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ICD-10 Guide
ICD-10 CodesB05.2

B05.2

Measles virus encephalitis

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/05/2025

Code Description

ICD-10 B05.2 is a billable code used to indicate a diagnosis of measles virus encephalitis.

Key Diagnostic Point:

Measles virus encephalitis is a rare but serious complication of measles infection, typically occurring 7 to 10 days after the onset of the measles rash. It is characterized by inflammation of the brain, which can lead to neurological deficits, seizures, and even death. The pathophysiology involves the direct invasion of the central nervous system by the measles virus, leading to an immune-mediated response that causes neuronal damage. Symptoms may include fever, headache, confusion, and altered consciousness, progressing to more severe manifestations such as ataxia and coma. Diagnosis is primarily clinical, supported by serological tests for measles virus antibodies and, in some cases, PCR testing of cerebrospinal fluid. Early recognition and management are crucial, as the condition can lead to long-term neurological sequelae. Vaccination against measles is highly effective and is the primary preventive measure against this serious complication.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Requires understanding of viral encephalitis and its complications
  • Differentiation from other types of encephalitis
  • Need for accurate documentation of clinical symptoms and laboratory findings
  • Potential for misclassification with other viral infections

Audit Risk Factors

  • Inadequate documentation of vaccination history
  • Failure to document neurological symptoms clearly
  • Misdiagnosis or coding of encephalitis due to other viruses
  • Lack of supporting laboratory results

Specialty Focus

Medical Specialties

Pediatrics

Documentation Requirements

Detailed history of vaccination status, clinical symptoms, and neurological examination findings.

Common Clinical Scenarios

Children presenting with fever, rash, and neurological symptoms following measles infection.

Billing Considerations

Consideration of the child's vaccination history and potential for complications from measles.

Neurology

Documentation Requirements

Comprehensive neurological assessment and imaging studies to evaluate encephalitis.

Common Clinical Scenarios

Patients with altered mental status and seizures following measles infection.

Billing Considerations

Need for detailed documentation of neurological deficits and response to treatment.

Coding Guidelines

Inclusion Criteria

Use B05.2 When
  • According to ICD
  • 10 guidelines, B05
  • 2 should be used when the encephalitis is specifically due to the measles virus
  • It is important to document the clinical presentation and any laboratory findings that support the diagnosis

Exclusion Criteria

Do NOT use B05.2 When
  • Exclusion criteria include encephalitis caused by other viral agents

Related CPT Codes

87491CPT Code

Measles virus detection by PCR

Clinical Scenario

Used when confirming measles virus as the cause of encephalitis.

Documentation Requirements

Documentation of clinical symptoms and rationale for testing.

Specialty Considerations

Pediatric infectious disease specialists may frequently order this test.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of conditions like measles virus encephalitis, improving the accuracy of data collection and reimbursement processes.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of conditions like measles virus encephalitis, improving the accuracy of data collection and reimbursement processes.

Reimbursement & Billing Impact

reimbursement processes.

Resources

Clinical References

  • •
    CDC Measles Information

Coding & Billing References

  • •
    CDC Measles Information

Frequently Asked Questions

What are the symptoms of measles virus encephalitis?

Symptoms may include fever, headache, confusion, seizures, and altered consciousness, often occurring 7 to 10 days after the measles rash appears.

How is measles virus encephalitis diagnosed?

Diagnosis is primarily clinical, supported by serological tests for measles antibodies and PCR testing of cerebrospinal fluid.

What is the importance of vaccination in preventing measles virus encephalitis?

Vaccination against measles is highly effective and is the primary preventive measure against measles and its complications, including encephalitis.