Certain infectious and parasitic diseases (A00–B99) ICD-10-CM
Chapter 1 of the ICD-10-CM classification spans codes A00–B99 and contains 1,309 diagnosis codes for certain infectious and parasitic diseases, of which 1,068 are billable. The chapter is organized into 22 sections listed below, each linking to its code ranges and individual codes.
Chapter Coding Notes
Includes: diseases generally recognized as communicable or transmissible Use additional code to identify resistance to antimicrobial drugs (Z16.-)
Excludes1: certain localized infections - see body system-related chapters
Excludes2: carrier or suspected carrier of infectious disease (Z22.-), 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).
Sections in This Chapter 22 ranges · 1,309 codes
The info icon previews the code ranges inside each row and its instructional notations from the official Tabular List.
About Chapter 1
Chapter 1 of the ICD-10-CM classification covers certain infectious and parasitic diseases, which are identified using codes from A00 to B99. These codes are used to classify a wide range of illnesses caused by bacteria, viruses, parasites, and other infectious agents.
This chapter includes infections such as intestinal infectious diseases, tuberculosis, viral hepatitis, human immunodeficiency virus (HIV) infection, and malaria. It also addresses diseases resulting from parasitic infestations and certain other infections that can affect multiple organ systems. Healthcare providers and medical coders use these codes to accurately describe conditions involving infectious agents for diagnosis, treatment, and monitoring purposes. The range ensures precise classification of infectious diseases that may have significant public health implications, supporting effective communication and management within clinical and epidemiological settings.
Questions About This Page
How many codes are in the A00-B99 range?
The A00-B99 range contains 1,309 ICD-10-CM diagnosis codes in FY 2026. 1,068 of them are billable, and the rest are category headers that organize the chapter.
What conditions does A00-B99 cover?
The range covers certain infectious and parasitic diseases. The sections listed above break it into groups of related conditions, and each one links to its own page with the full code list.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
