All ICD10 Codes
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.-)
All CodesBillable Only
Internal Codes
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  • A41.4|

    Sepsis due to anaerobes

  • A41.50|

    Gram-negative sepsis, unspecified

  • A41.51|

    Sepsis due to Escherichia coli [E. coli]

  • A41.52|

    Sepsis due to Pseudomonas

  • A41.53|

    Sepsis due to Serratia

  • A41.54|

    Sepsis due to Acinetobacter baumannii

  • A41.59|

    Other Gram-negative sepsis

  • A41.81|

    Sepsis due to Enterococcus

  • A41.89|

    Other specified sepsis

  • A41.9|

    Sepsis, unspecified organism

  • A42.0|

    Pulmonary actinomycosis

  • A42.1|

    Abdominal actinomycosis

  • A42.2|

    Cervicofacial actinomycosis

  • A42.7|

    Actinomycotic sepsis

  • A42.81|

    Actinomycotic meningitis

  • A42.82|

    Actinomycotic encephalitis

  • A42.89|

    Other forms of actinomycosis

  • A42.9|

    Actinomycosis, unspecified

  • A43.0|

    Pulmonary nocardiosis

  • A43.1|

    Cutaneous nocardiosis

  • A43.8|

    Other forms of nocardiosis

  • A43.9|

    Nocardiosis, unspecified

  • A44.0|

    Systemic bartonellosis

  • A44.1|

    Cutaneous and mucocutaneous bartonellosis

  • A44.8|

    Other forms of bartonellosis

  • A44.9|

    Bartonellosis, unspecified

  • A46|

    Erysipelas

  • A48.0|

    Gas gangrene

  • A48.1|

    Legionnaires' disease

  • A48.2|

    Nonpneumonic Legionnaires' disease [Pontiac fever]

  • A48.3|

    Toxic shock syndrome

  • A48.4|

    Brazilian purpuric fever

  • A48.51|

    Infant botulism

  • A48.52|

    Wound botulism

  • A48.8|

    Other specified bacterial diseases

  • A49.01|

    Methicillin susceptible Staphylococcus aureus infection, unspecified site

  • A49.02|

    Methicillin resistant Staphylococcus aureus infection, unspecified site

  • A49.1|

    Streptococcal infection, unspecified site

  • A49.2|

    Hemophilus influenzae infection, unspecified site

  • A49.3|

    Mycoplasma infection, unspecified site

  • A49.8|

    Other bacterial infections of unspecified site

  • A49.9|

    Bacterial infection, unspecified

  • A50.01|

    Early congenital syphilitic oculopathy

  • A50.02|

    Early congenital syphilitic osteochondropathy

  • A50.03|

    Early congenital syphilitic pharyngitis

  • A50.04|

    Early congenital syphilitic pneumonia

  • A50.05|

    Early congenital syphilitic rhinitis

  • A50.06|

    Early cutaneous congenital syphilis

  • A50.07|

    Early mucocutaneous congenital syphilis

  • A50.08|

    Early visceral congenital syphilis

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