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)
  • certain localized infections - see body system-related chapters
Excludes2(Not included here)
  • 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
Browse by Section22 Sections
Internal Codes
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  • A00—

    Cholera

  • A00.0—

    Cholera due to Vibrio cholerae 01, biovar cholerae

  • A00.1—

    Cholera due to Vibrio cholerae 01, biovar eltor

  • A00.9—

    Cholera, unspecified

  • A01—

    Typhoid and paratyphoid fevers

  • A01.0—

    Typhoid fever

  • A01.00—

    Typhoid fever, unspecified

  • A01.01—

    Typhoid meningitis

  • A01.02—

    Typhoid fever with heart involvement

  • A01.03—

    Typhoid pneumonia

  • A01.04—

    Typhoid arthritis

  • A01.05—

    Typhoid osteomyelitis

  • A01.09—

    Typhoid fever with other complications

  • A01.1—

    Paratyphoid fever A

  • A01.2—

    Paratyphoid fever B

  • A01.3—

    Paratyphoid fever C

  • A01.4—

    Paratyphoid fever, unspecified

  • A02—

    Other salmonella infections

  • A02.0—

    Salmonella enteritis

  • A02.1—

    Salmonella sepsis

  • A02.2—

    Localized salmonella infections

  • A02.20—

    Localized salmonella infection, unspecified

  • A02.21—

    Salmonella meningitis

  • A02.22—

    Salmonella pneumonia

  • A02.23—

    Salmonella arthritis

  • A02.24—

    Salmonella osteomyelitis

  • A02.25—

    Salmonella pyelonephritis

  • A02.29—

    Salmonella with other localized infection

  • A02.8—

    Other specified salmonella infections

  • A02.9—

    Salmonella infection, unspecified

  • A03—

    Shigellosis

  • A03.0—

    Shigellosis due to Shigella dysenteriae

  • A03.1—

    Shigellosis due to Shigella flexneri

  • A03.2—

    Shigellosis due to Shigella boydii

  • A03.3—

    Shigellosis due to Shigella sonnei

  • A03.8—

    Other shigellosis

  • A03.9—

    Shigellosis, unspecified

  • A04—

    Other bacterial intestinal infections

  • A04.0—

    Enteropathogenic Escherichia coli infection

  • A04.1—

    Enterotoxigenic Escherichia coli infection

  • A04.2—

    Enteroinvasive Escherichia coli infection

  • A04.3—

    Enterohemorrhagic Escherichia coli infection

  • A04.4—

    Other intestinal Escherichia coli infections

  • A04.5—

    Campylobacter enteritis

  • A04.6—

    Enteritis due to Yersinia enterocolitica

  • A04.7—

    Enterocolitis due to Clostridium difficile

  • A04.71—

    Enterocolitis due to Clostridium difficile, recurrent

  • A04.72—

    Enterocolitis due to Clostridium difficile, not specified as recurrent

  • A04.8—

    Other specified bacterial intestinal infections

  • A04.9—

    Bacterial intestinal infection, unspecified

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