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
  • A23.0

    Brucellosis due to Brucella melitensis

  • A23.1

    Brucellosis due to Brucella abortus

  • A23.2

    Brucellosis due to Brucella suis

  • A23.3

    Brucellosis due to Brucella canis

  • A23.8

    Other brucellosis

  • A23.9

    Brucellosis, unspecified

  • A24.0

    Glanders

  • A24.1

    Acute and fulminating melioidosis

  • A24.2

    Subacute and chronic melioidosis

  • A24.3

    Other melioidosis

  • A24.9

    Melioidosis, unspecified

  • A25.0

    Spirillosis

  • A25.1

    Streptobacillosis

  • A25.9

    Rat-bite fever, unspecified

  • A26.0

    Cutaneous erysipeloid

  • A26.7

    Erysipelothrix sepsis

  • A26.8

    Other forms of erysipeloid

  • A26.9

    Erysipeloid, unspecified

  • A27.0

    Leptospirosis icterohemorrhagica

  • A27.81

    Aseptic meningitis in leptospirosis

  • A27.89

    Other forms of leptospirosis

  • A27.9

    Leptospirosis, unspecified

  • A28.0

    Pasteurellosis

  • A28.1

    Cat-scratch disease

  • A28.2

    Extraintestinal yersiniosis

  • A28.8

    Other specified zoonotic bacterial diseases, not elsewhere classified

  • A28.9

    Zoonotic bacterial disease, unspecified

  • A30.0

    Indeterminate leprosy

  • A30.1

    Tuberculoid leprosy

  • A30.2

    Borderline tuberculoid leprosy

  • A30.3

    Borderline leprosy

  • A30.4

    Borderline lepromatous leprosy

  • A30.5

    Lepromatous leprosy

  • A30.8

    Other forms of leprosy

  • A30.9

    Leprosy, unspecified

  • A31.0

    Pulmonary mycobacterial infection

  • A31.1

    Cutaneous mycobacterial infection

  • A31.2

    Disseminated mycobacterium avium-intracellulare complex (DMAC)

  • A31.8

    Other mycobacterial infections

  • A31.9

    Mycobacterial infection, unspecified

  • A32.0

    Cutaneous listeriosis

  • A32.11

    Listerial meningitis

  • A32.12

    Listerial meningoencephalitis

  • A32.7

    Listerial sepsis

  • A32.81

    Oculoglandular listeriosis

  • A32.82

    Listerial endocarditis

  • A32.89

    Other forms of listeriosis

  • A32.9

    Listeriosis, unspecified

  • A33

    Tetanus neonatorum

  • A34

    Obstetrical tetanus

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