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
Infections and parasitic diseases in this chapter include intestinal infections, tuberculosis, viral diseases, fungal infections, and diseases caused by parasites. The chapter also includes lasting effects of these diseases and categories for bacterial and viral infectious agents.
The blocks separate diseases by cause, how some infections spread, and where some infections occur. Bacterial disease blocks distinguish infections associated with animals, infections transmitted mainly through sex, and other named groups. Viral blocks distinguish infections of the brain and spinal cord, fevers, infections with skin or mucous membrane lesions, hepatitis, and HIV disease. Separate blocks cover diseases caused by single-celled organisms and worms, other infestations, and other infectious diseases.
FY 2027 changes: The FY 2027 ICD-10-CM update, effective October 1, 2026, deleted 1 code in this chapter.
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 2027. 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 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
