A84: ICD10 Code for Tick-borne viral encephalitis
A84 is the ICD10 code used for documenting Tick-borne viral encephalitis in clinical and billing records.

A84 represents Tick-borne viral encephalitis, a serious viral infection affecting the brain or spinal cord. These conditions can lead to neurological complications and require prompt diagnosis and treatment. Proper classification using this ICD10 code ensures consistency in medical records, supports surveillance efforts, and guides appropriate care in both inpatient and outpatient settings.
Symptoms
- Fever – Often one of the first symptoms
- Headache – Severe and persistent
- Neck stiffness – Common in meningitis and encephalitis
- Muscle weakness or paralysis – Notable in poliomyelitis
- Seizures – Possible in cases involving brain inflammation
- Confusion or disorientation – Indicative of CNS involvement
- Photophobia – Sensitivity to light, often in viral meningitis
Diagnosis
Diagnosis of Tick-borne viral encephalitis involves clinical assessment, neurological examination, and laboratory tests. Lumbar puncture for cerebrospinal fluid (CSF) analysis is key to diagnosing meningitis or encephalitis. MRI or CT scans may be used to visualize brain inflammation. PCR tests, viral cultures, and serologic studies help identify the causative virus and confirm the diagnosis.
ICD10 Code Usage
ICD10 code A84 is used in hospitals, outpatient settings, and public health databases to track viral infections of the central nervous system. This code supports clinical documentation, insurance billing, and epidemiological monitoring. It helps standardize diagnosis across healthcare systems, ensuring accurate reporting and facilitating coordinated responses to outbreaks.
Related Codes
- A80 – Acute poliomyelitis
- A81 – Atypical virus infections of central nervous system
- A82 – Rabies
- A83 – Mosquito-borne viral encephalitis
- A85 – Other viral encephalitis, not elsewhere classified
- A86 – Unspecified viral encephalitis
- A87 – Viral meningitis
- A88 – Other viral infections of central nervous system, not elsewhere classified
- A89 – Unspecified viral infection of central nervous system
FAQs
Q1: What is ICD10 code A84?
A: It is a standardized diagnostic code used to classify Tick-borne viral encephalitis in health records and billing systems.
Q2: Are these infections contagious?
A: Some are, depending on the virus and mode of transmission (e.g., mosquito bites, saliva, fecal-oral route).
Q3: Can these conditions cause long-term effects?
A: Yes, many can result in neurological deficits or chronic complications if untreated.
Q4: Is hospitalization required?
A: Often yes, especially in severe cases with neurological symptoms or altered consciousness.
Q5: Are vaccines available?
A: Yes, vaccines exist for some (e.g., polio, rabies, Japanese encephalitis) but not all CNS viral infections.
Conclusion
ICD10 code A84 is essential for documenting and managing cases of Tick-borne viral encephalitis. Accurate use ensures quality care, supports public health tracking, and aids in timely interventions during outbreaks. Recognizing and coding these serious infections accurately helps improve patient outcomes and healthcare system efficiency.

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