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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