ICD-10 Code B33.1 – Ross River disease (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B33.1 – Ross River disease
What it is
B33.1 identifies Ross River disease, a mosquito-borne viral illness that can cause systemic infection. Use it for documented Ross River virus infection when the diagnosis is confirmed or clearly stated in the record.
Clinical signs
Typical features include fever, rash, and joint pain, often with fatigue and muscle aches. Clinical features vary; refer to documentation, especially when the presentation is nonspecific or overlap with other arboviral illnesses is possible.
When to use this code
Use B33.1 when the provider documents Ross River disease, Ross River virus infection, or a confirmed clinical diagnosis. It may also fit encounters for ongoing symptoms after the acute illness if the diagnosis remains Ross River disease. Check documentation if the chart only notes exposure, suspected infection, or travel history.
Do not use for
Do not use this code for undiagnosed fever, generic viral illness, or arthralgia without a documented Ross River diagnosis. Do not assign it for other mosquito-borne infections unless the record specifically identifies Ross River disease.
Coding tip
Code the documented diagnosis, not the vector exposure alone; if the organism is not named, check documentation.