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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A88|
Other viral infections of central nervous system, not elsewhere classified
A88.0|
Enteroviral exanthematous fever [Boston exanthem]
A88.1|
Epidemic vertigo
A88.8|
Other specified viral infections of central nervous system
A89|
Unspecified viral infection of central nervous system
A90|
Dengue fever [classical dengue]
A91|
Dengue hemorrhagic fever
A92|
Other mosquito-borne viral fevers
A92.0|
Chikungunya virus disease
A92.1|
O'nyong-nyong fever
A92.2|
Venezuelan equine fever
A92.3|
West Nile virus infection
A92.30|
West Nile virus infection, unspecified
A92.31|
West Nile virus infection with encephalitis
A92.32|
West Nile virus infection with other neurologic manifestation
A92.39|
West Nile virus infection with other complications
A92.4|
Rift Valley fever
A92.5|
Zika virus disease
A92.8|
Other specified mosquito-borne viral fevers
A92.9|
Mosquito-borne viral fever, unspecified
A93|
Other arthropod-borne viral fevers, not elsewhere classified
A93.0|
Oropouche virus disease
A93.1|
Sandfly fever
A93.2|
Colorado tick fever
A93.8|
Other specified arthropod-borne viral fevers
A94|
Unspecified arthropod-borne viral fever
A95|
Yellow fever
A95.0|
Sylvatic yellow fever
A95.1|
Urban yellow fever
A95.9|
Yellow fever, unspecified
A96|
Arenaviral hemorrhagic fever
A96.0|
Junin hemorrhagic fever
A96.1|
Machupo hemorrhagic fever
A96.2|
Lassa fever
A96.8|
Other arenaviral hemorrhagic fevers
A96.9|
Arenaviral hemorrhagic fever, unspecified
A98|
Other viral hemorrhagic fevers, not elsewhere classified
A98.0|
Crimean-Congo hemorrhagic fever
A98.1|
Omsk hemorrhagic fever
A98.2|
Kyasanur Forest disease
A98.3|
Marburg virus disease
A98.4|
Ebola virus disease
A98.5|
Hemorrhagic fever with renal syndrome
A98.8|
Other specified viral hemorrhagic fevers
A99|
Unspecified viral hemorrhagic fever
B00|
Herpesviral [herpes simplex] infections
B00.0|
Eczema herpeticum
B00.1|
Herpesviral vesicular dermatitis
B00.2|
Herpesviral gingivostomatitis and pharyngotonsillitis
B00.3|
Herpesviral meningitis

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