2026 ICD-10-CM Diagnosis Code A91Dengue hemorrhagic fever

ICD-10-CM Codes›A00–B99›A90-A99›A91

ICD-10-CM A91
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A91 is a billable ICD-10-CM diagnosis code for dengue hemorrhagic fever. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 865 through 866. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Viral infection.

Code Identity

ICD-10-CM Code
A91
Billable Status
Yes — Valid for Submission
Code Describes
Dengue hemorrhagic fever
Chapter
A90-A99
Arthropod-borne viral fevers and viral hemorrhagic fevers

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA90-A99Arthropod-borne viral fevers and viral hemorrhagic fevers
CategoryA91Dengue hemorrhagic fever
This CodeA91Dengue hemorrhagic fever

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Dengue
  • Dengue hemorrhagic fever
  • Dengue hemorrhagic fever, grade I
  • Dengue hemorrhagic fever, grade II
  • Dengue hemorrhagic fever, grade III
  • Dengue hemorrhagic fever, grade IV
  • Dengue shock syndrome

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Bangkok hemorrhagic fever
    • Dengue(classical) (fever)
      • hemorrhagic
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Bangkok hemorrhagic
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • dengue (virus)
        • hemorrhagic
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • hemorrhagic (arthropod-borne) NOS
        • Bangkok
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • hemorrhagic (arthropod-borne) NOS
        • dengue (virus)
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • hemorrhagic (arthropod-borne) NOS
        • Philippine
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • hemorrhagic (arthropod-borne) NOS
        • Singapore
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • hemorrhagic (arthropod-borne) NOS
        • Southeast Asia
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • hemorrhagic (arthropod-borne) NOS
        • Thailand
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Philippine hemorrhagic
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Singapore hemorrhagic
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Southeast Asia hemorrhagic
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • Thailand hemorrhagic
    • Singapore hemorrhagic fever
    • Southeast Asian hemorrhagic fever
    • Thailand hemorrhagic fever

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF008
Viral infection
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Dengue

    an acute febrile disease transmitted by the bite of aedes mosquitoes infected with dengue virus. it is self-limiting and characterized by fever, myalgia, headache, and rash. severe dengue is a more virulent form of dengue.

  • Dengue Vaccines

    vaccines or candidate vaccines used to prevent infection with dengue virus. these include live-attenuated, subunit, dna, and inactivated vaccines.

  • Dengue Virus

    a species of the genus flavivirus which causes an acute febrile and sometimes hemorrhagic disease in man. dengue is mosquito-borne and four serotypes are known.

  • Severe Dengue

    a virulent form of dengue characterized by thrombocytopenia and an increase in vascular permeability (grades i and ii) and distinguished by a positive pain test (e.g., tourniquet pain test). when accompanied by shock (grades iii and iv), it is called dengue shock syndrome.

  • Flavivirus

    a genus of flaviviridae containing several subgroups and many species. most are arboviruses transmitted by mosquitoes or ticks. the type species is yellow fever virus.

  • Dengue Hemorrhagic Fever

    a serious condition caused by dengue virus infection. patients present with an acute febrile illness followed by restlessness, irritability, and bleeding. it may lead to hemorrhagic shock and death.

Patient EducationClinical

Dengue

Dengue is a viral infection. It can be caused by four related viruses. You can get it if an infected mosquito bites you. It is common in warm, wet areas of the world. Although rare, it can be found in some parts of the United States. Outbreaks are more common during rainy seasons.

The full article covers:

  • What is dengue?
  • How does dengue spread?
  • What are the symptoms of dengue and severe dengue?
  • How is dengue diagnosed?
  • What are the treatments for dengue?
  • Can dengue be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A91 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
065.4 Mosquito-borne hem fever
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A91Overview

Is A91 (Dengue hemorrhagic fever) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report dengue hemorrhagic fever on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A91 group to?

When dengue hemorrhagic fever is the principal diagnosis on an inpatient stay, it groups to MS-DRG 865, 866, with relative weights from 0.8696 to 1.4983 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A91?

Under the General Equivalence Mappings, dengue hemorrhagic fever converts to ICD-9-CM 065.4 (mosquito-borne hem fever). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.