Chapter 1

A00–B99: Certain Infectious and Parasitic Diseases

Certain Infectious and Parasitic Diseases diagnostic classification updated for 2026.

Chapter Instructions

Includes
  • diseases generally recognized as communicable or transmissible
Excludes1(Not coded here. Use a different code.)
  • certain localized infections - see body system-related chapters
Excludes2(Not included here. Code separately if applicable.)
  • 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)
Use Additional Code
  • code to identify resistance to antimicrobial drugs (Z16.-)
Internal Codes
  • B97.19

    Other enterovirus as the cause of diseases classified elsewhere

  • B97.21

    SARS-associated coronavirus as the cause of diseases classified elsewhere

  • B97.29

    Other coronavirus as the cause of diseases classified elsewhere

  • B97.30

    Unspecified retrovirus as the cause of diseases classified elsewhere

  • B97.31

    Lentivirus as the cause of diseases classified elsewhere

  • B97.32

    Oncovirus as the cause of diseases classified elsewhere

  • B97.33

    Human T-cell lymphotrophic virus, type I [HTLV-I] as the cause of diseases classified elsewhere

  • B97.34

    Human T-cell lymphotrophic virus, type II [HTLV-II] as the cause of diseases classified elsewhere

  • B97.35

    Human immunodeficiency virus, type 2 [HIV 2] as the cause of diseases classified elsewhere

  • B97.39

    Other retrovirus as the cause of diseases classified elsewhere

  • B97.4

    Respiratory syncytial virus as the cause of diseases classified elsewhere

  • B97.5

    Reovirus as the cause of diseases classified elsewhere

  • B97.6

    Parvovirus as the cause of diseases classified elsewhere

  • B97.7

    Papillomavirus as the cause of diseases classified elsewhere

  • B97.81

    Human metapneumovirus as the cause of diseases classified elsewhere

  • B97.89

    Other viral agents as the cause of diseases classified elsewhere

  • B99.8

    Other infectious disease

  • B99.9

    Unspecified infectious disease

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