ICD-10-CM Diagnosis Code A83.8 - Other mosquito-borne viral encephalitis (original) (raw)
ICD List 2025-2026 Edition
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- 2026 ICD-10-CM Code A83.8
Other mosquito-borne viral encephalitis
ICD-10-CM Code:
A83.8
ICD-10 Code for:
Other mosquito-borne viral encephalitis
Is Billable?
Yes - Valid for Submission
Chronic Condition Indicator: [1]
Not chronic
Code Navigator:
A83.8 is a billable diagnosis code used to specify a medical diagnosis of other mosquito-borne viral encephalitis. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2025 through September 30, 2026.
- Code Information
- Approximate Synonyms
- Clinical Classification
- Clinical Information
- Tabular List of Diseases and Injuries
- Index to Diseases and Injuries References
- Convert to ICD-9 Code
- Patient Education
- Other Codes Used Similar Conditions
- Code History
- Certain infectious and parasitic diseases
A00–B99
The following list of clinical terms are approximate synonyms, alternative descriptions, or common phrases that might be used by patients, healthcare providers, or medical coders to describe the same condition. These synonyms and related diagnosis terms are often used when searching for an ICD-10 code, especially when the exact medical terminology is unclear. Whether you're looking for lay terms, similar diagnosis names, or common language alternatives, this list can help guide you to the correct ICD-10 classification.
- Dengue
- Dengue virus encephalitis
- Encephalitis caused by Alphavirus
- Encephalitis caused by Me Tri virus
- Ilheus virus encephalitis
- Kokobera virus encephalitis
- Semliki forest fever
- Stratford virus encephalitis
Clinical Classifications group individual ICD-10-CM diagnosis codes into broader, clinically meaningful categories. These categories help simplify complex data by organizing related conditions under common clinical themes.
They are especially useful for data analysis, reporting, and clinical decision-making. Even when diagnosis codes differ, similar conditions can be grouped together based on their clinical relevance. Each category is assigned a unique CCSR code that represents a specific clinical concept, often tied to a body system or medical specialty.
CCSR Code: NVS002
Inpatient Default: Y - Yes, default inpatient assignment for principal diagnosis or first-listed diagnosis.
Outpatient Default: Y - Yes, default outpatient assignment for principal diagnosis or first-listed diagnosis.
CCSR Code: INF008
Inpatient Default: N - Not default inpatient assignment for principal diagnosis or first-listed diagnosis.
Outpatient Default: N - Not default outpatient assignment for principal diagnosis or first-listed diagnosis.
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.
The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).
- - Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) - G04.90
- - Ilheus (virus) - A83.8
- - viral, virus - A86
* - arthropod-borne NEC - A85.2
* - mosquito-borne - A83.9
* - specified NEC - A83.8
References found for this diagnosis code in the External Cause of Injuries Index:
- Encephalitis(chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)
- Ilheus (virus)
- Encephalitis(chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute)
- viral, virus
- arthropod-borne NEC
- mosquito-borne
- specified NEC
- mosquito-borne
- arthropod-borne NEC
- viral, virus
Below are the ICD-9 codes that most closely match this ICD-10 code, based on the General Equivalence Mappings (GEMs). This ICD-10 to ICD-9 crosswalk tool is helpful for coders who need to reference legacy diagnosis codes for audits, historical claims, or approximate code comparisons.
ICD-9-CM: 062.8
Approximate Flag - The approximate mapping means this ICD-10 code does not have an exact ICD-9 equivalent. The matched code is the closest available option, but it may not fully capture the original diagnosis or clinical intent.
Encephalitis
What is encephalitis?
Encephalitis is inflammation (swelling) of the brain. It can happen when an infection or medical condition that affects the brain activates your immune system. The inflammation can cause a wide range of symptoms. In extreme cases, it can lead to brain damage, stroke, or even death.
What causes encephalitis?
There are different types of encephalitis, based on what the cause is. The two main types are infectious encephalitis and autoimmune encephalitis.
Infectious encephalitis is usually caused by a virus. In fact, viruses are the most common cause of encephalitis. Some of the different viruses that cause it include:
- Herpes viruses, including herpes simplex (HSV), the Epstein-Barr virus (which causes infectious mononucleosis) and the varicella-zoster virus (which causes chickenpox).
- Viruses you can get if you are bitten by an infected tick, such as tick-borne encephalitis (TBE virus) and Powassan virus.
- Viruses you can get if you are bitten by an infected mosquito, such as eastern equine encephalitis virus, West Nile virus, and La Crosse virus.
- Enteroviruses, which are a common group of viruses that mostly cause mild illness or respiratory infection. These infections usually happen in the summer and fall.
Bacteria, fungi, and parasites can also cause infectious encephalitis. But this is not common.
Autoimmune encephalitis happens when your immune system mistakenly attacks healthy brain cells. It can be triggered by conditions such as certain cancers, benign tumors, and infections. Sometimes the cause is not known.
Who is more likely to get encephalitis?
Anyone can get encephalitis, but you are more likely to get it if you:
- Have a weakened immune system, for example from having HIV or taking certain medicines. These could include medicines taken after an organ transplant, certain chemotherapy medicines, and specialized treatments for certain autoimmune diseases.
- Are a young child or older adult.
- Live in areas where there are ticks and mosquitoes that carry viruses that can cause encephalitis.
What are the symptoms of encephalitis?
The symptoms of encephalitis can vary a lot, depending on how severe it is. Many people do not have any symptoms. Others may have mild flu-like symptoms such as fever, fatigue, headache, or body aches. If encephalitis becomes more serious, it can cause:
- Severe headache
- Stiff neck
- Vomiting
- Seizures
- Behavior changes
- Drowsiness
- Muscle weakness
- Partial paralysis in your arms and legs
- Coma
Encephalitis can be dangerous in infants. Their symptoms may include:
- Fever
- Lethargy (weakness or drowsiness)
- Poor feeding
- Vomiting
- Body stiffness
- Unusual irritability or crying
- A full or bulging fontanel (the soft spot on the top of the head)
If you or your child is having symptoms of encephalitis, it's important to get medical care right away.
How is encephalitis diagnosed?
To find out if you have encephalitis, your health care provider:
- Will do a physical exam
- Will take your medical history, which includes asking about your symptoms
- May do a neurologic exam
- May order imaging tests, such as a brain CT scan or MRI
- May order an EEG (electroencephalography), which use small electric sensors to measure your brain activity
- May order blood and cerebrospinal fluid (CSF) tests
What are the treatments for encephalitis?
Most people with encephalitis will need treatment in the hospital. Depending on the cause, treatments may include antiviral medicines, antibiotics, corticosteroids, and other medicines.
For some types of encephalitis, there is no medicine to treat it. But rest, nutrition, and fluids can help your body fight the infection and relieve symptoms.
Some people may need physical, speech, and occupational therapy once the illness is under control.
Can encephalitis be prevented?
There are steps you can take to help prevent encephalitis that is caused by infections:
- Use good hygiene, including washing your hands often with soap and water.
- Don't share food, drinks, utensils, and glasses with other people.
- Get vaccines for viruses that can cause encephalitis.
- Avoid mosquito and tick bites, for example by:
- Wearing insect repellent with DEET or another U.S. Environmental Protection Agency (EPA)-registered insect repellent. Make sure to follow the instructions for using the repellant.
- Wearing clothes that cover your arms, legs and feet.
- Treating your clothing and gear with products containing 0.5% permethrin before you go in grassy or woody areas.
NIH: National Institute of Neurological Disorders and Stroke
Viral Infections
What are viruses?
Viruses are very tiny germs. They are made of genetic material (either DNA or RNA) inside of a protein coating. There are a huge number of viruses on earth. Only a small number of them can infect humans. Those viruses can infect our cells, which may cause disease. Some of the diseases that viruses can cause include the common cold, the flu, COVID-19, and HIV.
How are viruses spread?
Viruses can be spread in different ways:
- Through droplets and particles that are breathed out by someone who has the infection. You might breathe in the droplets or particles, or they could land on your mouth, nose, or eyes.
- By touching surfaces or objects that have the virus on them and then touching your mouth, nose, or eyes.
- From the pregnant parent to the baby during pregnancy.
- Through contaminated food or water.
- By being bitten by an infected insect or animal.
- Through sexual contact (usually vaginal, anal and oral sex) with someone who has the infection.
How do viruses cause disease?
Viruses are like hijackers. They invade living, normal cells. They then use those cells to multiply (make copies of themselves). This process is also called replication. The process can kill, damage, or change the infected cells. Sometimes this can make you sick. The symptoms can range from mild to very severe. Other times, your immune system may be able to fight it off and you may not have any symptoms.
Each different virus usually only infects one type of cell in your body. For example, hepatitis viruses affect the cells in the liver. HIV infects a certain type of immune system cell.
What are the treatments for viral infections?
For most viral infections, treatments can only help with symptoms while you wait for your immune system to fight off the virus. There are antiviral medicines to treat some viral infections. Antibiotics do not work for viral infections.
Can viral infections be prevented?
Vaccines can help prevent you from getting many viral diseases. You may be able to prevent some viral infections by:
- Proper hand washing.
- Paying attention to food safety.
- Cleaning surfaces that may be infected with germs.
- Avoiding contact with wild animals.
- Preventing insect bites by using insect repellent when you go outdoors. If you travel to an area that has a high risk of diseases from insect bites, also wear long pants, shirts, and socks.
- Practicing safe sex (using a condom every time you have anal, vaginal, or oral sex).
- Avoiding close contact with people who are sick.
FY 2026 - No Change, effective from 10/1/2025 through 9/30/2026
FY 2025 - No Change, effective from 10/1/2024 through 9/30/2025
FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.
