Other and unspecified infectious diseases (B99) ICD-10-CM
The B99 code range covers other and unspecified infectious diseases with 3 ICD-10-CM diagnosis codes. 2 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Codes in the B99 Range 3 codes · 2 billable
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the B99 range.
Chronic Urticaria
Wheals (urticaria) and/or angioedema presented with daily symptoms lasting for more than 6 weeks. It may be classified into chronic spontaneous and chronic inducible urticaria depending on whether a specific trigger can be linked to the development of vascular reaction.
Cross Infection
Any infection which a patient contracts in a health-care institution.
Latent Infection
Delayed infection of the host by a dormant or inactive pathogen.
Mastectomy
Surgical procedure to remove one or both breasts.
Persistent Infection
Infection which lasts for a long period with continuous display of clinical features. Persistent infection arises due to inability of host cells to clear primary infections completely. When persistent infections are cleared so that infection symptoms are under control they are often referred to as chronic infections. LATENT INFECTIONS are infections in which manifestation of clinical symptoms appear later.
Seroma
Tumor-like sterile accumulation of serum in a tissue, organ, or cavity. It results from a tissue insult and is the product of tissue inflammation. It most commonly occurs following MASTECTOMY.
About the B99 Code Range
The ICD-10 code B99 is used for diagnoses involving infectious diseases that do not fit into more specific categories, covering both other and unspecified infectious conditions. It includes subcodes like B99.8 for other infectious diseases caused by unusual organisms and B99.9 for unspecified infectious diseases when precise identification is not available.
The section labeled B99.8 addresses infections caused by rare or less common pathogens, such as those stemming from algae, plants, or specific Prototheca species, which are sometimes called protothecosis. This code assists coders in accurately classifying infections that don't fall under typical bacterial, viral, or parasitic diseases but still require medical recognition. Meanwhile, B99.9 covers a broad range of unspecified infectious diseases, often used when the infection is confirmed but lacks a definitive cause or detailed clinical classification. This includes a wide spectrum of infections from localized abscesses and cellulitis to infections of prosthetic devices and organs. By recognizing the ICD-10 code for other and unspecified infectious diseases, healthcare professionals and coders can ensure appropriate documentation when infections are difficult to categorize or involve uncommon pathogens.
Questions About This Page
How many billable codes are in the B99 range?
Of the 3 codes in this range, 2 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the B99 range classify?
The range classifies other and unspecified infectious diseases. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
