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  3. A00–B99
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  5. Mosquito-borne viral encephalitis (A83)

Mosquito-borne viral encephalitis (A83)

The ICD-10 codes in the A83 category classify various types of mosquito-borne viral encephalitis, a serious brain inflammation caused by viruses transmitted by mosquitoes. These codes are used to specifically identify infections such as Japanese encephalitis, Western and Eastern equine encephalitis, and other related viral conditions linked to mosquito vectors.

This section includes detailed codes for well-known mosquito-borne encephalitis diseases. For example, A83.0 covers Japanese encephalitis, also known as Koutango virus or Usutu virus encephalitis. Similarly, A83.1 and A83.2 correspond to Western equine encephalitis and Eastern equine encephalitis, respectively, both caused by Alphavirus infections. A83.3 captures St Louis encephalitis, while A83.4 codes Australian encephalitis, including West Nile virus disease. Other codes like A83.5 represent California encephalitis, with infections related to Jamestown Canyon and La Crosse viruses. The category also covers less common types such as Rocio virus disease (A83.6) and various other mosquito-related viral encephalitis under A83.8. When the specific virus is unknown, A83.9 is used for unspecified mosquito-borne viral encephalitis. These codes help healthcare professionals and coders precisely document and report distinct mosquito-transmitted viral brain infections for accurate diagnosis and treatment tracking.

Instructional Notations

Includes

This note appears immediately under a three character code title to further define, or give examples of, the content of the category.

  • mosquito-borne viral meningoencephalitis

Type 2 Excludes

A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

  • Venezuelan equine encephalitis A92.2
  • West Nile fever A92.3
  • West Nile virus A92.3

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

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.

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.

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.