Tick-borne viral encephalitis (A84)

ICD-10 code A84 identifies infections classified as tick-borne viral encephalitis, a group of viral diseases affecting the brain caused by viruses transmitted through tick bites.

This section covers several specific forms of tick-borne viral encephalitis. A84.0 is used for Far Eastern tick-borne encephalitis, also called Russian spring-summer encephalitis, caused by the Far Eastern tick-borne encephalitis virus. A84.1 refers to Central European tick-borne encephalitis, linked to the European subtype of the virus. Codes like A84.8 and A84.89 classify other types, including illnesses from viruses such as louping ill and Siberian tick-borne encephalitis virus. A84.81 specifically defines Powassan virus disease, which can present as invasive or neuroinvasive encephalitis. When the exact virus is not identified, A84.9 is applied as unspecified tick-borne viral encephalitis. Using these codes correctly helps pinpoint the cause of viral encephalitis related to tick exposure for accurate diagnosis and reporting.