: Group Overview

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ICD-10-CM B99: Other And Unspecified Infectious Diseases Overview

When to Use

Use a code from this group when a patient has an infection documented as other or unspecified and no more specific ICD-10-CM code applies. These codes are also appropriate when organism identification is pending or when documentation lacks detail to assign a more specific infectious disease code.

ICD-10-CM Codes

2 rows

ICD-10-CM Code	Description
B99.8	Other infectious disease
B99.9	Unspecified infectious disease

DRG Codes

6 rows

DRG Code	Description
867	Other Infectious and Parasitic Diseases Diagnoses with MCC
868	Other Infectious and Parasitic Diseases Diagnoses with CC
869	Other Infectious and Parasitic Diseases Diagnoses without CC/MCC
974	HIV with Major Related Condition with MCC
975	HIV with Major Related Condition with CC
976	HIV with Major Related Condition without CC/MCC

Typical Clinical Scenarios

An adult presents to urgent care with acute fever, malaise, and a generalized viral syndrome after recent travel, but laboratory testing and clinical evaluation fail to identify a specific infectious agent; the provider documents a nonspecific infectious disease pending further workup or when no definitive pathogen is found. Typical codes: B99.9
A hospitalized elderly patient with multiple comorbidities develops signs of infection (fever, leukocytosis) and clinicians suspect an unusual or unspecified infectious process that does not fit a specific pathogen category; the team documents an unspecified other infectious disease as a contributor to the admission when targeted testing is inconclusive. Typical codes: B99.8, B99.9
A patient is seen in follow-up for sequelae of a previously treated infection where residual symptoms persist but repeat testing is negative for known organisms; the clinician records an unspecified post-infectious or other infectious condition to capture ongoing management of infection-related symptoms. Typical codes: B99.8

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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When to Use

ICD-10-CM Codes

2 rows

ICD-10-CM Code	Description
B99.8	Other infectious disease
B99.9	Unspecified infectious disease

DRG Codes

6 rows

DRG Code	Description
867	Other Infectious and Parasitic Diseases Diagnoses with MCC
868	Other Infectious and Parasitic Diseases Diagnoses with CC
869	Other Infectious and Parasitic Diseases Diagnoses without CC/MCC
974	HIV with Major Related Condition with MCC
975	HIV with Major Related Condition with CC
976	HIV with Major Related Condition without CC/MCC

Typical Clinical Scenarios

An adult presents to urgent care with acute fever, malaise, and a generalized viral syndrome after recent travel, but laboratory testing and clinical evaluation fail to identify a specific infectious agent; the provider documents a nonspecific infectious disease pending further workup or when no definitive pathogen is found. Typical codes: B99.9
A hospitalized elderly patient with multiple comorbidities develops signs of infection (fever, leukocytosis) and clinicians suspect an unusual or unspecified infectious process that does not fit a specific pathogen category; the team documents an unspecified other infectious disease as a contributor to the admission when targeted testing is inconclusive. Typical codes: B99.8, B99.9
A patient is seen in follow-up for sequelae of a previously treated infection where residual symptoms persist but repeat testing is negative for known organisms; the clinician records an unspecified post-infectious or other infectious condition to capture ongoing management of infection-related symptoms. Typical codes: B99.8

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

ICD-10-CM Code For Other And Unspecified Infectious Diseases: Group Overview

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ICD-10-CM B99: Other And Unspecified Infectious Diseases Overview

ICD-10-CM Code For Other And Unspecified Infectious Diseases: Group Overview

Sign up for ICD-10-CM Code For Other And Unspecified Infectious Diseases: Group Overview policy alerts

ICD-10-CM B99: Other And Unspecified Infectious Diseases Overview

When to Use

ICD-10-CM Codes

DRG Codes

Typical Clinical Scenarios

When should I use `B99` codes for documentation?

What specific codes are included in the `B99` group?

How do `B99` codes affect reimbursement and claims?

Which related DRGs commonly map to infections coded in `B99`?

Can `B99` codes be used when organism confirmation is pending?

References

When to Use

ICD-10-CM Codes

DRG Codes

Typical Clinical Scenarios

When should I use `B99` codes for documentation?

What specific codes are included in the `B99` group?

How do `B99` codes affect reimbursement and claims?

Which related DRGs commonly map to infections coded in `B99`?

Can `B99` codes be used when organism confirmation is pending?

References