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
  • B27.00

    Gammaherpesviral mononucleosis without complication

  • B27.01

    Gammaherpesviral mononucleosis with polyneuropathy

  • B27.02

    Gammaherpesviral mononucleosis with meningitis

  • B27.09

    Gammaherpesviral mononucleosis with other complications

  • B27.10

    Cytomegaloviral mononucleosis without complications

  • B27.11

    Cytomegaloviral mononucleosis with polyneuropathy

  • B27.12

    Cytomegaloviral mononucleosis with meningitis

  • B27.19

    Cytomegaloviral mononucleosis with other complication

  • B27.80

    Other infectious mononucleosis without complication

  • B27.81

    Other infectious mononucleosis with polyneuropathy

  • B27.82

    Other infectious mononucleosis with meningitis

  • B27.89

    Other infectious mononucleosis with other complication

  • B27.90

    Infectious mononucleosis, unspecified without complication

  • B27.91

    Infectious mononucleosis, unspecified with polyneuropathy

  • B27.92

    Infectious mononucleosis, unspecified with meningitis

  • B27.99

    Infectious mononucleosis, unspecified with other complication

  • B30.0

    Keratoconjunctivitis due to adenovirus

  • B30.1

    Conjunctivitis due to adenovirus

  • B30.2

    Viral pharyngoconjunctivitis

  • B30.3

    Acute epidemic hemorrhagic conjunctivitis (enteroviral)

  • B30.8

    Other viral conjunctivitis

  • B30.9

    Viral conjunctivitis, unspecified

  • B33.0

    Epidemic myalgia

  • B33.1

    Ross River disease

  • B33.20

    Viral carditis, unspecified

  • B33.21

    Viral endocarditis

  • B33.22

    Viral myocarditis

  • B33.23

    Viral pericarditis

  • B33.24

    Viral cardiomyopathy

  • B33.3

    Retrovirus infections, not elsewhere classified

  • B33.4

    Hantavirus (cardio)-pulmonary syndrome [HPS] [HCPS]

  • B33.8

    Other specified viral diseases

  • B34.0

    Adenovirus infection, unspecified

  • B34.1

    Enterovirus infection, unspecified

  • B34.2

    Coronavirus infection, unspecified

  • B34.3

    Parvovirus infection, unspecified

  • B34.4

    Papovavirus infection, unspecified

  • B34.8

    Other viral infections of unspecified site

  • B34.9

    Viral infection, unspecified

  • B35.0

    Tinea barbae and tinea capitis

  • B35.1

    Tinea unguium

  • B35.2

    Tinea manuum

  • B35.3

    Tinea pedis

  • B35.4

    Tinea corporis

  • B35.5

    Tinea imbricata

  • B35.6

    Tinea cruris

  • B35.8

    Other dermatophytoses

  • B35.9

    Dermatophytosis, unspecified

  • B36.0

    Pityriasis versicolor

  • B36.1

    Tinea nigra

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