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ICD-10-CM chapter 1 · A00-B99

Certain infectious and parasitic diseases

About chapter 1

Chapter 1 (A00-B99) contains 167 categories and 1,068 billable codes for FY2027. No codes here changed in the FY2027 update. 150 codes are MCCs and 609 are CCs when reported as secondary diagnoses.

22 code blocks

Chapter notes

Includes
  • diseases generally recognized as communicable or transmissible
Excludes2
  • carrier or suspected carrier of infectious disease (Z22.-)
  • certain localized infections - see body system-related chapters
  • 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)
Use additional code
  • code to identify resistance to antimicrobial drugs (Z16.-)