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 Codes Billable Only

Internal Codes

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A19.0|
Acute miliary tuberculosis of a single specified site
A19.1|
Acute miliary tuberculosis of multiple sites
A19.2|
Acute miliary tuberculosis, unspecified
A19.8|
Other miliary tuberculosis
A19.9|
Miliary tuberculosis, unspecified
A20|
Plague
A20.0|
Bubonic plague
A20.1|
Cellulocutaneous plague
A20.2|
Pneumonic plague
A20.3|
Plague meningitis
A20.7|
Septicemic plague
A20.8|
Other forms of plague
A20.9|
Plague, unspecified
A21|
Tularemia
A21.0|
Ulceroglandular tularemia
A21.1|
Oculoglandular tularemia
A21.2|
Pulmonary tularemia
A21.3|
Gastrointestinal tularemia
A21.7|
Generalized tularemia
A21.8|
Other forms of tularemia
A21.9|
Tularemia, unspecified
A22|
Anthrax
A22.0|
Cutaneous anthrax
A22.1|
Pulmonary anthrax
A22.2|
Gastrointestinal anthrax
A22.7|
Anthrax sepsis
A22.8|
Other forms of anthrax
A22.9|
Anthrax, unspecified
A23|
Brucellosis
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|
Glanders and melioidosis
A24.0|
Glanders
A24.1|
Acute and fulminating melioidosis
A24.2|
Subacute and chronic melioidosis
A24.3|
Other melioidosis
A24.9|
Melioidosis, unspecified
A25|
Rat-bite fevers
A25.0|
Spirillosis
A25.1|
Streptobacillosis
A25.9|
Rat-bite fever, unspecified
A26|
Erysipeloid
A26.0|
Cutaneous erysipeloid
A26.7|
Erysipelothrix sepsis
A26.8|
Other forms of erysipeloid
A26.9|
Erysipeloid, unspecified

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